Misfire cylinder 1

[Clarkj93]

Hi guys,

So I added a full bottle of liqui moly cleaner to a full tank and soon the car started misfiring only on idle usually it seems, the mpg increased by quite a margin and feels fine to drive but it seems just on idle I have a problem. It may be a coincidence it happened after adding the cleaner but it's done a good 600 odd miles since and at least and 2 full tanks since with a decent "italian tune up" but it still persists and if anything is worse than before.

I've had the following codes:
Cylinder 1 misfire detected
System too lean bank 1
Evap emission incorrect purge flow

Cylinder 1 misfire appears fairly regularly after clearing and system too lean now and again, the evap purge flow only appeared once and never came back.

I've today just changed the n80 valve and the carbon cannister hoses because of the evap error and made no difference to misfire (was a long shot!). I've got some silicone hoses to replace the old boost pipes with but I can't see this fixing the problem anyway!

I've swapped the coils and plugs from Cylinder 1 to 2 and still only misfire on Cylinder 1. Just sitting in it now  watching the live data it misfires around once a second at least usually, but if I disconnect the MAF it seems to misfire then only about once every 5 seconds? Also I can see watching live data that the misfiring seems to stop once I apply any amount of revs (or at least if I hold a steady amount).

Anything else I can try before calling VW for a new fuel injector? Or is there a tell tale sign of the MAF on it last legs or maybe o2 sensor?

Cheers!

[mjmallia]

Not sure what miles you have done, but these cars with their age need a carbon clean from 80k miles upwards due to being direct injection.....caused a misfire on mine recently, and went after I did a carbon clean of the inlet valves (time consuming job!)

You could also have a lazy/faulty injector, worth checking and getting them checked/ cleaned if doing the inlet clean above

[Clarkj93]

Ah I read it barely makes a difference on these... yeah I think I'm getting to the point will have to get injector tested!

Changed the pcv in October but with just a cheap Febi one and Trw hoses, part of me is wondering if its buggered already, I should have bought genuine at the time really.

[bobby_fodge]

I bought a silcone pcv hose from ECS as the plastic one keep cracking with the heat over time.

https://www.ecstuning.com/b-ecs-parts/silicone-lower-pcv-hose-replaces-06f103235a/023473ecs02~a/

[Clarkj93]

I bought a silcone pcv hose from ECS as the plastic one keep cracking with the heat over time.

https://www.ecstuning.com/b-ecs-parts/silicone-lower-pcv-hose-replaces-06f103235a/023473ecs02~a/

Yeah I got this on my basket currently from awesome gti.

[pudding]

That is classic bad injector syndrome.  It's only noticeable at low injector duty cycles, hence a lumpy idle and possibly a surging/jolting part throttle when hovering between light throttle and overrun.

Your evap fault code might come back if you didn't also change the carbon can.  What tends to happen with those is they break up with age and little chunks of carbon can find their way into the N80 valve, jamming it open.  If that isn't the case, the carbon chunks might just be saturated with age, either way, you'll need a new can at a rather steep £100ish from VW.

[Clarkj93]

That is classic bad injector syndrome.  It's only noticeable at low injector duty cycles, hence a lumpy idle and possibly a surging/jolting part throttle when hovering between light throttle and overrun.

Your evap fault code might come back if you didn't also change the carbon can.  What tends to happen with those is they break up with age and little chunks of carbon can find their way into the N80 valve, jamming it open.  If that isn't the case, the carbon chunks might just be saturated with age, either way, you'll need a new can at a rather steep £100ish from VW.

A new injector it likely is then, are the other 3 likely to go soon as well or can I get away with just changing the one you reckon?

Great news on the carbon cannister as well, another thing to the list

[pudding]

Well, as they say, whilst you're in there!  You would give yourself a swift punch to the balls if you changed just one injector, and then another one failed 6 months later    Yes, I know, it's major £££s.....but it's better to do the job just once as intake removal is an utter, utter ball ache.

Give R-Tech a call, they usually have a circulation of refurbished ones which will save you some sheets.  I think they are a rather bum tensing £150ish each from VW at the moment.

Yup.  Welcome to TFSI ownership    Your car won't be happy until every last penny has been drained from your bank account....ungrateful b1tch!

[Clarkj93]

Well, as they say, whilst you're in there!  You would give yourself a swift punch to the balls if you changed just one injector, and then another one failed 6 months later    Yes, I know, it's major £££s.....but it's better to do the job just once as intake removal is an utter, utter ball ache.

