Overfuelling + stalling!! Help please?

[RichieP]

I've been trying to sort a fuelling problem I've had for a while, and am in desperate need of advice before I go completely nuts.
Symptoms are:
Usually starts from cold reasonably (takes 5-10 seconds of cranking to get going, but it's been like that for years)
Idles ok, and if left will continue to do so for between 5-15 minutes, then stalls with a strong smell of fuel and won't re-start (turns over, strong fuel smell - doesn't fire)
If started and driven from cold, it runs well for 3-15 minutes, then stalls, and either won't start as before, or will after lots of cranking + stinks of fuel. Drove today - fine for approx 3 minutes, then stalled doing 30mph in 3rd, engine light on, no error codes logged. Left for 15 minutes it reluctantly re-started and limped home producing white, fuel rich exhaust fumes. During the rare patches that it runs ok, the exhaust looks/smells normal.

What I've done:

Plugs are new
New CTS
New coil packs
Injectors removed, tested and re-built by a reputable specialist
Fuel pressure regulator swapped for another one I had spare
Elanscan shows appropriate values for CTS, manifold temp, air pressure, manifold pressure and injector pulse width

If I leave it for half an hour, it usually re-starts and I'm back to square one
Help please!!!
Thanks
Richie

[ailwyn]

Have you checked your air intake for blockages? Clean air filter? Base timing?

[RichieP]

New K+ N, base timing checked. I've had the inlet pipe off the plenum, which didn't make any difference. Did get a slight waft from the flexible pipe when the engine was revved suggesting all was clear between the turbo and the engine.

Just been fiddling again - should the secondary throttle close its self before the engine is cranked? I assume I'm looking at the right thing - the mechanism visible between 2 and 3's inlet tracts. I assume that it's normally open and closes under vacuum. My engine's cold again, so will start. This mechanism doesn't move until the engine's been running for a couple of seconds. The idle doesn't seem to settle until it's done this as well?? Could this be part of the problem?
Thanks
Richie

[RichieP]

Could someone have a look at their secondary throttle and let me know how quickly it closes on start-up? Mine is staying open for 3-5 seconds after it (reluctantly) fires up - is this normal?
Cheers
Richie

[RichieP]

I'm cautiously optimisitic that I've solved my main problem - a new set of plug leads was indicated when I tried to double check my base timing, and only got an intermittent strobe flash despite it idling smoothly.
Now runs well and doesn't seem to be producing the fuel smell in the exhaust, but is still a bit reluctant to start!
My secondary throttle is still not closing until 3-5 seconds after it fires up - I've tested all the vacuum lines and the solenoid valve but found no fault. Could this be the cause of the starting problem, or is this just how they work?
Cheers
Richie

[RichieP]

HELP!!!

It's happened again - done 20 or so trouble free miles, then suddenly the engine died while driving - plumes of white smoke coming from the exhaust. I was doing about 35 in 3rd so left it in gear to see if it'd fire up again, blipping the throttle, but nothing! Pulled over and turned the ignition off for a couple of minutes, then it started again, was a bit smokey for a minute then settled back to normal!! Ideas anyone?
Would a dodgy connection to the CTS cause it to flood enough to die completely, or is an ignition failure more likely?
Any ideas for an intermittent total ignition shut down?
Please help!!

Thanks
Richie

[ailwyn]

Plumes of white smoke are a bad sign, sounds like coolant is getting into the cylinders... which is likely to be a head gasket issue.

Ailwyn

[RichieP]

I thought that initially, but the smoke only happens transiently. The rest of the time it's fine, even under boost. When it did it this morning it coincided with the engine cutting out (almost as if the ignition had been switched off - I'll be looking at that later), almost like there was zero spark and the injectors on full?
Richie

[ailwyn]

I would expect plumes of black smoke f it's unburnt fuel, white smoke to me signals water.... although I could be wrong... I suggest you get a pressure/sniffer test done, that should rule out HGF between the cylinder and coolant system.

[RichieP]

I've just done a compression test and got about 140 psi on each cylinder (give or take 10psi - it's a slightly dodgy borrowed tester)
The plugs were quite sooty - they'd been cleaned and gapped about 20 miles ago, and one of them had a broken ceramic, so no more playing until tomorrow.
Any thoughts for trouble shooting intermittent spark failure on all cylinders on a car with new coil packs, leads and plugs?
Cheers
Richie

[RichieP]

I'm cautiously optimistic that I've cured my problems - I disconnected every connector I could find, sprayed them with contact cleaner/lubricant and reconnected them, then removed, cleaned up and re-fitted every earth strap under the bonnet (lots of fun!)

Thus far, no problems, but I have a question re. my hard-start issue: I've found that the secondary throttle is reluctant to close, and I'm sure this is connected to the problem.
If you do the paper clip thing to put the car in diagnostic mode, the solenoid that closes the secondaries is powered up when the ignition is on, but the engine not running. When I do this, I can hear the solenoid chattering, but the secondary stays open!
Is this normal?
If I press down on the actuator (the bit you can see between the inlet tracts) to close it manually, it doesn't stay fully closed and returns to about 3/4 open. When the engine is started it closes after a couple of seconds (when higher vacuum is available?)

I've checked all the vacuum hoses, replaced the vacuum reservoir and tried a different solenoid valve, non of which made any difference.

Any thoughts?
Cheers
Richie

[RichieP]

It happened again last night - total loss of power + plumes of white smoke from the exhaust. Ignition off for a couple of minutes and it was fine again. A friend of mine's just had similar symptoms with his fuel injected air-cooled VW, but not intermittent - turned out to be an injector that wasn't closing, but he described exactly the same clouds of pure white smoke with a strong smell of fuel - and no coolant to confuse the issue.
Am I back to looking at the fuel system over-pressuring the injectors? Aside from the pressure regulator, can there be any issues with the pump set up that could lead to over-pressuring?
Thanks!
(a rather desperate) Richie

[GeoffSmith]

Whip out the plugs to confirm how many pots it's overfuelling on. If it's only one, then suspect that injector. If it's two then suspect ECU drive circuit. If it's all four then suspect a common problem causing over-pressurising.

[RichieP]

It's all four - I left it sat idling this morning until it did it again - the usual clouds of white fuel vapour when trying to re-start it. All four plugs wet through!
When it was running, disconnecting the vacuum line to the fuel pressure regulator didn't seem to have much impact. I see there's a non-return valve shown in the return fuel line, but I couldn't see it under the bonnet - an pointers where to find it? Any other ideas for trouble shooting an over-pressure?
Thanks again
Richie

[Specky]

Just read this thread...

I'm thinking sensor.. possibly MAP

TTFN

[RichieP]

I've just sat watching ElanScan while starting/running/stalling etc. and can't see any problems with the numbers - the MAP is within about 5% of the absolute pressure reading, dropping to around 0.35 when idling at 1200ish rpm. There are no variations seen when it stalls then won't start.

Richie

[Gary]

All this sounds like the TPS to me. Smell of fuel too, but when mine went the paper clip test gave an appropriate message

[RichieP]

TPS readings on ElanScan are spot on. Also the IAC seems to vary appropriately to maintain idle (ie if you hold the engine revs up using the throttle, it closes and opens again when you close it). Thanks though!
Richie