Starting trouble, any ideas?

[LHD_Kid]

This was in a thread I started with various running problems. most has been sorted now apart from this damn starting trouble...
When cold or after the car has been left for more than 2 hours or so it fires immediately, but runs like $**t for 30 seconds or so.... you have to rest your foot on the throttle to stop the engine from stalling.....
If you try to drive off while the car is running a bit rough it will stall...
it misses, coughs and splutters, then after 30 seconds it runs perfectly, no issues at all afterwards, ful power, right through the rev range (obviously only try this when warmed up properly)
I have tried the following so far, but would be grateful of any advice...
Compression test, showing 9.95 BAR on each cylinder (205,000 Kms, not rebuilt)
changed plugs, leads, dizzy cap and rotor arm (this cured my on power running problem)
started it last night, drove it foir 5 minutes until it was running sweetly..... parked up and removed the expansion tank cap, theory being any pressure would then not force coolant into the bores if HG was at fault... (compression test points away from HG though doesnt it?)
This morning went out, replaced cap and started the car.... just as bad as before, misses and coughs....holding revs at 1500 on the throttle it clears reasonably quickly, but something is obviously wrong...
What is it?
I struggle to get parts here, so any tests I can do to eliminate or highlight a possibility wthout changing parts would be good....I can get parst sent if it points to a definate culprit...!


Thanks
Chris

[Jas11n]

Leaking injectors? Stuff like this isn't a strong point for me, but just a thought.
Hmm, if I've thought of it, then bet it's already been mentioned and ruled though

[LHD_Kid]

Yes, I have thought about this, but dont know how to test it...
I dont have anywhere to take them to have them flow tested or checked or anything...
I was wondering about driving the car and then depressurising the fuel system then trying to startup the next morning, so that the car would have to psuh fuel into the injector area before .... but would this mean it starts badly anyway?
I would like to know if there is a foolproof way for me to rule them out?

[iain1067]

I think you can take them out, check the spary pattern for one thing in a glass jar, or take them out and place them in 5 seperate jars overnight and see what fuel leaks out, pulling a spark plug before starting might give you a clue, is it wet with fuel???? and does the cylinder smell of fuel???

iain

[iain1067]

This is from bentley for the s4/s6 may help

Fuel injection quantity and leakage, checking

Requirement

System pressure OK

- Disconnect vacuum hose from fuel pressure regulator.

- Disconnect harness connector(s) from fuel injector(s).

- Disconnect fuel intake line and lift out upward (with fuel injectors).

Note:

Always use new fuel injector seals, moistened with clean engine oil. Take care not to damage the seals during installation.

- Connect one terminal of each fuel injector to be tested, to engine Ground (GND) using adapter cable from VW 1594.




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- Connect second terminal of fuel injectors (one at a time) to remote positive cable connectors, using remote control VW 1348/3 A, adapter lead VW 1348/3-2 and auxiliary cable.
- Connect VAG 1598 Test Box to Engine Control Module (ECM) harness connector using adapter cable VAG 1598/5 Page 01-73 .
- Switch ignition ON.
- Bridge Test Box terminals 3 and 10 using adapter and inline fuse (8A).
Electric fuel pump must run
- Check fuel injectors visually for leaks.
Not more than 2 drops of fuel per minute (maximum) is allowed to leak from each cylinder.

If fuel leakage is greater:

- Switch ignition OFF.
- Replace leaking fuel injector(s).
- Replace seal(s).




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- Hold fuel injector to be tested in measuring glass from fuel analyzer VAG 1602.

- Operate remote control VW 1348/3A for 30 seconds.

Output must be 150-170 ml (5.1-5.7 oz.).

If measured volume from one or more fuel injectors is above or below specified volume:

- Replace faulty fuel injector.

Note:

Always use new fuel injector seals, moistened with clean engine oil. Take care not to damage the seals during installation.

[iain1067]

Note they are quite specific about the seals


iain

[iain1067]

Plenty more reading here

http://www.sjmautotechnik.com/trouble_shooting/20vboost.html

Noapte buna

Iain

[4WheelDrifter]

Try leaving the car as normal. Then disable the ignition and remove the spark plugs. Turn the engine over on the starter and see/smell what blows out of your bores.

[LHD_Kid]

I am assuning that petrol should come out anyway.... right? so... one might have more coming out than another? Am I looking for a cloud out of a bore?
I am a numpty for sure, but would kindof like to know what to expect...!
I think I did this before on an old Nissan, to see if any water had made it through the air intake after a flood got to roof level...
Is this to see if its petrol or water causing the problem?
Thanks for all the help...

[4WheelDrifter]

Water, fuel, oil, ....? I dunno. Just don't stick your head over the engine when you do it. Get an assistant to do that.

[LHD_Kid]

Get an assistant to do that.

Now that....... is a good idea...!
Cheers, will give it a try tomorrow...!
Chris