5L V8 Stalls during normal driving

[jon_vs]

My 5L V8 Caprice drives well, starts without problem. However, while driving sometimes the engine just stops - the engine warning light comes on followed by the rest of the dash lights. I wait about 15 to 20 seconds or sometimes more, turn on the ignition - I hear the fuel pump prime and most often it starts (sometimes it needs a second crank) - idles normally, runs normally so off we go again. I may not have the problem again until the next time I use the car.

I have checked the error codes and only get "12" – telling me that everything is OK. Within the past 50,000 klms, I have replaced the coil, ignition control unit, hall sensor, leads, distributor cap, fuel pump - all this was to chase and fix an earlier problem (the hall sensor). The problem is intermittent but it is becoming more regular.

The car always starts from cold and hot. When I had the previous problems with the Hall Sensor it was (always) more of a starting problem than a running problem.

[Troy5L]

are all the hoses hooked up? u might have a leakin vaccum hose..

or even, turn the car on and when its idiling tap the MAP sensor, if the revs bounce when u tap it then its fault and might be causin u some problems...

maybe go over the coil, ICU, hall sensor, leads n dizzy cap and see if everything is ok...if u still cant find the prob i guess droppin into a mechanics and seeing if they can find the problem...good luck man

[Dinwoodie]

Hey mate this seems to be a common problem happening with 5.0L's around now, i've spent hundreds on fixing the solution to mine (i was having the exact same problem as you) and after spending a heap of coin it came back to a $60 hall efect sensor in the dizzy, hope this helps and saves you some effort, peace

[jon_vs]

Hi Troy5L
Thanks for your thoughts. I have checked the vac pipes - all seems well. I have tapped the MAP sensor with no noticeable effect on the revs. Disconnecting the MAPS vac pipe certainly produces an effect. I checked out the electrical components as you suggested but could not find any “obvious” problem. Unfortunately the stalling problem is such an intermittent one. It is going to be hard for any mechanic to find unless he has had a previous similar experience.

[jon_vs]

Hi Dinwoodie,
Thanks for your reply. The last time i had a starting problem I also spent heaps in time and $, and yes it was the hall effect sensor. However, that time it produced very different symptoms to what I am experiencing now ( they were intermittent, not starting and then sometime after minutes, hours - what ever "it" felt at the time, the engine would start as if there was never a problem. The engine would never "stop" once it was running.) Now I am not having any problems starting, but heaps of problems stopping!

[BlackVXGTS]

Did you replace the coil? In my experience they just stop working altogether but it might be worth a try.

[jon_vs]

Hi BlackVXGTS - I checked back over last 70K or so - the coil has been replaced.
Here's an UPDATE - I have spoken to 4 mechanics, the first not a clue but willing to quote on it, the next two passed the buck and the fourth (also an auto electrician) recons it could be the ICU rather than the HES (in his experience), so he has suggested to replace the ICU first. Hmmmmm. The car performed faultlessly yesterday (must realise that I'm onto it!). At the end of a run I touched the ICU and it was hugely HOT (easily >70 C). Is this normal?

[hako]

Maybe try replacing the fuel pump relay....or at least swap with another on the relay block. Also check the fusible links - make sure they are connected tight. I don't know about the ECU getting hot though I'd imagine they would get rather warm just like a PC.
Good Luck.

[vnss5ltr]

i would just leave it for a little bit. as much as you can bare. i have had similar problems and they can just be a result of circumstance. give it a few days, see if it clears up, if not find a serious mechanic. i love mechanics who have no clue, defeats the purpose

[jon_vs]

Hi Hako,
Thanks - I have already tried swapping the relays to no effect and have also checked the fusible links - nothing there either. Meanwhile, Repco provide an exchange ICU for $255 and an exchange (new) HES for $105. Where the ICU is a breeze to replace, the HES is way more complicated to get to - who was the engineer who designed the placement of that one? I had a Jag once and its workshop manual said to remove the engine, first raise the bonnet (!!) I guess the Holden manual might say to remove the distributor, first remove the engine !!

[jon_vs]

UPDATE - Last night the same old problem happened - motoring along and the car just stops. However this time it was a little more difficult to start - it needed a number of attempts to crank it. Eventually it started (after ~5 mins) and we went on without problem for the rest of the evening. I checked the error codes this morning and found that number 46 was logged. I have since found two references for code 46 ...
Ref 1. "No reference signal from ignition module while cranking"
Ref 2. "No reference signal while cranking"

I am sorry for the stupid question -

ref 1. says "from the ignition module" Does this imply an ICM problem (?)
ref 2. could then imply HES problem.

All comments will be greatly appreciated.

[levymetal]

check the plug on the HES, sometimes that can come loose. in the case where you have the dizzy out anyway i would strongly suggest that you replace it with a brand new dizzy to avoid problems in the future.

pretty sure stocky had a similar problem to what you are describing, turned out to be the coil. if it's been 70,000kms may as well give that a shot. the casing may have a slight crack which is all you need to give you a stall here and there. for $70 it's a good place to start.

a guy on ebay also does reco ignition modules for $100 (from memory), so you might want to look at that as well. however common problem of ignition modules is stalling when hot and not starting until it cools back down again - i don't think it's your module.

[greenfoam]

I see you have replaced some stuff before but I would be looking at those same things again. You can get a ECU from the wreckers for no more than 50 bucks and probably less than that just to rule that out. Sounds like your spark is totally falling off or the fuel pump is stopping. Might even pay to wire up a light to the fuel pump to keep an eye on it's power

[bloodyricho]

agree with foamy its the dang dang it ECU some shity resistor is on it way out worked on a vs 5ltr ute with same problem i said from start ecu no one believes ya including the customer cause he's busy listening to the boss dribble poo. it was the ECU i stuck one in late on a friday against bosses orders handed him the keys and told him to find another cow to milk or i would quit. damn it if that ute hasn't had anymore work done 2 it for ages

[jon_vs]

OK - Thanks heaps for all your ideas and comments. Here is an update. If I drive the car for any length of time more than say 40 mins, then it is likely to stop after that period of time. For example, I went down to Wollongong (from Sydney) last Saturday. The car performed faultlessly all the way there. However on the return journey (some 6 hours later) it stopped after 10 mins into the journey. After it started again (a little more difficult) it stopped about 5 mins later. After I started it again (almost immediate), it ran faultlessly all the way back home. After it fails I can always hear the fuel pump priming the rail so I guess that rules the fuel pump out as the problem. To me it comes down to either the HES, the ICU or the ECU as the source of the problem.

Does anyone know of a “test” that would identify which of the 3 units is at fault? Is the only alternative to replace all 3 units? If so it seems a bit of a waste. Is there a “swap out service” available to replace each unit in turn, to identify which is at fault and then you purchase an exchange unit for the faulty unit? Any ideas?? All comments are greatly appreciated.

Jon