Gti6 Stalling When Coming To A Stop (Still!)

[dobboy 231 2 Cars]

2052006, as per Tom, can you measure theresistance for me and let me know what color the plug is?

[2052006 10]

Dobboy, my multimeter needs a new battery, but the plug is brown (2-pin), located around the area of the throttle body on my loom.

 

Just need to drive it now, see if it solves my issue...!

[dobboy 231 2 Cars]

any joy?

[2052006 10]

Jack - not entirely sure what I'm doing with a multimeter and measuring resistance, but set to 200, it gives a reading of 26.3. Hope that helps?!

[dobboy 231 2 Cars]

Yeah, ideal, sounds like a 25ohm resistor should do the trick.

 

Cheers 2052006!

[2052006 10]

Dragging this up again for an update. Having been SORNed for most of the winter, I've recently done a lot of mileage on it. Plugging in the purge canister valve has definitely helped stabilise the idle when hot. Marked improvement when hot, in traffic, town etc. So, most of the time it is as it should be. However, it appears it's not fully solved the issue:

 

It will still, randomly, stall when coming up to junctions/roundabouts - having slowed, and once put clutch in, revs drop and engine just dies. Interestingly, it will also do this when moving at speed - for experimental purposes - put clutch in, revs fall, but it is not caught at idle - they just fall and engine cuts out. It immediately bump starts no problem when I engage clutch again! Does this suggest anything specific?

 

It only seems to cut out like this, if I've been using little to no throttle for a little while, before disengaging clutch. If it's had a good thrashing (i.e. lots of on and off throttle) it never seems to stall.

 

Every engine sensor is either brand new or has been replaced in the past year. ECU swapped. New coils. Lexia shows no faults. Inlet manifold has been taken apart, resonator checked, new gaskets, throttle body cleaned.

 

I'm pretty much out of ideas. Anyone got any other suggestions??!

[welshpug 1,657]

I'd borrow a wideband lambda, see whats happening, might be going lean like peter says, so may be fuel pump.

[Anthony 1,003]

I'd borrow a wideband lambda, see whats happening, might be going lean like peter says, so may be fuel pump.

Surely at idle and after being on overrun is exactly when it wouldn't be the fuel pump? If the pump was so bad that it was leaning out at idle then it would be unusable under load and high up the rev range where the demand for fuel is much higher.

[Toddy 7]

1) Try driving with the Lambda plug disconnected, uses base settings, could be a dry joint to the lambda heater wiring.

 

2) replace the loom

Edited May 10, 2016 by Toddy

[2052006 10]

Anthony: That's what I thought. Is it the case that the fuel pump "pumps" at a constant rate? Is it the FPR that then regulates the amount of fuel going to the injectors? In that case, would it be more likely to be the FPR, if it is a fuel problem?

 

Toddy: Yes, I should try disconnecting the lambda. Only thing is, it was pretty much brand new last year, when it had exactly the same symptoms. And replacing the loom is becoming one of the few options left, unfortunately.

Edited May 11, 2016 by 2052006

[Anthony 1,003]

Fuel pump delivers a constant flow of fuel, the fuel pressure regulator restricts that flow to maintain fuel pressure at 3 bar above manifold (i.e. it'll be lower than 3 bar at idle) and then the ECU controls how long the injectors are open for and thus how much fuel is injected.

 

Failing fuel pumps usually show up in the mixture going lean at high revs/load, because they can no deliver the volume of fuel required.

[2052006 10]

So is it possible that the FPR could be at fault, or is this unlikely, in the same way that it's unlikely to be the fuel pump if the engine is fine at high revs/load? I'm just thinking along the lines that it only seems to stall when manifold pressure is lower (?) i.e. little to no throttle having been used, and this somehow affects the FPR which is operated by the pressure in the manifold?

[Anthony 1,003]

FPR seems a little far-fetched given how intermittent the issue is, but certainly it's worth ruling out.