Give R-Tech a call, they usually have a circulation of refurbished ones which will save you some sheets.  I think they are a rather bum tensing £150ish each from VW at the moment.

Yup.  Welcome to TFSI ownership    Your car won't be happy until every last penny has been drained from your bank account....ungrateful b1tch!

She has been far too reliable lately, should have known something would pop up! Will give r tech a call, thanks for the info. I can see rough quotes of about 60 quid to get injectors sent off and cleaned/tested. Not sure if this is more of a "service" to keep things running well or something that would fix a injector on its last legs?

[pudding]

Always the way!

As far as I know, they just change the filters and pintles and then flow test, but the main guts of the injector remains the same, so yeah, it's always a gamble between brand new lasting 7-8 years, or refurbished lasting, 3 maybe 4?

[Clarkj93]

Hmm, yeah will mull it over I think over the next week, not overly fond of giving VW 600 odd quid... thanks for the info again Pudding!

[Clarkj93]

Not sure if anyone's interested but been toying with this issue with little spare time I've had recently in between a couple other rust and paint related jobs. I'm in denial about fuel injectors currently as I can't be bothered with removing and sending off/fitting new right now, hoping for a miracle!

Changed the MAF, 145 quid from VW and annoyingly no change.

I've swapped the stock air box for a creation motorsport intake as I wanted anyway and it removes the issue being the intake, again no change.

I've cleaned the IAT which was looking a bit oily, no change.

I did notice a misfire in cylinder 2 and 4, though this only happened a couple of times while monitoring and is not really often enough to say its consistently intermittent. But could be a sign its not something specifically wrong with cylinder 1?

Before the misfire started the only thing I did was add the liqui moly and fiddle with the throttle body hose, I wonder if that is the issue? The hose does not fit that well but would appear to be securely fitted? It did actually detached while driving after fiddling with it again recently, I've binned the old ones and stuck some new clips on there, still misfiring but seems possibly less often? I do have a new silicone one to replace but it's an absolute bugger to fit so will give it another go when I've had some weetabix along with cleaning the MAP as well.

I've got a suspension refresh to do also so while I'm ordering bits from awesome gti will grab a new pcv and gasket, ECS pcv hoses and a oem revision G diverter valve just for general maintenance if nothing else, may get lucky though!

[pudding]

Misfiring and/or a lumpy idle has always been the bain of petrol engine owners 

I don't know what it is with cars you own.  They never seem to idle smoothly compared to mates' old beater sh1t box Vauxhalls and Fords they don't care about 

Anyway, did you look in measuring block 032 to see what the long term fuel trims are?  They normally creep up and up if there's an air leak, which can cause misfires.

If the fuel trims are tiny numbers, it's probably the injectors and/or carbon build up.

Need to get all the hardware ship shape first before calling it though, such as sorting loose throttle hoses etc etc.

[Clarkj93]

So I thought I found the issue here:


Not an easy part to source, I read that vw charge well over 100 quid for this brake booster and the cheap ebay ones are 45 odd quid and like other ebay parts destined to break. So bought some samco 9mm silicone vacuum hose, very carefully cut the old one off and stuck the new one on, comes to the grand total of 9 quid so cheap easy fix!



Car is definitely running much smoother, however it is still misfiring annoyingly! Thought I had it!

 I don't have vag com but do have obd-eleven, pretty decent for a 50 quid thing, although it's by no means the complete package and does have some shortfalls as I show below. This video really helped with what you mentioned:

Obd-eleven just kept showing 0 percent or failed to connect for 032, 033 however showed quite high numbers and started rising from the point of ignition:



I noticed the upper pcv valve hose is loose, and hissing a bit, I disconnected it pcv side and stuck my thumbs over pcv hole and the end to the hissing hose, the number dropped to well into the negative figures. Note that  I did this while the engine was running and doesn't sound great when it almost stalls and almost sounds like there is some knock going on when doing this, could just be my ears though. Anyway... ordered some silicone hoses for pcv a while ago but order is delayed until end of the month, just bought a cheap 10 quidder on ebay for now as hopefully that will just prove to myself if that is the issue or not and can replace with the silicone one when it arrives. We're getting there! Slowly!

[Clarkj93]

Final update then. Replacing the upper pcv hose did the job, it was just a cheap ebay part so I think after replacing the brake booster vacuum line I broke a seal on this hose while fiddling with it, another ebay part proved it was the weak point and running smoothly now! Got some ecs silicone ones to replace these coming in a week or 2 as the permanent solution.

 Cheers for all the ideas from everyone!