# Idle - Lumpy / Intermittent Misfire - It's Fixed! PG7



## EnthusiastOwned (Mar 14, 2014)

Hello,

2005 TT QS - Covered 45k

I've noticed a lumpy idle where the rev counter fluctuates ever so slightly. VAGCOM shows no errors and the idle sites between 720-760 fluctuating.

On cold start the revs are just over 1k where they settle to the above fluctuating revs after a minute or so.

I have also noticed an intermittent misfire on idle - When warmed up. It happens randomly and every once in a while - Sometimes the odd misfire, maybe once in 5 mins of idling but then sometimes two or three times in 30 seconds then is stops for a few minutes. It's like the car wants to cut out and the engine shudders all for a split second- Although the rev counter doesn't drop. I haven't felt any misfires when driving but it does feel a little hesitant every once in a while (intermittent) - like it's holding back. The car pulls hard on boost but it feels intermittent, sometimes it pulls harder - But I'm not sure if this is in my head or not.

The misfire is more apparent when the car is really warmed up and up to temp - After a long drive or a spirited one.

Vagcom says a misfire on cylinder 3 when looking at the blocks (but in all fairness that was a brief check when idling).

I've changed the PCV valve and suction valve (I didn't change the pancake cam breather valve though). I've had the inlet off and checked for boost leaks and replaced most of the breather pipework with forge items and genuine vag. I've done a smoke test with no leaks in the system indicated.

The plugs have been replaced with NGK BKR7E's which made no difference.

I've done the 49c and 51c trick. 51c gets to 90 and stays there. 49c gets to 90 fairly quick then fluctuates between 87 and 98 depending on driving conditions.

The coilpacks are all genuine and not covered under the recall. The coilpack wiring seems ok, hard but in one piece - although the earth on the cam cover has split insulation. The TB has been cleaned and re-set.

Whats next to check or replace?


----------



## TheVarix (Apr 3, 2013)

Have you checked your MAF sensor? Have you tried to unplug it to see if it makes any difference?
I think the MAF could be the cause of your problems when idling and a decrease in performance. 
About the misfires it's harder to tell, in my opinion it could be another symptom of the MAF failing or the coil packs (since you've replaced the spark plugs recently)


----------



## EnthusiastOwned (Mar 14, 2014)

TheVarix said:


> Have you checked your MAF sensor? Have you tried to unplug it to see if it makes any difference?
> I think the MAF could be the cause of your problems when idling and a decrease in performance.
> About the misfires it's harder to tell, in my opinion it could be another symptom of the MAF failing or the coil packs (since you've replaced the spark plugs recently)


I've not looked at the MAf to be honest.

Whats the best way to test it? Unplug it and take it for a drive to see if it makes a difference?


----------



## TheVarix (Apr 3, 2013)

EnthusiastOwned said:


> I've not looked at the MAf to be honest.
> Whats the best way to test it? Unplug it and take it for a drive to see if it makes a difference?


You can if you want, but I'd recommend that only for a short ride to test. Unplugging is a "quick/shortcut" method to find out.
If the ECU can't read any signal from the MAF it will use a default (and I think richer) air/fuel ratio so once you disconnect the MAF, if there's little or no difference (or even an improvement) your MAF is faulty but if it's worse than with it plugged, then you know it's not the MAF.
Another options would be to check the voltage or the MAF readings using VCDS.


----------



## EnthusiastOwned (Mar 14, 2014)

TheVarix said:


> EnthusiastOwned said:
> 
> 
> > I've not looked at the MAf to be honest.
> ...


Ahh right. I'll give it a go tonight. Will it make a difference on idle or does it need to be driven?

How do I test the readings on VAGCOM?


----------



## TheVarix (Apr 3, 2013)

Yes, in theory you should feel (or not) the difference already when idling.
Regarding the measuring blocks and parameters you need to check in vcds, I don't know as I am not too familiar with it. Member skeee and others are so hopefully you'll get some advice soon.


----------



## EnthusiastOwned (Mar 14, 2014)

Well,

Update to this.

After my dive home from work (so the car was fully warmed up) I unplugged the MAF whilst idling. There was a split second hiccup then the car idled as it did before, The ESP light came on the dash though. I went for a quick drive and there was no apparent change to the way it drives. It could have been a bit more eager but then again it could have been in my head.

Although when I came back home I let it idle some more, it was still lumpy but I couldn't really feel the misfire - Although it wasn't idling that long. Plugged the MAF back in and the car hiccuped again. The idle settled for a split second then the ESP went out and the idle fluctuated again as normal, the misfires returned withing about 10 seconds.

There wasn't much difference to the way the engine performed, MAF plugging in or not. It could have been a small fraction better with it unplugged, but like I say it could be in my head.

Thoughts?


----------



## Skeee (Jun 9, 2009)

http://www.ross-tech.com/vag-com/m_blocks/
http://www.ross-tech.com/vag-com/m_blocks/010-019.html

<01-Engine >
Blocks 14 & 15 & 16.

Also as you discovered, the MAF sends a signal to the ABS for the ESP so when the MAF is disconnected the ESP will fail, and put the light on.


