Corrado 24v misfire - help please

[quicky1980 0]

Car start and idles fine, and very light throttle up to 2000rpm and is fine however applying more throttle causes the engine to misfire dramatically enough to not allow revs to hit 3000rpm or above. The misfire almost feel/act like a derate or rev limiter, with occasional backfire. See video

http://s144.photobucket.com/albums/r180/quicky1980/?action=view&current=MOV_4429.mp4

I fitted brand new audi coils x 6 last year, spark plugs and a new water temp sensor too last year with around 6-10k miles use. Did a quick check by disconnect the coils from each spark plug and each cylinder made the note change

 

I checked the spark plugs and they are black which isnt a surprise as the car stinks of fuel.

 

I've attatched the latest scans. But am a noob with what is all means. Any experts opinions?

 

The issue occurred since having the ecm tweaked by SWICT due to the ecm not adapting (all carried out while the car was stored over winter. Mark at SWICT said hes confident its not the tweak or ecm at fault but Im unsure tbh. Speaking with Mark he's a bit lost with it all too and so am open to any suggestions, ideas from you guys.

 

Throw yours ideas in as I'm open to all possibilities of the problem and methods to fix it. thanks ahead of ti,e

ecm scan.pdf

ecm scan b.pdf

[24V Renshaw 0]

Check the crank sensor. I had this when I first built and installed my 24v in my previous C. It was just a bit loose as I had not tightened it properly...

 

Jay

[quicky1980 0]

hhmmm, maybe. Ive not touched it but it may have come loose. Did you have these same symptoms Jay? Where is it found, same as the 12v?

Edited April 12, 2012 by quicky1980

[24V Renshaw 0]

Yeah I had the same kind of symptoms.

Check your plug gaps too as that can really throw the 24v.

 

Jay

[quicky1980 0]

just popped out and had a quick look. the sensor looks snug but I cant get to the plug to check. Will need to take the front end off. I checked the plug gap and set to around 0.8mm

 

---------- Post added at 9:17 PM ---------- Previous post was at 9:11 PM ----------

 

will look to replace this then if youve had similar symptoms. I would have thought an error code would have popped up though :shrug:

[Kevin Bacon 5]

You can't properly diagnose this with a shareware version of VAG-COM. The errors it is telling you can be ignored, but only seeing 4 of 17 errors isn't really helping us.

 

The engine wouldn't even run if the crank sensor was at fault, so it's not that. I'd get it over to Vince personally!

[24V Renshaw 0]

Kev I can 100% guarantee you it would run if the crank sensor was working but not in securely. This is obviously not the cause in this case if it's in properly but it gave me the exact symptoms on my 24v, hence my suggestion.

I do however agree about the scan software. You need proper codes to diagnose it.

[Kevin Bacon 5]

Hmmmm. OK. The relationship between ECU and crank sensor is it works, or it doesn't work. If a loose sensor was still within tolerance (i.e. the air gap), the ECU would be happy with that. It wouldn't run the engine too rich because it's a bit loose. It can either see the signal and synchronise, or it can't. Something else was causing the over-fuelling.

[24V Renshaw 0]

It must have been a dream..

 

Jay

[quicky1980 0]

Speaking to SWICT, the suggestion is that fuel pressure has changed. Ive not touched the FPR but maybe is come loose or changed flow? will give that a check.

[Kevin Bacon 5]

Good call. Do you have a fuel pressure guage? R32s need to run at 4 bar. Has the vacuum feed come off your FPR?

[quicky1980 0]

not one on there but I should have one lying around. Will give this a check and was set at 4bar last time but may have change (or even failed).

 

vacuum feed looked fine.

[quicky1980 0]

checked fpr and pressure was actually slightly low at around 3bar, raised it to 4bar but still have issues. could the low fuel pressure have caused this issue??

[Kevin Bacon 5]

That was static pressure, i.e. engine not running? Well R32s should be 4 bar anyway, so that's sorted, but I doubt it's what's causing sooty spark plugs. Sounds like the ECU is over fuelling rather than a mechanical issue. A sensor out perhaps. Without seeing all the codes it's hard to tell. With the engine running, try unplugging things like the coolant temp sensor, the cam sensors and MAF see if it makes a difference. Could also be the lambdas as you've had issues there before IIRC?

[quicky1980 0]

pressure was measured whilst running. What codes do you need to see mate as I've attatched the read out I took on my first post. I would try swapping out sensors but some are expensive (cam shaft sensors are over £100 each!)

 

I did have coil pack issues a while back but I dont think I had lambda sensor issues (again these are newish and expensive to swap out)

 

I will try disconnecting the sensors but am thinking that this wouldnt show up the problem necessarily? iirc Ive done the cam sensors and they caused the engine to die, maf made no difference, lambdas. but will try again methodically this weekend.

