Help Please - Intermittent engine start then immediate stall issue

[amcleod1]

Hi all.

I'm hoping someone can help me with an intermittent engine start then immediate stall issue. I have searched this site and found some useful posts/info which I have followed and replaced a number of parts as suggested by the posts but problem remains.

Car is a stock 2000 VTII Calias with GENIII 5.7L V8 engine. Engine has 190,000km on it. Regularly serviced. No oil leaks. Runs 98 octane fuel. Never missed a beat before.

Problem / Symptoms:

The engine will start normally on most 1st attempts without issues - just by turning the key.
Sometimes the engine will start normally on 1st attempt but with very low rpm that builds to normal idle rpm within a few seconds.

Randomly however, say one out of every 10 first start attempts, the engine will crank and kick-over normally, but then immediately stalls
Most times it will then start and run on next start attempt
Sometimes it may take several re-start attempts
When it does start:
- sometimes it starts with very low rpm that builds to normal idle rpm within a few seconds
- sometimes I've had to floor or pump the accelerator pedal on the re-starts to get the engine to run
- sometimes turning the key from ON to START does nothing on re-start, no fuel pump priming, or start soleniod clicking in (have to turn key all the way back to off before engine will crank again)


Once started and running engine appears to run normally. The only abnormal running things I've noticed are:
-Idle is a little rough - vibrations felt throughout the car (occurred before and after new engine mounts recently installed.)
-Under heavy acceleration power is not applied smoothly - engine hesitates then power surges. This hesitation/surge occurs from standing start, and at speed following auto-transmission-kick down.
-Generally I'd say power overall for a 5.7L V8 seems low to me, but it has done some miles now.

So problem is best described as an intermittent engine start then immediate stall issue. Problem occurs randomly - I haven't established any sequence of events to force the problem to occur. It happens with engine hot or cold. You can hear fuel pump prime for 2 secs or so when key is first turned to ON. I had Holden connect a Tech-2 and it pulled no codes whatsoever.


I've replaced the following parts, one at a time in order, and driven the car:
1. Replaced Battery - problem still exists
2. Replaced Start and EFI Relays - problem still exists
3. Removed and cleaned IAC Valve and connection - problem stills exists
4. Replaced Crankshaft Angle Sensor - problem stills exists
5. Cleaned MAF Sensor - problem stills exists
6. Plugs and leads replaced - problem stills exists
7. Fuel injector petrol additive - problem stills exists

I know my pass-side intermediate muffler has a collapsed or loose baffle - expensive part to replace so not gone there yet.
Haven't replaced the IAC valve - again expensive to replace.


My current thoughts are that it could be:
- A fuel delivery issue (fuel pressure, clogged/dirty fuel filter, lines and injectors); or
- Some form of electrical issue or
- the intermediate muffler or
- the IAC valve

http://forums.justcommodores.com.au/images/smilies/idea3.gif Appreciate any suggestions or next steps to diagnose fault cause.

Thanks in advance.

 

[amcleod1]

Update: As luck would have it, I was able to capture the start/stall issue on video. I've posted up to youtube at Intermittent Engine Start - YouTube

This was one of the worst examples to catch on tape. It shows 12 start attempts in trying to get the car started for first time for the day. Once started and running, a further 6 or so starts off video were perfectly normal.

Attempts 1 - 3: Nothing, car was dead, no starter motor activiation at all.
Attempt 4: Cranked, no kick over
Attempt 5: Cranked, kicked over and immediately stalled
Attempt 6 - 7 : Cranked, no kick over
Attempt 8 - 9 : Cranked, kicked over, ran for a moment and stalled
Attempt 10: Cranked, no kick over
Attempt 11: Cranked, kicked over, ran for a moment and stalled
Attempt 12 (inside the car) : Started and running

 

[amcleod1]

Another update....with some feedback from those on the ls1.com.au forum I can have a lead and can now force the fault to occur everytime.