----------



## EnthusiastOwned (Mar 14, 2014)

Thanks for that. The first link is really useful. 8)

I know the cars misfiring though. Cylinder 3 as far as I can tell. Would it be best to log the misfires so I know whats what?

Does the MAF look dodgy though? I was under the impression that is the MAF was good there would be a dramatic change if it's unplugged?


----------



## TheVarix (Apr 3, 2013)

Hi, 
In my opinion the MAF is faulty but it's better to double check it with VCDS just in case so you don't end up buying a part you don't need...


----------



## EnthusiastOwned (Mar 14, 2014)

I've had another look at the car.

MAF plugged in or not and the car misfires on idle, on all cylinders not just cylinder 3 as previously thought. Still intermittent. I get around 2-4 misfires in a 5 minute window. The car actually feels as if it's misfiring more but they aren't severe enough to be picked up by VAGCOM, only the big stutters are registering.

As far as I can see unplugging the MAF not makes very little difference to the severity, if at all.

I've taken the MAF off and given it a clean with MAF cleaner. No difference.

The MAF part number is: 06A 906 461 M and it's dated 02/05 so I presume original.

Any other opinions that it's a faulty MAF before I fork out for a new one?


----------



## TheVarix (Apr 3, 2013)

To be honest it sounds consistent with a faulty MAF. If in the end you decide to buy a new one, where are you going to get it from? 
ECP for example sells APX MAfs for 225s for around £66 and they're Bosch units.


----------



## EnthusiastOwned (Mar 14, 2014)

I'm not sure yet. I need to shop around.

I want the proper part for a BAM/BFV engine code. Bosch or Genuine. I might try TPS as I get trade.

Any other second opinions please before I she'll out for one?


----------



## fixitagaintomoz (Apr 26, 2013)

Just throwing ideas up in the air to be considered

Coil packs
Fuel pressure


----------



## Matt B (Apr 8, 2007)

it could be the wiring to the coilpacks - have you had a good look at the loom?


----------



## EnthusiastOwned (Mar 14, 2014)

fixitagaintomoz said:


> Just throwing ideas up in the air to be considered
> 
> Coil packs
> Fuel pressure


Is it normal for all 4 coilpacks to start breaking down together?

Could be fuel pressure? Can it be tested in anyway?



Matt B said:


> it could be the wiring to the coilpacks - have you had a good look at the loom?


Could be I suppose. I took a quick look recently but I think a proper look is in order.


----------



## TheVarix (Apr 3, 2013)

If one of your coilpacks is going, the others will probably be not too far from the end of their lives.


----------



## EnthusiastOwned (Mar 14, 2014)

TheVarix said:


> If one of your coilpacks is going, the others will probably be not too far from the end of their lives.


Gutted! I thought they would have lasted more than 45k!

So, to sum up so far, it could be my MAF, could be my coilpacks, could be my wiring.

I'm reluctant to start swapping stuff for the sake if it. Surely there is a more defining way to test for failed parts?


----------



## TheVarix (Apr 3, 2013)

I don't think it's going to be the coilpacks. Not with 45k miles if they are OEM.
You're saying that the misfires barely register in the log and as I said, it looks more than probable that it's going to be the MAF but obviously I can't assure you 100%. 
When my coilpacks went my symptoms were jerkiness/shuddering on hard acceleration/boost. 
In my previous car I had misfires when after using a garage serviced the car they fitted the wrong type of spark plugs. If you're not sure, take it to a VAG specialist mechanic to have it checked.


----------



## EnthusiastOwned (Mar 14, 2014)

TheVarix said:


> I don't think it's going to be the coilpacks. Not with 45k miles if they are OEM.
> You're saying that the misfires barely register in the log and as I said, it looks more than probable that it's going to be the MAF but obviously I can't assure you 100%.
> When my coilpacks went my symptoms were jerkiness/shuddering on hard acceleration/boost.
> In my previous car I had misfires when after using a garage serviced the car they fitted the wrong type of spark plugs. If you're not sure, take it to a VAG specialist mechanic to have it checked.


I was going to say the if the coilpacks were on there way out it'd show under load rather than idle. When driving no misfires register at all.

I'm going to rive home tonight with the MAF unplugged and see it it feels any better on a longer drive.


----------



## fixitagaintomoz (Apr 26, 2013)

Maf unplugged means it runs off stock settings, and runs a bit lean. so will be better but still not ideal. worth also checking that the maf is the correct variant for your model- there are a few about!


----------



## EnthusiastOwned (Mar 14, 2014)

fixitagaintomoz said:


> Maf unplugged means it runs off stock settings, and runs a bit lean. so will be better but still not ideal. worth also checking that the maf is the correct variant for your model- there are a few about!


Thats what I thought. The MAF is the correct variant - Unless someone has changed the sensor in the housing without telling me.

So if there is a fault (which isn't the MAF) causing it to already be running on stock settings, unplugging the MAF won't do anything as it's already on stock mode? Or would it make an additional difference?


