Gti6 Stalling When Coming To A Stop (Still!)

[2052006 10]

Since fitting my gti6 engine about 6 years ago, one of the few problems I have never been been able to solve is it stalling on occasion, always when hot and always when coming to a stop (junction, roundabout etc). It often occurred when I had parked it for a short while, got back into it whilst engine was still hot, and then it would stall, as I slowed down at the first junction I came to, having set off again. It would then seem to sort itself out more often than not.

 

Now, I know the obvious thing is the ICV. However, it has done this since I first fitted the engine and that was with a brand new, genuine ICV fitted (indeed, searching old posts, I found one from about 6 years ago, with me asking the very same question!). It's also nice and clean.

 

Mostly, it was not a problem and did it so rarely, that I never got round to fully solving it. It was worst when doing track days, where it obviously got very hot and it would hardly be able to idle, without a bit of throttle.

 

It was suggested that a failing VSS could cause this issue, but a different second hand one, and now a brand new, Valeo item, has made no difference.

 

I also have a brand new, genuine TPS fitted and engine CTS too.

 

However, I recently did nearly 3000 miles round Europe in it, and it got worse and worse - it was stalling all the time when coming to a stop. It was very hot in terms of ambient temp (30+ often) , but was also being driven very hard (Alps etc), for long periods of time and I would imagine under bonnet temps were very high.

 

Basically, it stalls when putting the clutch in, as I come up to a junction/roundabout in anticipation of having to stop, and always does it when hot - never when cold - and this is how it's always been. Yet I also found that it would sometimes cut out if I pressed the clutch whilst rolling (say doing 40/50 mph) and sticking the clutch in - it would cut right out (again when hot).

 

Seeing as it is clearly heat related could it be the Inlet Air Temp sensor (one of the few sensors I haven't changed)?

 

Or anything else? (I realise the best option may well be to try another ICV, but for the reason above, I'm not convinced that is the problem).

 

Thanks,

 

Pete

 

 

[rikky 37]

If this was in a 306, I'd probably be likely to try lambda next, or ICV rubber o-ring seal, or then unplugging the PAS sensor (probably doesn't apply to you here)

Edited July 19, 2015 by rikky

[2052006 10]

Brand new lambda, brand new MAP sensor, ICV o-ring seal appears in decent condition. You are correct - PAS sensor has never been connected (I presume this wouldn't be the cause i.e. it not being connected?).

 

Does anyone know what other sensors cause the ICV to operate (or not, in this case)?

[ade 4wd 11]

Are you able to read the ECU for any fault codes?

[2052006 10]

Unfortunately not. I did keep (iirc) the relevant wires coming from the ECU and multi-plug, but guess I would need to wire in a plug/connector. It was actually out of a phase 1 VTS, how were their ECUs read, via an OBD port?

[Paul_13 212 1 Cars]

Try unplugging the vss and see what that does

[Dizzee stuff 33 1 Cars]

I have heard of people having stalling problems due to PAS sensors, try having a search on google, you may need to install a resistor if your not using PAS.

 

check this out http://www.306gti6.com/forum/showthread.php?id=152176 1 of many results after a quick search.

Edited July 20, 2015 by Dizzee stuff

[2052006 10]

Try unplugging the vss and see what that does

Won't that cause other running issues though? But yes, it's one to try.

[2052006 10]

I have heard of people having stalling problems due to PAS sensors, try having a search on google, you may need to install a resistor if your not using PAS.

 

check this out http://www.306gti6.com/forum/showthread.php?id=152176 1 of many results after a quick search.

I am running PAS, just don't have the sensor plugged in (and can't as I used that particular wire in the loom for something else iirc). I thought the PAS sensors just caused issues when plugged in (if they're up the spout) and the only issue one might have when unplugged, was the idle dropping too low on full lock? Or have I got that wrong?

[Dizzee stuff 33 1 Cars]

The ecu uses the sensor to adjust the idle to account for the increased load placed on the engine by the power steering pump. You can always run new cables easy enough.I dont think pug would have put it there for nothing.

[Paul_13 212 1 Cars]

Yes it may cause running issues but it's one to rule out

[ade 4wd 11]

The PAS connector can be left unplugged if not used as the sensor on the PAS high pressure pipe is just a pressure switch. The switch can be either on or off.

If you put a wire link across the two pin connector on the loom the engine revs should rise a little..

I would try what has been suggested and disconnect the VSS to see what difference that makes.

[2052006 10]

So,

 

VSS disconnected, but no difference. Still stalling when hot at random times as described above. It also gave low rev running issues, as in a "flat spot" at low speeds/revs, which I believe is the usual symptom of the VSS not being connected.

 

Additionally I've now tried:

 

New ICV. Ordered a supposed Magneti Marelli (which is what I have currently) one from Carparts4less, but it arrived as a Meat & Doria one. Tried it, no difference, in fact stalling seemed worse. I did reset the ECU first too. So that M&D icv has been sent back. For info, the M&D one had a plastic housing, rather than the metal one of the MM and in general seemed of inferior quality. Does anyone know where I can get a genuine MM one from, I can't seem to find one anywhere (apart from Pug I suppose, but that will no doubt be extortionate).

