driving / random stall / sumtimes just cranks when starting

2 things jump to mind.

Fuel pump. If you cant hear it prime with the ignition to the 'on' possi. (but that does not explain the random cut out while on the road)

Or the CAS.

Then it also could be the ECU on the blink or a bad earth somewhere.

 

The ECU will keep any fault codes till cleared so that should give you a clue. Does sound like the CAS.

 

The ECU only stores a fault code if the 'fault state' is for 30 seconds. That maybe a crock of poo too, but I think I read somewhere if the condition (fault) is for this amount of time a code will be recorded.

My wagon started to cut out when doing 100 on the expressway just a quick miss to start with then finally it started cutting out 'dead' - needing to pull over and it would fire up no problems. That issue was a faulty ECU.

 

Yup - read a different book and you'll get a different answer.
Gregorys says: "When the ECU detects a fault, it is retained in the ECU memory as a fault code until the engine has been started 50 times or until the codes are cleared"
I seem to remember reading in another manual that it was 20 times.

 

Ummm - the time the fault exists for - as in how long the fault occurs for so if the engine is lean for 30 seconds of more the ECU stores this as a code 13 or what ever the code is.

So some times when the fault is for just a flash the ECU does not retain this info.

Thats what I was on about.

 

I agree, what you say is logical - I was stressing more about one source says this and another source says something different. I don't doubt that you are correct, its just that sometimes you get different answers which is to be expected on any open forum. - Like:

HOLDEN COMMODORE VR 5.0L V8 (VU Eng.) 1993-95 Engine Management System


Fault Codes
The PCM incorporates a Self Diagnostic Function which detects System Malfunctions.

It indicates the presence of a Fault via the Malfunction Indicator Light (MIL).
This is located in the Instrument Cluster.

System Malfunctions fall into Two Categories.

1. Hard Faults

Indicated by the MIL being illuminated whenever the Engine is running.

2. Intermittent Faults.

Cause the MIL to be illuminated while the Fault is present.

The MIL will go out approximately Ten Seconds after the Fault disappears.

Faults of Either Type will cause a Fault Code to be stored in Memory.

 

Havent heard that one before. On one hand it could be true - you dont want the error log filling with codes galore just because a signal was a little funny getting started. On the other hand, intermittent faults could be missed, which is half the reason for fault codes.

Acutally thinking about the CAS. When they go, the car stalls almost instantly, yet a fault is still logged almost all of the time. Theres no way the car could run for 30 seconds without that CAS signal - so I dont really believe it entirely.

Maybe there is a bit of truth to it, as in some faults must remain for > 30 seconds, which is preprogrammed into the ECU.

 

ok sounds real dumb but ive had the problem before
just check that the terminals are on tight
lol

 

Since it only takes about 20 seconds to stick a piece of wire between pins 5 and 6 in the big plug under the fuse box panel and turn the ignition on it would probly be worth checking , just in case there is a fault code ..
Problem sounds like what happened to me a few weeks ago when my ignition module died on the highway at 100 k's. Engine stopped instantly. I pulled over andit started again a minute later but died again 5 minutes later. The part cost $275.

 

had this problem in my old VR...
got the CAS and harmonic balancer replaced (harmonic balancer needed replacing so i figured id do it while i was gettin the CAS done)

worked fine for about a week then happened again... replaced DFI module and she was all good.

CAS and harmonic balancer cost me $290 installed (i think) and the DFI i did myself cost me $220 from auto one... you can get them cheaper tho, i just happened to have a voucher for auto one... coventrys do them cheaper.

 

Does sound like a CAS/spark problem but then again could be a fuel issue...