----------



## Hoggy (May 8, 2002)

Hi, Unplugging the MAF will cause it to run rich (fail safe), 
If MAF is O.K. & the prob is caused by weak mixture due to an air leak, disconnecting MAF could hide the air leak prob.
Hoggy.


----------



## FRAX (Jul 21, 2013)

May be a daft one but costs nothing to check. Remove the earth from the coil pack (at rocker cover)and give it a good clean with some emery paper and also clean the same bit on the rocker cover, if the earth is bad the coil pack will play up on idle buy may be more masked at speed.
Just a thought.


----------



## EnthusiastOwned (Mar 14, 2014)

Hoggy said:


> Hi, Unplugging the MAF will cause it to run rich (fail safe),
> If MAF is O.K. & the prob is caused by weak mixture due to an air leak, disconnecting MAF could hide the air leak prob.
> Hoggy.


Well, the more I think about it the more I don't think the MAF is at fault. There isn't enough of a drastic change to indicate it's the MAF when it's unplugged. Which to me indicates the issue is elsewhere in the system and the car is already in fail-safe mode.



FRAX said:


> May be a daft one but costs nothing to check. Remove the earth from the coil pack (at rocker cover)and give it a good clean with some emery paper and also clean the same bit on the rocker cover, if the earth is bad the coil pack will play up on idle buy may be more masked at speed.
> Just a thought.


It's one of my plans this weekend. I'm going to strip the loom back and check the wiring.

I'm also going to clean the N75 and N249 to see if there is a difference whilst checking boost pipes. Can't hurt.

I'm swapping out the plugs too for the older ones just in case (only done 5k and they are the platinum NGK)


----------



## EnthusiastOwned (Mar 14, 2014)

Update to this.

I've pulled all the coilpack wiring apart. Other than some cracked insulation, the wires themselves are fine all with good continuity. I taped them all up with new insulation tape and also cleaned the earth which sits on the rocker cover. I also changed the spark plugs for some NGK PFR6Q's as a matter of precaution. The coilpacks were swapped around to see if it effects anything. On that note they are all genuine with the part number 06A 905 115 D.

I also double checked the boost hoses near the turbo, the tip, DV etc. All are good.

I cleaned the MAF again and also the N75 and N249.

The car doesn't seem to misfire any more and the idle has improved.

BUT... It's still under performing with the hesitant boost. The boost builds and kicks in around 3k but it seems really flat and doesn't pull as hard as it should. I can also hear the car breathing at all revs, like it's dumping boost, it's more apparent when tootling around on light throttle. The car doesn't have any boost leaks which has been confirmed by a smoke test. Could the actuator be stuck open?


----------



## FRAX (Jul 21, 2013)

Check the recirculation valve / dump valve, remove it and see if the spring and plunger are free


----------



## EnthusiastOwned (Mar 14, 2014)

FRAX said:


> Check the recirculation valve / dump valve, remove it and see if the spring and plunger are free


I've just fitted a rebuild kit so it's good as new. I've also got a spare genuine valve and it performs the sane with that.


----------



## FRAX (Jul 21, 2013)

Well you know what I have went through with my one, I hope to test it tomorrow and if it fails again I thonk my next move will be to get someone with a rolling road and see if they can check it at high rpm's.
Hold off with yours till I test my one and let you know if the N75 made any improvments.


----------



## fixitagaintomoz (Apr 26, 2013)

Have you got the capability to run logs on vcds? If so you can log requested vs actual boost, and maf readings to give an indication of where the problem is occuring

Also wprth noting that the gaskets on the turbo from the exhaust mani and to the downpipe can go- leading to the noise you describe


----------



## neil_audiTT (Sep 1, 2010)

I think theres more than one fault on that.

So the misfire is sorted now?

50k isnt much for a set of coilpacks. But i wouldn't rule it out - They're properly crap! My first TT on the sign of them failing it would boost but not much, jerks in power delivery then eventually full on misfires.

Isn't the maf. Barking up the wrong tree with that one i feel.

N75 valve, you can check operation of that on VDCS i'm sure. I've seen them start to fail and just create judders in acceleration, or fail full open - car goes like fuck then into limp mode because the ECU recognises a over boost.

When we're the spark plugs changed? They can break down more when the engines warm.


----------



## EnthusiastOwned (Mar 14, 2014)

FRAX said:


> Well you know what I have went through with my one, I hope to test it tomorrow and if it fails again I thonk my next move will be to get someone with a rolling road and see if they can check it at high rpm's.
> Hold off with yours till I test my one and let you know if the N75 made any improvments.


Thanks mate, keep me posted!



fixitagaintomoz said:


> Have you got the capability to run logs on vcds? If so you can log requested vs actual boost, and maf readings to give an indication of where the problem is occuring
> 
> Also wprth noting that the gaskets on the turbo from the exhaust mani and to the downpipe can go- leading to the noise you describe


I do. I'll give it a good run and do some more logs. I'll check the gaskets, although I've not had a good look under the car yet.



neil_audiTT said:


> I think theres more than one fault on that.
> 
> So the misfire is sorted now?
> 
> ...