 

New Inlet Air Temp sensor - as it was only a tenner - no difference.

 

So am still rather stumped as to what is causing this issue. My next plan is to wire in an OBD socket and get the Lexia software/cable, see whether that points to anything.

 

But any further suggestions other than this?

 

For reference, the following have been changed/replaced recently:

 

MAP

IAT

Lambda

TPS

ICV

VSS

[dobboy 231 2 Cars]

There's a fault finding doc on the net somewhere that describes symptoms and cures, in most instances the ECU coolant temp sensor pops up as a possible candidate. I changed mine for peace of mind (green with yellow ring), might be worth a shot, and you've changed nearly every other anyway.

 

I'd probably check resistance of coil packs to and make sure they are all within pug parameters to rule a dodgy one of them out.

[jackherer 543]

Does anyone know where I can get a genuine MM one from, I can't seem to find one anywhere (apart from Pug I suppose, but that will no doubt be extortionate).

 

Pug RRP is £131.78, I sold a new one on ebay recently for £90! They seem to be fairly sought after.

 

Dobboy, I've had a couple of coils fail recently on my 406 Coupe, I measured the resistance of the two failed ones and a new one and they were almost identical, one was slightly higher than the good one and the other was slightly lower but there is no way you'd be able to spot a dead one with a multimeter.

[2052006 10]

Jackherer - How did you know they had failed - just because of misfire or the way it drove I suppose?

 

Dobboy - It also has a new CTS, forgot about that one!

[jackherer 543]

That was on a V6, it was very underpowered and shaky, clearly running on five cylinders and the engine management light was on. I plugged my snap on scanner in and it reported a faulty coil both times.

 

The CTS is something you can test with a multimeter BTW, just measure resistance and temperature then cross reference it to one of the graphs or tables you can find online.

[oldkiteman 6]

You definately need to wire up a diagostic connector,Ive just done mine.It neednt be hard wired,just clip it on when needed.Only 4 wires,live,earth and connect to wires 140 and 141.If its got a green 2 wire connector next to the ECU plug,Check the wire numbers.on mine,the green wire was 140 and yellow 141.I connected the live feed to terminal 16,earth to 4,140 to terminal 7 and 141 to terminal 15 on the diagnostic connector.

On mine the stalling was caused by a rich mixture due to the fact that i had wired up the MAP sensor wrongly.

Another thing to do would be to check the exhaust CO and have the inlet smoke tested for air leaks.

Without doing this,you are like a blind man looking for a black cat in a dark room that isnt there!Rob

[petert 586]

Sounds like a classic too lean at idle syndrome. If it had a carby you'd adjust the mixture screw. Perhaps it has an air leak or a dead O2 sensor.

[2052006 10]

I doubt it's the lambda, that's brand new, and it did the same before, again even when the old lambda was brand new too. Both genuine Bosch ones too.

 

Air leak is a possibility though. However, It is very intermittant. Also I have had the entire car apart in the meantime, engine out etc and it's still the same. I will have to check the manifold and associated bits very carefully though, that is on my list, as well as getting the diagnostic capability up and running. Seeing as it's definitely heat related in some way or another, could it be something heating up, expanding and then causing a leak? Does that ever happen?

[dobboy 231 2 Cars]

Just a thought regarding air leak, have you checked the resonator box/connection and screws.

 

Do a marlboro light test!

[Paul_13 212 1 Cars]

Whip the inlet off and check it's not cracked.

I've managed to crack one before and I've no idea how

[2052006 10]

Update time on this problem.

 

Did a track day in it a few weeks ago. I was sure this would reproduce this stalling problem due to the high temps on track (as it's done before on track), but it didn't stall once! Not on the drive there, back, or whilst at the track. The only change I made was fit my oil cooler, but I can't believe this would allow it to run cooler, whilst on track, than on the road without the oil cooler. Most confusing.

 

I have also wired in an OBD plug and got Lexia to work - the only fault code showing was the purge canister. Now, I have never had the purge canister solenoid/valve plugged in, as I was led to believe this wasn't necessary. I just blocked the pipe up on the throttle body. However, on plugging the purge valve in, the fault code disappeared and it certainly changes the way the engine revs - albeit I have only tested this with the car stationary at the moment - I'm not in a position to drive it yet. When revving the engine with valve connected (by this I mean just the electrical connector plugged in to the valve, none of the actual pipes - the throttle body pipe is still blocked up), the engine seems to hold on to the revs less (i.e. drops back down faster) and also appears to have a more stable idle. Without it plugged in, the revs would often drop too much and it would almost stall (and sometimes would).

 

So the question is, what do people normally do with these purge canister valves? Should they be connected or not?

[dobboy 231 2 Cars]

funny you should say that. A 106GTI owner told me to get the sensor plugged in on my 205gti6 and tuck it away somewhere. I might just do that.

[Tom Fenton 1,541]

It is a valve not a sensor. The ECU determines if its present or not by looking for a small resistance across the coil inside the solenoid. You can either plug it in electrically and leave the pipe connections open, or a neater way is to solder a suitable resistor into the loom so the ECU thinks a valve is there.