Pt 2 cold starting problem - Is my ECU the problem??

[manfred]

In part 2 of my VR's starting problem, could it be my ECU the main crutz of it all?? The car starts with no problems after the battery was replaced and also when battery was disconnected and then reconnected giving time the ECU to reset.

[kopper69]

ECU is normally pretty reliable. Are you saying shes running fine now?

[DannyboyDS]

No I think they are saying that it starts like crap, unless they reset the ECU then the first start is ok.

I'd assume another compnent is faulty and the ECU after being reset starts the car on a basic setup, then the faulty component sends it its signal or lack there of, the ECU tries to adjust and creates a problem.

Although then an error code would be logged.

[andyman]

take it for a long run like a 50 to 100k trip and see how it goes, i know with mine you have to take it for a good drive after disconnecting the battery for it to re adjust its parameters,

[manfred]

Could it be the actual Harmonic Balancer causing the problem in cold starting?

When my car went in for a service, the mechanic found a crack in the harmonic balancer. I don't know where on the harmonic balancer but he says it is there.

[ephect]

what exactly is ur "part 2 problem" ??

u havent listed what its now doin? i've read up on ur first issue and u said that it had been fixed?

is it still taking 5-10 secs to start? is ur car running like crap? u havent said what ur problem is? we need as much info to help us help u

what makes u think the ECU is at fault?? it could be a part thats failing, that makes the ECU run in limp home mode.. then resetting it, clears the fault code, making it run normal, until the faulty part logs a code again..

[kopper69]

Grab a manual mate and have a read. Will hopefully point you in the right direction. Even if it doesnt solve you problem, should help you check just about every component. Theres no point guessing is it ecu, is it harmonic balancer - youre clutching at straws.

[manfred]

I came to a conclusion that my ignition on the steering column is the prob 'cause for the 1st time in a long time I heard the fuel pump buzzed (fuel got up to pressure) and the car fired up with just a flick of the key today (24th April 2007). And to be sure I done it a couple of times and again a flick with the key and it started straight away. Also noticed that my engine check light didn't flash once and lit up, but lit up only once before starting.

[304cci]

engine coolant temp sensor?
On cranking the ecu looks at the coolant temp sensor to decide how long and fast the fuel injector paulse should be. If it is incorrect the air fuel mixture will be incorrect for a cold start, and it will flood.

[manfred]

Had my mechanic look at the cold start problem on my VR commodore V6 and he came to a conclusion its my EFI relay causing the problem due to the fuel pump not getting the correct voltage through the relay contacts so that the fuel pump makes a whirl noise in the fuel tank, giving the correct fuel pressure in the fuel rail before cranking over the engine.

[kopper69]

That problem sounds a little strange. So replaced the $15 relay and shes going good?

[manfred]

The Auto Elect. today (Mon 7 May) replaced the EFI relay as what my mechanic said...made no difference. Then after lunch I had a call from the Auto Elect saying if I had a key for the car alarm (Mongoose) which I replied no I haven't so the alarm was removed.

Then when I picked up the car this arvo, the guy said its a wierd fault but is narrowed down to 3 things in following order:-

1. The immobiliser
2. The ignition
3. The ECU

And to add the guy said when he used the remote on the central locking the car had a hard cold start for a few seconds till it fired and ran/idle, whereas when lockin the car by only using the door/ignition key there was no problem in starting (immobiliser on or off state wasn't mentioned in conversation).

So to find out what is what over the next 3 days I'll be doing the following in order:-

1. Use remote to unlock/lock doors (immobiliser on - locked doors / immobiliser off - unlocked doors)
2. Use key only to unlock/lock doors with immobiliser off

Question is what am I to look out for when I do the above tests??

[manfred]

I've been doing further digging into my car cold start problem and the outcome is that my ECU is the culprit due to it is unable to hold a charge (a capacitor) for it to remember (memory) as storage. The hint of this when I disconnect my new battery and reconnect it making the ECU resetted and it starts and idles/runs perfect with a quick turn of the key and then the next day the the same problem of starting the car returns (takes about 10 seconds to crank over and then it runs/idles).

[kopper69]

Nah, I dont think so mate. The ecu is going to be an expensive one for starters. Definatly worth getting a second opinion first.

The ecu does not need to 'hold charge'. Power must be maintained to the ecu from the battery in order for it to retain its settings. If you disconnect the battery, you reset the ecu to default values. As long as you arent disconnecting the battery, the ecu should still retain its values.

I would be guessing a sensor playing up. Have you tried checking the error codes again?

I would maybe suggest its time to go to a holden dealer. It will be a little more expensive, but they should be able to determine the problem for you, even if you dont get it fixed by them.