Yeah, misfires are sorted. The plugs were changed at 40k for the NGK Platinum ones according to the history and I fitted some copper ones at 45k as a matter of me being anal and like to give all my cars a service. I gapped them myself and I had another look last night and I might have bent the electrode pin when gapping which might have been my issue. Either way, after yesterdays play the misfires seem to have gone.

There aren't any jerks when driving it, soft or hard - But the power delivery pulses. Hesitant almost, like it's trying to go but is holding back like he power delivery is in waves.

Like I say, at 3k the boost comes in hard, but it almost peaks at 3k then the power drops instantly, it just feels down on power.


----------



## neil_audiTT (Sep 1, 2010)

N75 

Lad at work had a mapped polo Gti, on the rollers it had small judders in the power curve. Only just feel them on the road.

Swapped that out and she boost perfectly now.

If your diverter valve is fresh and theres no boost leaks, thats really the only thing it can be.


----------



## FRAX (Jul 21, 2013)

Have a llok at viewtopic.php?f=2&t=759385&p=4858329#p4858329 I have just updated.


----------



## EnthusiastOwned (Mar 14, 2014)

Looks like I'll try the N75 then!

Mine is the F Part number so I'll order an upgrade tomorrow. Might try TPS with my trade discount and see what they cost.


----------



## FRAX (Jul 21, 2013)

They are only about £40 from Audi but you may get a better deal.
Keep this updated as to how you get on, they must fail quite often as this is at least the second one my car has had and it just done 45k.
One fitted by me and one by the last owner.
Hope this will also fix it for you.


----------



## EnthusiastOwned (Mar 14, 2014)

FRAX said:


> They are only about £40 from Audi but you may get a better deal.
> Keep this updated as to how you get on, they must fail quite often as this is at least the second one my car has had and it just done 45k.
> One fitted by me and one by the last owner.


Ouch! 2 in that little time?

Hopefully this will sort mine


----------



## fixitagaintomoz (Apr 26, 2013)

I think it is due to the oil vapour that goes through the n75. If the oil is a bit sludgy it can build up and hinder effective operation. Another reason to run a catch tank in my opinion!


----------



## EnthusiastOwned (Mar 14, 2014)

Bit of an update.

Tried a different dump valve just in case. No difference. Got a N75 on order and i'm going to fit it on the weekend.

Logs for now:
View attachment TT Log 18th Sept 2014.xlsx


Thoughts?


----------



## FRAX (Jul 21, 2013)

Glade you got the N75 and I hope it will sort your problem, only takes 5 - 10 min to fit.
Make sure you get it the correct way round though.


----------



## EnthusiastOwned (Mar 14, 2014)

FRAX said:


> Glade you got the N75 and I hope it will sort your problem, only takes 5 - 10 min to fit.
> *Make sure you get it the correct way round though. *


For the avoidance of doubt.. What's the correct way?


----------



## fixitagaintomoz (Apr 26, 2013)

EnthusiastOwned said:


> FRAX said:
> 
> 
> > Glade you got the N75 and I hope it will sort your problem, only takes 5 - 10 min to fit.
> ...


"Re-fitting is the reverse of removal"


----------



## FRAX (Jul 21, 2013)

Well thats right - long end goes to turbo air intake as far as I remember - sure you will get it right.
Is your one still the origonal one and held on by Audi clips ?


----------



## EnthusiastOwned (Mar 14, 2014)

FRAX said:


> Well thats right - long end goes to turbo air intake as far as I remember - sure you will get it right.
> Is your one still the origonal one and held on by Audi clips ?


Nope, it's been removed before. Long end is in the TIP though.

The electrical connector is facing the engine.


----------



## FRAX (Jul 21, 2013)

Well in that case 5 min, at least you dont have the pain of removing the Audi clips.
I hope you can tell the difference before you even leave your drive.


----------



## FRAX (Jul 21, 2013)

Did you get your N75 fitted and if so how did it go.


----------



## EnthusiastOwned (Mar 14, 2014)

I fitted it.

Seems a bit better, although the car still pulses when going through the revs. So I don;t think it was the N75. Yay!


----------



## FRAX (Jul 21, 2013)

Flip I though that would fix it for you, back to racking the brain again then sadly.
I have a spare MAF and N249 if ye need them.
I was sure you would see a differance.


----------



## neil_audiTT (Sep 1, 2010)

I'm officially lost now :lol:

So boost leak, no. 
N75, no
maf, inclined to say no. 
coilpacks, unlikely
coilpack wiring, adjusted

Whats left, Throttle body?
Compression test maybe, Ive seen lumpy idles be the start of HG failures between cylinders. 
Or fuelling - injector or something.

Thinking out loud.


----------



## EnthusiastOwned (Mar 14, 2014)

To be fair, since cleaning all the valves, sorting the coilpack wiring, changing the spark plugs and changing the N75 the car has significantly improved. I'm wondering if it is just me being anal? When taking it through the rev range it's not a 100% smooth pull, it pulses like the power peaks, pulls back a tiny tiny bit then peaks, pulls back a tiny tiny bit etc etc. I'm talking small amounts here that 95% of people wouldn't even realise.