It looks like it could be the lack of a circuit being made between the nipple on the key and the ring around the ignition switch which does not disable the immobiliser. So I tried an experiment today - I left the car stopped and unlocked for a few hours. I put a couple of layers of electrical tape over the contact nipple on the key, inserted the key so the tape insulated the key from the ring and tried to start the car. Presto, I was able to generate just about everyone of the symptoms I mentioned above. Then, with the tape still in place, I depressed the unlock button, it started first time and ran fine. This process is completely repeatable on both keys.

Having read more of the VTII workshop manuals the theft system automatically locks the ignition down (immobilises) after 30 seconds after the engine is stopped whether you use the key to lock it or not. Further, the only ways to disable the theft system to start the car once immobilised is EITHER to use the key to UNLOCK the car OR via the circuit the key makes with the ring on the lock. If so, it could well be that the contact on my keys are worn, or the ring in the ignition lock is worn, or both or something playing-up in the wiring from the ring to the BCM.

So I'm going to give it a couple of weeks now to hit the unlock button every time immediately before starting the car to see if that resolves the problem. Will update this thread then.

 

[Nut Kracker]

Reading through your first post, I was thinking ignition switch. But you have seemed to have worked that out. Well done and good luck with it.

 

[stocknotmock]

I recently had the exact same problem my advice if anyone else has stall and no restart problems the first (and free) thing to do is try unlock until the immobiliser is disabled evidenced in the red light stopping its flash sequence just above the mode on dash.I fell likely you will need to re key this vehicle eventually as I did but just pushing unlock while key was in the ignition salvaged the situation for me for a few weeks. It wad right here in these forums I diagnosed the problem with the guidance.

 

[BlackoutSteve]

I have almost the same issue with my WH Caprice LS1.
Only happens when it's a hot restart.
Always takes 3 attempts to start.

With mine, the engine fires each of the 3 times then immediately stalls.
As expected, pumping the accelerator pedal does nothing.
The fuel pump has been replaced recently (with a GM/Delphi unit).
The alternator has been replaced very recently and then this issue disappeared for about 3-4 weeks, but now it's back again.
I thought the alternator swap was a clue, so all heavy electrical connections were double checked..

Anyone got any ideas?
Perhaps the key fob connection?

 

[amcleod1]

Hi All, mine turned out to be a really simple fix - something you'd never think to check - its was the alarm system doing its job. The issue was the key was NOT making contact with the metal ring that goes part way around the ignition lock when the alarm was armed. It would it start every time the alarm was first disabled by pressing the unlock on the key and starting within 30secs of the press. However after 30secs or so the alarm auto-arms if car not started. Normally, you can still start the car with the key after 30seconds as the key has a nipple on it that when turned in the ignition lock makes/stays in contact with the metal ring - if it does not the car starts then stalls. The reason for the intermittent nature was the key can be inserted either face up or face down in the lock - one way it worked every time. The other way always start / stall as no contact was being made. Fixed by gently bending the metal ring out a bit to ensure good contact. FIXED.

 

[BlackoutSteve]

That makes sense.. I'll pay close attention to that..
This could be why I've been thinking it's a hot restart issue, because in most -perhaps all cases, I think the key has remained in the ignition with the engine off for more than 30 seconds..
Thanks for the heads up.

 

[jrv1964]

Hi guys, I had this same issue with my wk v6 supercharged Statesman, it was doing this intermittent "first startup" then stall within 30 seconds issue" requiring a restart or two to get it to idle and it would do. this more on hot starts. I found the circular small contact knob on the remote key fob had pushed in so far that it was not making proper contact with the circular outer ring ( the one that spring loaded ) when the key was inserted into the ignition switch. I had to open the remote key fob, pull out the little knob ( its just held in there with a spring clip and these get loose resulting in the little contact pushing into the fob-also a lost a screw out of the fob holding the key part in which did not help, so I tightened the spring clip with pliers, pulled out the contact knob or point and put a new screw into the fob ) and that has fixed the problem, so check your remote key fob for that too, also check it for dirty contact, hope that helps.