Bad cold start, what am i missing

G

Gtirjoeynew

Member
So my car has an inherrant bad cold start/cold running issue i have had this issue for years with many parts changed and rolling road session never coming up with any answers.
basicly the car is a nightmare to start from cold and when i do eventually get it running any slight touch of throttle will stall it untill it warms up i can then being the throttle on gently.
The only thing ive never tried is the injector pack.
but this problem has stayed through the years even with engine changes, complete inlet changed including all the sensers/valves. Coolant temp switch changed complete ignition system, changed the fuel pump/ fuel tank.
 
PobodY

PobodY

Moderators
Staff member
Just because you haven't specifically mentioned it; have you checked the IAC valve since that's what gives you the cold start (well technically it's the AAC, but that's part of the IAC I think... or is it the other way around)?

Have you done diagnostic procedure 4 (from the service manual)?
  • Check fuel pressure. - Pinch the hose, and you feel pressure in the line?
  • Check AAC (which is a different procedure)
  • then Check injectors all fire when distributor turns.
  • then check spark plugs are firing.
  • then check the ECU.

Diagnostic Procedure 34 (Air Regulator):
  • Check fuel pump comes on and primes with ignition on.
  • Check power supply to AAC at the harness. (and/or continuity between the harness and earth)
  • Check resistance across AAC is approximately 10 ohms
  • Check plunger is not frozen or sticking.
  • Check spring is not broken.
  • Check FICD clicks when voltage is applied across it.

I'd give it all a good spray with throttle body cleaner to be sure; it might have just got a bit grubby.
 
G

Gtirjoeynew

Member
PobodY said:
Just because you haven't specifically mentioned it; have you checked the IAC valve since that's what gives you the cold start (well technically it's the AAC, but that's part of the IAC I think... or is it the other way around)?

Have you done diagnostic procedure 4 (from the service manual)?
  • Check fuel pressure. - Pinch the hose, and you feel pressure in the line?
  • Check AAC (which is a different procedure)
  • then Check injectors all fire when distributor turns.
  • then check spark plugs are firing.
  • then check the ECU.
Click to expand...
Ive checked plus changed it all mate, the fault has been carried all the through from a standard car to a car running 400hp had multiple differant management systems on it, and as you can imagine all the differant fuelling. Items that is required for this power.
even once it has fired it runs like a sack until it warms up.
 
B

BMCC

Member
PobodY said:
Just because you haven't specifically mentioned it; have you checked the IAC valve since that's what gives you the cold start (well technically it's the AAC, but that's part of the IAC I think... or is it the other way around)?

Have you done diagnostic procedure 4 (from the service manual)?
  • Check fuel pressure. - Pinch the hose, and you feel pressure in the line?
  • Check AAC (which is a different procedure)
  • then Check injectors all fire when distributor turns.
  • then check spark plugs are firing.
  • then check the ECU.

Diagnostic Procedure 34 (Air Regulator):
  • Check fuel pump comes on and primes with ignition on.
  • Check power supply to AAC at the harness. (and/or continuity between the harness and earth)
  • Check resistance across AAC is approximately 10 ohms
  • Check plunger is not frozen or sticking.
  • Check spring is not broken.
  • Check FICD clicks when voltage is applied across it.

I'd give it all a good spray with throttle body cleaner to be sure; it might have just got a bit grubby.
Click to expand...
It looks like from your post that the AAC and Air regulator are the same or are combined? I thought they were seperate units. The AAC controls the idle the FICD is used to up the idle when the air con is on and the Air regulator is on for a short period of time (till the heated bi metal plate closes) to provide a higher idle on warm up.

I would have thought diagnostic procedure 4 (EF-EC 530) Hard or impossible to start when engine is cold would be where to start? Then onto procedure 13 Engine stalls when stepping on the accelerator momentarily.
 
G

Gtirjoeynew

Member
BMCC said:
It looks like from your post that the AAC and Air regulator are the same or are combined? I thought they were seperate units. The AAC controls the idle the FICD is used to up the idle when the air con is on and the Air regulator is on for a short period of time (till the heated bi metal plate closes) to provide a higher idle on warm up.

