S2 coupe playing up.

[220bhp]

My coupe is behaving strangely at the moment. It has started to play up in traffic. it try's to stall, and its hard to keep it running. It seems to clear once you get going. I changed the maf the first time, and it seemed to fix it for a couple of days, but now its doing it again intermittently.
Another thing which may or not be connected is this gentle whistling sound at around 2000+ revs. You only get it if you are on part throttle
The car will still boost to 1.9,and I have done a leak test and cant find anything. Also checked the vacuum hoses. It sounds like its coming from the turbo, which I also checked for play, there is no movement in or out. or side to side, so that was a relief.
Odd thing is as my hearing is not up to much, along with the rest of me theses days, I asked my son and his mechanic friend to come for a drive so they could hear it, but with two other people in the car it wouldn't make the whistling sound, very odd. I am hopefully having the codes read this week so we will see what the computer says.
If anyone has any ideas I would be very grateful.

[mike74]

My one was starting to get a bit 'lumpy' while sitting in traffic but without trying to stall like you say. When the fan kicked in the revs would shoot up a couple of hundred RPM then re-settle to idle, same while fan was switching off (very annoying when crawling in first gear!). I took the ISV off last night and gave it a good clean with carb cleaner, WD40 & a couple of cotton buds. It runs a LOT smoother now. My one didn't even look particularly dirty when I had it off too! Definitely something to try as it only takes half hour tops to do and is effectively free. Can't comment on the whistle though but if it seems to drive ok & is boosting well then I wouldn't worry about it too much
HTH
mike

[Bowie69]

A whistle normally means a leak on the intake tract somewhere... and yes this will give symptoms you describe.

[UrS4boy]

N71 ISV info and Vacuum Line Info

My coupe is behaving strangely at the moment. It has started to play up in traffic. it try's to stall, and its hard to keep it running. It seems to clear once you get going. I changed the maf the first time, and it seemed to fix it for a couple of days, but now its doing it again intermittently.

You've already been given the hint on this one: N71 ISV. Click on the N71 label in the upper middle right of this diagram (you might want to book mark the diagram too as all the labels are live and lead you to more info about those engine bay devices).

http://members.shaw.ca/speedtek/UrS%20Engine%20Bay%20Device%20Map.html

[220bhp]

I have tried cleaning the ISV, no change. I also changed it for another one ,and still no change. The problem is not there from cold. Once up to temperature it goes like a scolded cat. boosts well and runs really well. The problem only happens when you slow down It then starts to try to stall. When I pulled into my driveway it seemed to be running on a couple of cylinders, I wiggled a few sensor wires, and the only thing that made any difference was when I moved the lambda wire. I am wondering if this could be it. Dan is coming round with vagcome tomorrow night so we will see.
Would the lambda cause this issue if the wires short out. I have a 3inch down pipe and it gets pretty hot down there.

[UrS4boy]

G62 ECU Coolant Temperature Sensor Info

You should check your G62 at the back of the head.

The G62 is a temperature-influenced variable resistance. The ECU drives out a voltage (5? 12?) to the G62 via ECU pin T45/55 via a Grey with Brown stripe (GY/BR) wire. The return current is returned to ECU ground pin 30 (presumably via a brown wire).

If the G62 fails, it *might* throw a check engine light (CEL). Blinking the code out (or using a VAG tool) would reveal:

2312 (Blink Fault Code), 00522 VAG1551/2 Fault Code Number
Coolant sensor (G62)
Open or short circuit, Defective sensor or wiring, high resistance between sensor G62 and ECU J220
Symptom: Cold starting difficulties at low temperatures, Poor idle and acceleration during warm up
(Reference SJM Autotechnik)

From Bentley, the G62 (Engine Coolant Temperature (ECT)) sensor test procedure is as follows:

Allow the engine to cool to room temp (68F/20C)
Disconnect ECT sensor from harness connector
Switch multimeter to resistance range
Connect multimeter to terminals 1 and 2 of the ECT
Resistance must be 1500 to 3000 ohms

IF NO = replace ECT
IF YES = check wiring between sensor and ECM (ECU)

Reference: Bentley pg. J28-22

http://forums.quattroworld.com/s4s6/msgs/20985.phtml

Base photo courtesy of Tom S.

[Colesy]

I have tried cleaning the ISV, no change. I also changed it for another one ,and still no change. The problem is not there from cold. Once up to temperature it goes like a scolded cat. boosts well and runs really well. The problem only happens when you slow down It then starts to try to stall. When I pulled into my driveway it seemed to be running on a couple of cylinders, I wiggled a few sensor wires, and the only thing that made any difference was when I moved the lambda wire. I am wondering if this could be it. Dan is coming round with vagcome tomorrow night so we will see.
Would the lambda cause this issue if the wires short out. I have a 3inch down pipe and it gets pretty hot down there.

I had similar issues which only went away when I changed the lambda. In theory the lambda shouldn't cause this but in my case it did. The only codes I was getting related to the MAF. On closer inspection the wire into the lambda was slightly frayed from rubbing on the airbox.

[220bhp]

Now that's a possibility: thumbs:
Thanks to all for your help. Very much appreciates. I will post the vagcom results tomorrow .
I took the car out today, and there where no real issues, apart from a loud pop through the exhaust on full boost. Other than that, just a little grumble around
2000 revs. the whistle is not so pronounced, maybe its me being a little paranoid, having blown a brand new rs2 turbo on some ****** chips. The sound is a spool up sound, like a gentle howl between 2, and three thousand revs. You only get it by pushing the pedal gently.

[220bhp]

Dan very kindly came round tonight to vagcom my cars. First my wife's 2.6 cabby, which came up with two faults. 00554 lamda lower limit intermittent. The second simply said, 17978 see other version, what ever that means. Then we tried the s2 and it refused to read it, saying interface not recognised. We tried Dan s2 and got the same result .Tried the cabby a second time , with no results. Is it possible that the free rosstec download only allows one car per given time.
We took the s2 out tonight and apart from one loud misfire through the exhaust, it seems to be ok for the moment.

[newsh]

When's the last time you checked your dizzy timing?

[newsh]

Free vagcom works fine, never had any issues reading multiple cars, did you unplug the lead and then plug it in a different USB port? That can upset it. otherwise maybe reversed on of the 2 pin plugs (quite easy to do with the cheap leads) and blew the fuse for the K line.

[CoupeWannabeS2]

Free vagcom works fine, never had any issues reading multiple cars, did you unplug the lead and then plug it in a different USB port? That can upset it. otherwise maybe reversed on of the 2 pin plugs (quite easy to do with the cheap leads) and blew the fuse for the K line.

I did plug the lead in the wrong way when plugging it into Lou's car. Does that mean I have possibly blown a fuse in the Vagcom cable, or a fuse on the car? Sorry, I don't know what the K line is.

I did have the cable plugged in the same USB port the whole time, and it has worked well in the past.

[newsh]

The fuse in the car, I can't remember what fuse number it is though..

[newsh]

Fuse 21 I think.

[220bhp]

John I haven't checked the dissy timing since I had it mapped. What makes you ask that is it something I should do on a regular bases. Is it likely that it has moved or are you thinking crank pulley, or timing belt.
This problem is intermittent, even this whistle seems to have gone, [which I am beginning to think is a small exhaust leak somewhere] Dan drove the car last night, and we couldn't hear it. So I don't think its related.
I did fit a new set of bosch plugs a few week ago, which Seem to be suspect theses days
So it might be an idea to change them. Also I think a lamda change might be a good idea after all those early running problems. I have changed most of the other parts chasseing the problem including the temperature switch on the back of the head which
Dave mentioned.