It's pushing 255bhp according to the vagcom MAF readings trick. And the car does seem to go pretty well.

TB has been off, cleaned and re-set. Although I did re-use the gasket. Could be leaking there?

Also when I got the car the injector seats were clearly leaking as there was residue around the seats. I cleaned it up and put on some injector o-rings I had lying around. No more residue at all, but it could be likely that these are leaking too?

I also, at the time of changing my pipework I replaced the two vac pipes from under the inlet manifold to the N249/FPR and also from the N75 to actuator with silicone hoses - I'm wondering if these aren't up to the job and collapsing under the pressure? Or that the actuator is sticking?

Could the timing be out slightly?

I might give it another boost leak test as I have been playing with the pipework a lot.

Oh, I also tried x2 different diverter valves, Genuine N ones, more or less brand new.


----------



## FRAX (Jul 21, 2013)

I was out today with the wife and as usual she went shopping, as I can not stand the thought of that I stayed in the car.
Now the car was sitting on idle at about 8k rpm's and I did see the needle move very slightly up and down and I mean next to nothng.
Turned the radio of so I could listen to the engine and I could hear the engine noise fluctuate - again not a lot but it does do it.


----------



## L33JSA (Jun 30, 2010)

FRAX said:


> .....on idle at about 8k rpm's..


Really?? You wanna get that looked at!! :lol:


----------



## FRAX (Jul 21, 2013)

By god you are right I would need to get that looked at before it blows up   
Should have read 800rpm's


----------



## EnthusiastOwned (Mar 14, 2014)

Same as mine then Frax.

I wonder if it's normal then?


----------



## FRAX (Jul 21, 2013)

I am sure my old 225 did the same, it had done 60k but ran fine.
I do sometimes see the new owner - if I do bump into him I will hae a look.
They might all be like that, sadly I dont know anyone local to go and have a look at.
Could always go for a test drive at a garage though if there is one near by.


----------



## fixitagaintomoz (Apr 26, 2013)

They can fluctuate very slightly, but i dont think it should be noticable audibly


----------



## FRAX (Jul 21, 2013)

I would say my one is more audible than visible but then again I need glasses.


----------



## EnthusiastOwned (Mar 14, 2014)

Just adding to this,

When colder and warming up the car is as smooth as silk. The issue is only apparent when fully up to temp, thats when the idle slightly fluctuates and the power delivery isn't as smooth.

Does this narrow it down? Lambda maybe?


----------



## EnthusiastOwned (Mar 14, 2014)

Another little update.

I've vagcom'd the car again and it came up with 'brake light switch implausable'

I've done a bit of a search and I've read that if the switch is faulty it pulls the throttle back? Hmmmmm. Food for thought.


----------



## neil_audiTT (Sep 1, 2010)

That's interesting.

On another note, your temperature related problem would point towards a coolant temp sensor.

They're bloody crap!

I replaced one on both my previous TT's, and even my mk2 with 12000 miles on the clock ha!

That did cause some odd running...

Brake light switch - replaced one of those too on my last TT. That just put the ABS light on. Cheap fix and a doddle to change.


----------



## EnthusiastOwned (Mar 14, 2014)

neil_audiTT said:


> That's interesting.
> 
> On another note, your temperature related problem would point towards a coolant temp sensor.
> 
> ...


I've done the 49c trick and everything seems normal though? Could the temp sensor still be faulty? What symptoms should I be seeing if it's faulty?

Brake sensor is a strange one though as it's coming up under haldex? I think?


----------



## neil_audiTT (Sep 1, 2010)

Yeah but theres two halfs to it. So 49c can work fine, (which is the same as the temp gauge on the dash) The other sends the signal to the ECU. (4 pins in the plug)

Sometimes the symptoms can be quite adverse. But normally show themselves when the engine is up to operating temp. My V6 used to hold back abit, but not all the time. I'd find myself leaning forward like you do when you downshift without realising the power of engine brake but with my foot planted :lol:

Come to think of it, similar symptoms to yours. Bit of a lumpy idle and used more fuel.

That's not the one you get every time is it? When parked you normally get a haldex flag because the cars stationary and the haldex isnt energised.


----------



## EnthusiastOwned (Mar 14, 2014)

neil_audiTT said:


> Yeah but theres two halfs to it. So 49c can work fine, (which is the same as the temp gauge on the dash) The other sends the signal to the ECU. (4 pins in the plug)
> 
> Sometimes the symptoms can be quite adverse. But normally show themselves when the engine is up to operating temp. My V6 used to hold back abit, but not all the time. I'd find myself leaning forward like you do when you downshift without realising the power of engine brake but with my foot planted :lol:
> 
> ...


Hmm, mine is the original black temp sensor. Might be worth a change then!

I'm not sure? Is it normal to pop up then?


----------



## neil_audiTT (Sep 1, 2010)

Hopefully that'll be it!

It's clearly had more than one fault though. So should be running like a dream soon!