I would have thought diagnostic procedure 4 (EF-EC 530) Hard or impossible to start when engine is cold would be where to start? Then onto procedure 13 Engine stalls when stepping on the accelerator momentarily.
Click to expand...
Thanks for the replys where are you getting these procedures from?
im willing to try anything as a car ive spent so much doe on, ive lost all love and intrest for over this in willingto give it one more go of fixing and if not i give up ill count my losses and break it
 
B

BMCC

Member
Gtirjoeynew said:
Thanks for the replys where are you getting these procedures from?
im willing to try anything as a car ive spent so much doe on, ive lost all love and intrest for over this in willingto give it one more go of fixing and if not i give up ill count my losses and break it
Click to expand...
Service manual which you should be able to download it from this site. There was a link somewhere. Maybe it was on the modifiers site?
 
Last edited:
G

Gtirjoeynew

Member
red reading said:
Who has mapped it?
Click to expand...
Ed mapped it last, once the car is warm it runs spot on.
also ive even tried putting the standard air flow, injectors and standard ecu on jus to give it a go and problem is still the same.
dont get me wrong this is not a problem that stops me using the car but it is an absolute pig to start and and when i get it going as i said it jus wants to try and cut back out its not misfiring or anything, although if i was to clean the plugs get the car running and pull them out after say ten minutes they are black as anything so its overfuelling i guess from cold, as they come out looking ok if i actually go and drive it and warm it up properly.

And cheers steve i will go through that in a bit see how it helps:-D
 
johnny gtir

johnny gtir

Well-Known Member
where the sensors you used known working ones not a chance one that was changed was also faulty or failed straight away
 
G

Gtirjoeynew

Member
johnny gtir said:
where the sensors you used known working ones not a chance one that was changed was also faulty or failed straight away
Click to expand...
Well they were used so i u never know i guess, today i tried a brand new temp senser was pretty sure it wasnt that but was easy so just changed it.
im thinking i should mabe try changing the valve that bolts to the bottom of inlet that water passes through again. I believe this is the valve for cold start?
 
Fusion Ed

Fusion Ed

Active Member
Gtirjoeynew said:
Ed mapped it last, once the car is warm it runs spot on.
also ive even tried putting the standard air flow, injectors and standard ecu on jus to give it a go and problem is still the same.
dont get me wrong this is not a problem that stops me using the car but it is an absolute pig to start and and when i get it going as i said it jus wants to try and cut back out its not misfiring or anything, although if i was to clean the plugs get the car running and pull them out after say ten minutes they are black as anything so its overfuelling i guess from cold, as they come out looking ok if i actually go and drive it and warm it up properly.

And cheers steve i will go through that in a bit see how it helps:-D
Click to expand...
I think I remember this, does the idle control work from the laptop, if it was mentioned to me at the time I would have tested it... Send me a PM and if I can find your map (I will have it) I'll see what your cold start looks like - usually it doesnt need changing but in some cases it does. Obviously when the car comes to me its already hot so I'm unable to see this for myself.
 
The Doc

The Doc

Moderators
Staff member
What shape is the inlet pipe to the turbo? And what about running the maf blow thru (don't drive it like it on boost without mapping).
 
G

Gtirjoeynew

Member
Fusion Ed said:
I think I remember this, does the idle control work from the laptop, if it was mentioned to me at the time I would have tested it... Send me a PM and if I can find your map (I will have it) I'll see what your cold start looks like - usually it doesnt need changing but in some cases it does. Obviously when the car comes to me its already hot so I'm unable to see this for myself.
Click to expand...
Cheers ed i send a pm now it was quite some time ago you mapped the car.
 
G

Gtirjoeynew

Member
Once i get to the bottom of this problem there is a few other jobs that i want to do then it will be down to you for more boost and remap it will need to make it safe.
 
Fusion Ed

Fusion Ed

Active Member
Yep no problem. People should at least get the car Dyno'd yearly. Especially stuff like this, almost no one does that. I guess with the amount of pulsars I map they almost never give grief, yearly seems a bit to frequent haha :)
 
B

BMCC

Member
The air regulator uses coolant as a source of heat? From the manaul it says it has a heater circuit which is on all the time the eng is running. Is the coolant used to keep this from over heating then?
 
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