[quicky1980 0]

didnt get chance to pull plugs out over the weekend. but am starting to loose hope. would gladly appreciate phone support or hands on support to help diagnose the issue. current thinking is a sensor is faulty but not being shown up on scans, but i have no idea how to check without having to swap out with new (expensive) parts.

 

i'm more than happy to cover costs etc to anyone who can help.

 

---------- Post added at 12:41 PM ---------- Previous post was at 12:20 PM ----------

 

just taken the plunge, getting a mobile auto electrician out to have a look at it. :epicfail:

[Kevin Bacon 5]

I'm sure it's something simple. I have the full version of VCDS and can help diagnose it. I don't have time to drive all the way to Peterborough this week though. Is it drivable?

 

EDIT: After the mobile electrician has been round and failed ;)

[quicky1980 0]

Thanks for the offer. Maybe if the auto electrician has no luck I'll take you up on the offer. plus you know your stuff with these engines etc.

 

I had a look and the lambda part numbers and they are below, do these seem right? If I had wrong ones fitted would i get these symptoms. i ask as SWICT did some "tweaks" to the lambda data iirc, just wondering if these are now incompatible??

 

---------- Post added at 7:11 PM ---------- Previous post was at 6:33 PM ----------

 

a little confused here, my lambdas were picked out by TPS last year but differ in part number to these

http://www.ebay.co.uk/itm/AUDI-TT-3-2-V6-LAMBDA-SENSOR-022906265-NEW-AUDI-PART-/140538455876?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item20b8bea744#ht_1025wt_954

http://www.ebay.co.uk/itm/AUDI-TT-3-2-V6-LAMBDA-SENSOR-022906265A-NEW-AUDI-PART-/380334446804?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item588db318d4#ht_1025wt_954

 

have I got the wrong lambdas fitted?

[Kevin Bacon 5]

TBH I don't know mate as I don't use the OE lambdas on mine but I do remember Rob's (Heresites) R32 running like poo as well when he had the wrong lambdas. I'm pretty sure they need to be the right ones for the ECU but I don't know the p/ns or exact details I'm afraid.

[quicky1980 0]

hmm, the plot thickens!

[quicky1980 0]

well the lambdas were a direct fit so that idea fell out of the window. Auto electrician had a look around and couldnt see any issues (although tbh he didnt seem that clued up)

 

took the car out for a blast and at first the car was a pig, but after a couple of tries it got better but still has a misfire but now at a higher rev range. at one point all but one cylinder was firing, but on engine restart all cylinders purred, reved hard and again down to one cylinder but fine after restart...wierd!

 

could the fuel be off? the car was sat for a few months over winter with half a tank of tesco unleaded. guys at work said this could be the cause :shrug: Im a little surprised if fuel can go "off" that quickly but cant rule it out. thoughts from you guys?

[Kevin Bacon 5]

Fuel doesn't go off to the point of causing a misfire mate and even then, not just on one cylinder ;)

 

Sounds to me coilpack related. Have you got the latest recall coils? The R32 has misfire detection and the full version of VAG-COM would tell you which cylinder ;) :lol:

 

You could check the old fashioned way and hoik the plugs out. The dark and sooty one will be the culprit.

 

I am prepared to come up with my laptop and some coils if you don't get anywhere with it.

 

Somewhat foolishly of me I suspect, I am considering going ME7 on mine too, lol, so it's all good experience. That's the thing with the OE mangement though. It's fine it works, but when it doesn't, it's a right royal pain in the arse to sort.

[quicky1980 0]

I have the latest coils on and I even did the old fashioned check to see which ones could be faulty (all fine except for the wierd time that killed 5 cylinders until the engine was restarted). last week i checked the plugs and they were all black but Im told that this may be because the cars has been idling for so long

 

looking online, and speaking to a few people, unleaded can loose octane in around 1 month and become pretty bad around 6months. My car has been sat up since sept and would mean that the half a tank of fuel would have had chance to age around 6months (plus the time before being laid up) so this could be the issue. should be easy enough to check this theory out as Ill run a line from the lift pump into a spare tank and stick a bottle of clean new fuel in and take it for a blast to the local petrol station.

 

You may be right and its not "bad" fuel related but I'm getting desperate and trying every avenue. I'm just worried if I take it for a drive I may cause myself more issues/damage to the car.

[Dox 23]

See post 96, you can view cam timing and the sensors themselves with VCDS with measuing blocks 208 and 209.

 

http://www.r32oc.com/general-chat/9621-timing-chain-4.html

[Kevin Bacon 5]

IIRC, he has a MK5 engine which came with the upgraded chains from the factory. That check is only relevant to MK4s. Good shout though.

 

Sam, my V power was over 6 months old when I fired my R32 up for the first time and that DEFO loses octane, but it ran peachy :D