Are you using VCDS or vagcom?

Stored faults is where the brake pedal one will be if its a genuine fault, clear it and see if it comes back.

I dont remember the exact wording, but i'm sure the word haldex is in there and showing as a fault if you're stationary and scanning, It's a while since ive played with it but it rings a bell :lol:


----------



## EnthusiastOwned (Mar 14, 2014)

neil_audiTT said:


> Hopefully that'll be it!
> 
> It's clearly had more than one fault though. So should be running like a dream soon!
> 
> ...


Looks that way. Bloody cars!

I use Vagcom. The brake sensor is under the haldex controller and stored. It's actually popped up a few times before but I thought nothing of it because my brake lights work and just thought it was playing sillybuggers.

Apparently it's a two stage switch and controls the ABS/ECU so if it's faulty the ECU dials back throttle as a fail safe.. Hmmmm.

I'll try a new brake sensor and green temp sensor. Nothing to lose.


----------



## EnthusiastOwned (Mar 14, 2014)

Bit of an update.

Fitted a genuine green temp sensor. The one I removed was black and original! The dash and 49c behaves exactly the same.

I also fitted a new brake light switch. The one removed looks to be non OE and fairly recent. Fault code has disappeared though!

The car feels a bit more livelier but in all honesty that's probably in my head and there is no real noticeable deference. Great. 

All vagcom cleared, no fault codes etc etc.

The idle is still slightly rough and I noticed the odd hiccup every once in a while, cylinder two counted 1 misife in about 10 minutes. I went though all of the measuring blocks to see if anything jumped out at me.

Group 026 - Knock Sensor Voltage

0.585v 0.936v 0.585v 0.585v

Coincidence?


----------



## EnthusiastOwned (Mar 14, 2014)

Another update.

I managed to get a brand new genuine n249 valve relatively cheap so I'm going to try that at the weekend.

I've also been told to check my lambda. Apparently if the lambda is duff or failing it will effect all sensors to do with fuelling, MAF included.

Thinking about this, my problems started not long after I did a boost leak test where I failed to block off the PVC so I was burning oil for a few days afterwards. Possibly I've contaminated the pre-cat lambda so it's now giving dodgy readings?

Anyone know how to test the lambda through Vagcom?


----------



## EnthusiastOwned (Mar 14, 2014)

EnthusiastOwned said:


> Another update.
> 
> I managed to get a brand new genuine n249 valve relatively cheap so I'm going to try that at the weekend.
> 
> ...


Another update. N249 did naff all :lol:


----------



## fixitagaintomoz (Apr 26, 2013)

Lambda then?

On the plus side youve replaced all the weak links, so once its sorted you'll be set for a while!


----------



## EnthusiastOwned (Mar 14, 2014)

fixitagaintomoz said:


> Lambda then?
> 
> On the plus side youve replaced all the weak links, so once its sorted you'll be set for a while!


Yeah, at least that's the plus side!

Do you think lambda could be the culprit?


----------



## fixitagaintomoz (Apr 26, 2013)

Its possible. Might be worth giving it a clean?


----------



## FRAX (Jul 21, 2013)

I would not have thought so but ye never know, as far as I know there are 3 lambda sensors and one of them is a bit of a pig to change.
There is not a lot left to check now -


----------



## EnthusiastOwned (Mar 14, 2014)

Tell me about it..

So Samgilding came around today so we can look at his jerky acceleration (turns out it's a coilpack). But it meant we can compare cars as I didn't really have anything to compare the way mine drove to. First things first my cars idle was noticeably lumper - more so by the feel and acoustics of the car.

We tried his MAF in my car and went for a drive where I thought it drove better, although it still had a lumpy idle. I then took Sam out in my car with my MAF and he couldn't really tell a difference in performance (I still feel like it had flat spots). The likelihood is it was in my head. Either way, I can strike the MAF off the list as the cause of my main issue.

What we did notice is that my idle became more lumpy as the car became hotter. As in from cold, fine. When warm is starts and when up to temp the lumpiness gets worse. After a hard drive the lumpy idle became worse (harder drive = hotter engine?).

So to confirm: My car definitely has a lumpy idle which get progressively worse as the car becomes hotter. The car seems to behave and pull as it should when driving (part and WOT).

So to date I have replaced:

N75
N249
MAF
Plugs
DV
PCV
Suction Pump
Pancake valve
Green Temp Sensor
Brake Light Switch

I've also checked and changed where required:
N75/DV hoses
TIP
Actuator hose
FPR hose
N249 hoses
all hoses under inlet manfold
crank breather hose
cam breather hose
physical coilpacks
coilpack physical wiring
N75 physical wiring

So guys, I'm at wits end.. Where do I go from here? [smiley=bigcry.gif]


----------



## neil_audiTT (Sep 1, 2010)

Compression test? Only reason i ask is to make sure it's not going between the cylinders.

I feel for ya man, mk1 TT is a bloody lovely car to drive and a QS should be special to be in!

One of those things you changed should have done it, end of. Lambda is the only other thing that might be confusing the ECU into thinking it's running differently than it actually is.