 

I've a spare one that you're welcome to borrow when you drop the ECU back - indeed, I should have a complete inlet manifold with all the associated bits if you want to rule most of it out in one hit.

 

I'm starting to suspect that it might be a loom related issue somewhere. Certainly I've seen one GTi-6 converted 205 that would intermittently stall when the clutch was dipped which was solved with a replacement loom, but that one also intermittently showed the tale-tale flat spot pulling away so I'm guessing that one had a broken wire somewhere on the VSS wiring that would intermittently break the connection and give the flat spot and stalling issues common with VSS related faults.

[2052006 10]

OK, thanks Anthony, I'll be in touch re the ECU/manifold. I should probably do that before removing the whole loom again.

 

I'm fairly certain though, that whilst experimenting last summer, it still showed the same symptoms with the VSS unplugged - though with the addition of the flat-spot. And I don't get that flat-spot now, with the VSS plugged in. Of course, that doesn't mean it's not a fault in the loom somewhere I suppose.

[dawning 11]

Was talking to the guy in the peugeot dealership today, he was saying that the gti's used to cut out how you describe because the alternator could not generate enough current with all the electrics running. Just an idea.. he said they always started back up fine but they used to put bigger alternators on to stop it happening.

[2052006 10]

Rich, was that 306 gti6s he was referring to or 205 gtis? Though in my case, it doesn't seem to matter whether I've got lights on etc...

[petert 586]

Have you tried disconnecting the vacuum from the FPR? This will give a flat 3 Bar at idle, richening the mixture slightly.

[dawning 11]

It was the 205 gti''s, apparently they used to fit the desil alternators with a higher amperage. Said it happened when people had lights/wipers/radio all on. I just thought as you said it did not happen so much when you thrash it it may be because it's getting charged more. possibly a more complicated electrical issue leading to the same problem. I am not usually one to give out advice however so take it with a pinch of salt good luck with it though

Edited May 12, 2016 by dawning

[2052006 10]

I thought I'd get a multimeter on it anyway:

 

Battery (only a few months old) shows just over 12v with engine off. At idle it shows 14.36v.

 

However, as I switch on electrics - headlights, de-mister, fog light, stereo, interior fan, and finally engine fan (when up to temp), the reading falls to 13.45v. I was under the impression, the voltage should remain the same? Then, with this reading i.e. all electrics on, if I give it throttle, as revs fall back down, it'll almost cut-out, but (apart from one or two occasions), manage to catch and bring itself back up to idle speed. Voltage shows 12.5v, when it appears to be about to conk out.

 

I then took it for a test drive down some long steep hills, so that I didn't have to use much throttle and would put clutch in, at say 40ish mph. With no electrics on, I could not get it to stall, on several occasions of trying. Then with all of the above mentioned electrics on - it stalls. Not every time, probably about 50% of the times I tried.

 

So, does this point towards a duff alternator? Should the voltage remain the same with electrics on? (The car never has any problem starting btw).

[jackherer 543]

The voltage is definitely too low, if you're seeing 12.5v when it is running there is a problem for sure.

 

Before condemning the alternator itself I would check the wiring to the alternator and battery including grounds.

[2052006 10]

Well, it shows 12.5v when it is *about* to stall i.e. when it is turning over very slowly. It either catches it and goes back up to idle and 13.45v, or dies. With this in mind, is 12.5v still too low?

[jackherer 543]

When you say turning slowly do you mean really slowly, like a few hundred RPM or do you mean a normal idle speed? If it's turning very slowly before the voltage drops then it's just a symptom but if it is only 12.5v at 900/1000 RPM or higher there is a charging problem IMO.

[2052006 10]

No, it's below idle speed - as it's almost about to stall. Like you say, I think 12.5v is just a symptom, of it turning over at very low rpm.

 

But should the voltage drop as I turn on more electrics?

[welshpug 1,657]

itll drop slightly but should come back up snd stabilise

[2052006 10]

Well it definitely doesn't go back up, until I start turning off the various electrics...