My first mk1 225 had a lumpy idle, and i never got down to the bottom of that - I rolled it before i found the answer :lol:

My next course was to compression test it.

I'm off ADI next weekend, probably coming back sunday. Could pop over if you're in and have a tinker.


----------



## EnthusiastOwned (Mar 14, 2014)

neil_audiTT said:


> Compression test? Only reason i ask is to make sure it's not going between the cylinders.
> 
> I feel for ya man, mk1 TT is a bloody lovely car to drive and a QS should be special to be in!
> 
> ...


Yes! A second pair of eyes would be very useful. You still got my number?

Tonight I double checked everything. No fault codes with Vagcom. TB is adapted. I went through the lambda tests (both pre and post) and tested the cat. All passed and the readiness are all marked as passed.

Strangely tonight I've had the car idling for 30 mins and it behaved fairly well. So bizarre.

The more I think and do research the more it think it's still a vac/boost leak. I'm wondering if I've missed something?


----------



## neil_audiTT (Sep 1, 2010)

Haven't got ya number anymore bud, but i have your FB! Long time since the polo days :lol:

That's all i was gonna pop down and check really, Vac lines. There's so many on the 20vt it's probably worth checking them all again, I helped a mate check through his boost leaks and vac hoses and there was so many that'd deteriorated over the years, one after another was failing. Fix one, find another!

Your brakes always feel strong though dont they?

Brake performance dropping off is normally a good sign of a vac leak!


----------



## Matt B (Apr 8, 2007)

Have you got a boost gauge ? Vacuum should be about 20 inches Hg


----------



## EnthusiastOwned (Mar 14, 2014)

neil_audiTT said:


> Haven't got ya number anymore bud, but i have your FB! Long time since the polo days :lol:
> 
> That's all i was gonna pop down and check really, Vac lines. There's so many on the 20vt it's probably worth checking them all again, I helped a mate check through his boost leaks and vac hoses and there was so many that'd deteriorated over the years, one after another was failing. Fix one, find another!
> 
> ...


It really is! I'm old now! 

I've gone over all the vac pipes but you never know really. Brakes are nice and strong so don't think it's the problem with the servo lines.



Matt B said:


> Have you got a boost gauge ? Vacuum should be about 20 inches Hg


Don't have one


----------



## EnthusiastOwned (Mar 14, 2014)

EnthusiastOwned said:


> neil_audiTT said:
> 
> 
> > Haven't got ya number anymore bud, but i have your FB! Long time since the polo days :lol:
> ...


----------



## fixitagaintomoz (Apr 26, 2013)

HI Mate, I'm just wondering if the inlet manifold gasket, or Injector seals could be causing your issue at all? maybe a little out of the box, but maybe there is a tiny leak and as it get hot that gets worse?

I might be talking nonsense but it's one of the few things you haven't got on your list of replaced parts, so maybe worth a go?


----------



## samgilding (Feb 5, 2014)

One thing I can suggest that I didn't think of on Saturday - buy a cheap boost gauge off ebay that ony requires a vac feed to run, t it into fpr hose and then just watch the gauge when the engine is warmed up to see if a vac leak is causing the problem. Once your done you can just run a new length of vac hose from manifold to fpr.


----------



## brian1978 (Jul 10, 2013)

You seem to have Checked everything, bit of a long shot but could corrupt ecu software or a bad ecu cause it. Might be worth getting the ECU flashed if nothing else works.


----------



## EnthusiastOwned (Mar 14, 2014)

fixitagaintomoz said:


> HI Mate, I'm just wondering if the inlet manifold gasket, or Injector seals could be causing your issue at all? maybe a little out of the box, but maybe there is a tiny leak and as it get hot that gets worse?
> 
> I might be talking nonsense but it's one of the few things you haven't got on your list of replaced parts, so maybe worth a go?


Funny you should say that. I just dropped off an inlet/TB for blasting and picking it up/fitting it tomorrow with new gaskets, injector seats and o-rings. Hmmmm..



samgilding said:


> One thing I can suggest that I didn't think of on Saturday - buy a cheap boost gauge off ebay that ony requires a vac feed to run, t it into fpr hose and then just watch the gauge when the engine is warmed up to see if a vac leak is causing the problem. Once your done you can just run a new length of vac hose from manifold to fpr.


Might be worth it. Although the boost seems good when using Vagcom. Requested and actual seem pretty close.



brian1978 said:


> You seem to have Checked everything, bit of a long shot but could corrupt ecu software or a bad ecu cause it. Might be worth getting the ECU flashed if nothing else works.


Possibly. It's not an avenue I want to explore though. Eeeek!


----------



## fixitagaintomoz (Apr 26, 2013)

I would suggest keep my fingers crossed then, hopefully its the gasket! Wont cost you any more than you were going to spend to find out!


----------



## EnthusiastOwned (Mar 14, 2014)

fixitagaintomoz said:


> I would suggest keep my fingers crossed then, hopefully its the gasket! Wont cost you any more than you were going to spend to find out!


Yep. hopefully. The gasket was out of stock at TPS so I'll have to pick it up at the weekend and wait until then before I fit it.

I have got my inlet back all fresh and blasted. I'm going to give it a lick of paint whilst it's out anyway. Crackle Black 8)

Just need to get the bloody injector inserts out now! Any pointers anyone??

What I have noticed is, I swear when I last removed my current TB it rattled when shook. The replacement one I have just had blasted doesn't rattle. I'm not sure what's normal? [smiley=book2.gif]


----------



## fixitagaintomoz (Apr 26, 2013)

Shouldnt rattle i dont think... ill go shake mine and see bud


----------



## fixitagaintomoz (Apr 26, 2013)

Mine doesnt rattle and mine ran fine...

Ding ding ding we have a winner!!!


----------



## EnthusiastOwned (Mar 14, 2014)

Hmmmmm... Let's hope so eh!

I'm wondering if the mech has broke so it can't alter idle?


----------



## fixitagaintomoz (Apr 26, 2013)

Might explain things, you can always swap the tb over now and see?


----------



## EnthusiastOwned (Mar 14, 2014)

Final Update..

It's fixed!

I would say air leaks were the main cause and dodgy MAF wiring.

I stripped the inlet, charge pipe, all aux pipework off again, inspected everything I could again.

I found a very small intermittent leak on the N249 to DV hose - I had two hoses with an adapter in between and it looked like the adapter had a split in it which intermittently opened depending on atmospheric conditions (usually opened up when hot), I changed this for a 1 piece hose.

The inlet, TB and charge pipe were spares I bought from a BAM engine (Same part no as the BFV) which I painted in crackle black. I renewed the gaskets, seals, seats and jubilee clips. The jubilee clip from the turbo to outlet hose was dead as it slipped when reaching a good grip. The TB to inlet and inlet to head gaskets had been reused too many times so weren't sealing as well as they could. But I think the main culprits were the injector seals as you could see residue especially around injector 4, the seals I replaced them with were a tad larger which has helped seal them - apparently there are two types of gaskets so it's important to get the right ones. The injector seats were a waste of time, pain in the arse to get out and re-fit and looking at the originals they would have been fine.

After all of the above was put back on, the car idled even worse than before, seriously misfiring, sounded gassy and struggling to keep running; great. I thought something wasn't right and I've caused a huge air leak. So I did a very comprehensive boost leak check and found nothing, everything was sealed and nice and tight. On a whim I ordered a new MAF and shut the car in the garage for the night. Then I had a thought, the TB was untested so I put my original back on and the car went back to normal (the poor idle, but better than before).

(The replacement TB incidentally does work, after removal I stripped it down and reset the butterfly as I had removed it for cleaning - this was the issue as it couldn't close properly).

Then the replacement MAF arrived, fitted this and nothing, no change. Great. I found a post of VWVortex about MAF testing with vagcom and followed the guidelines, my values were way off to what was expected. The values between the two MAFs were almost identical so I swapped back to my original. I then stripped back the wiring for the MAF and found one of the female connectors was loose in the housing. Hmmm. I sorted that, plugged the MAF back in. reset the ECU and pwarp, even worse idle then before, but the car felt better when driving, much better; like it had the full power and torque again- no more intermittent boost. I then reset the ECU again using vagcom, then the TB and performed all the engine readiness checks, boom. Smooth idle and smooth power.

So it was a combination of air leaks and dodgy MAF wiring. Yay!


----------



## Large Package (Oct 12, 2014)

Wow, sounds like the fault finding was a bit of a ballache [smiley=bomb.gif]

Glad you managed to sort it all out & she's running all good again


----------



## neil_audiTT (Sep 1, 2010)

Holy moly :lol:

Now to start enjoying it. Practically a new car now Rich :lol:

Sent from my Nokia 3310 using Tapatalk


----------



## fixitagaintomoz (Apr 26, 2013)

Happy for ya mate, glad you got to the bottom of it in the end!


----------



## chisharpe (May 27, 2017)

having a similar issue but my idle isnt lumpy it just fluctuates 720-760 and its annoying me! :evil:


----------



## 1781cc (Jan 25, 2015)

chisharpe said:


> having a similar issue but my idle isnt lumpy it just fluctuates 720-760 and its annoying me! :evil:


I have the same thing after my wak map, and even though I have replaced all the hoses and the maf its still there. Might have to delve a little deeper and check the maf wiring


----------



## SPECSMAN (Oct 11, 2016)

Top marks for sticking with it AND extra bonus points for posting the answer for us all. [smiley=cheers.gif] [smiley=thumbsup.gif] [smiley=mexicanwave.gif]


----------



## chisharpe (May 27, 2017)

1781cc said:


> chisharpe said:
> 
> 
> > having a similar issue but my idle isnt lumpy it just fluctuates 720-760 and its annoying me! :evil:
> ...


Fixed it yet? :lol:


----------



## Gtturbo (Jan 7, 2017)

Send injectors off for flow testing and cleaning then order new genuine orings from tps

What is your ltft in mvb 032 in vagcom after a 30min drive?


----------

