First id like to state iv changed the battery the distributor cap is fine the plugs are new the leads are new everything is plugged in securly. I am the only one who works on this car and have had it a few years so i know it pretty well and this is the first time iv come across this behavior and need to take into account i have flashed my ecu about 40-50 times in the last 2 months

I flashed my car yesterday then went to start it and it just cranked over without firing, i thought it might be the key ring as iv had issues with that in the past but seemed fine after 15 mins or so it started

After driving around for a while i went to turn around to go home and it stalled and same thing a while later it started, after starting it again i was driving home and the engine electrics cut out and car lost power and after 5 seconds or so it kicked back in. When i got home as soon as i turned the car off i tried to start it and it wouldn't go, after a while it started and was as if the AFM was unplugged (Rough as idle, dog rich running, wouldn't rev) plus unplugging the AFM made no difference. I tried my spare AFM but no difference, after cracking the S**TS with it i left it till today i went to start it and first it started (no better) then i turned it off and went to start it the second time and now it cranks over and ever few seconds it fires once on one cylinder but no go at all!

Does this sound like i have fried the ecu or does anyone have and suggestions on what the issue may be ?

Before you do anything, make sure all your vacuum lines are plugged in and all engine bay wiring harness plugs are plugged in properly. If all that fails then it could be your distributor, I had that same problem a while age and had just reset the ECU so thought it could have been the ECU but it turned out to be the distributor its self. See if you can get a second hand one from the wreckers and hopefully that will solve your problem.


Cheers Luke

Thanks for the reply just happens i have a stripped engine here with a complete distributor so ill change that and see how i go, any more suggestions are highly appreciated!

Changed the dizzy and no difference!

It starts sometimes but runs really really rough, most of the time it wont start at all.

My concern about the ecu is because the issue started after a reflash

Changed the dizzy and no difference!

It starts sometimes but runs really really rough, most of the time it wont start at all.

My concern about the ecu is because the issue started after a reflash

Can you still flash the ecu.? Maybe a bad load, do you have the factory default to load bad into the ECU and see what happens. How are the cam and crank sensors? Any damage to the looms etc.

fact is car worked fine...you reflashed it and it's broken.


check everything you disturbed along the way...you probably havent reconnected something properly.

I'll bet then ECu is fine...it's something you have overlooked.

I am able to reflash the ecu and i currently have the factory tune flashed

After more playing around i have found there to be no voltage at the TPS ? all other sensors MAF, Idle Control, CAS Etc have voltage. The wiring diagram shows the TPS gets it voltage straight from the ecu and that wire doesnt supply any other sensors and i tested the wire in a few places and theres no voltage anywhere.

All i do when i reflash is plug the laptop in to the usb cable in my car and reflash, the OBDII conector is always plugged in and the reflash conector is always plugged so the only thing that changed is the settings in the ecu

check your fuses...wiggle all the plugs..

In the manual it doesnt show it going threw the fuse box but ill have poke around anyway!

How many times have you reflashed your ECU? The EPROM chip inside the box is only good for a certain number of flashes - how many I have no idea - before a flash becomes error prone. At a guess getting another ECU and putting the factory tune on it will tell you one way or another that the current ECU is at fault.

First step, determine whether its the spark being erratic, or whether it's the injector pulse when it plays up.

ECU arrived today ( I wanted a spare anyway ) ill flash the original ROM i got off my ecu to this new one so in theory everything should be the same such as the imob code

Okay the ecu is not dead after more digging a have found the injectors arnt firing

Now today my brain clicked and i remembered my car use to be on gas (sprintgas) i have taken it out because it was a restriction at best, it seems like the gas ecu acts as an interceptor to the injectors so im guessing the gas ecu has switched the injectors off as the injectors have power but dont fire

the question is does anyone now how i can remove the gas ecu and re connect the injector wires, i have a wiring diagram showing the injector wires from the ecu but i have no idea on the wires coming from the gas ecu

Okay the ecu is not dead after more digging a have found the injectors arnt firing

Now today my brain clicked and i remembered my car use to be on gas (sprintgas) i have taken it out because it was a restriction at best, it seems like the gas ecu acts as an interceptor to the injectors so im guessing the gas ecu has switched the injectors off as the injectors have power but dont fire

the question is does anyone now how i can remove the gas ecu and re connect the injector wires, i have a wiring diagram showing the injector wires from the ecu but i have no idea on the wires coming from the gas ecu

I've never had gas but is'nt there normallly a switch which lets you select gas or petrol?

Okay the ecu is not dead after more digging a have found the injectors arnt firing

Now today my brain clicked and i remembered my car use to be on gas (sprintgas) i have taken it out because it was a restriction at best, it seems like the gas ecu acts as an interceptor to the injectors so im guessing the gas ecu has switched the injectors off as the injectors have power but dont fire

the question is does anyone now how i can remove the gas ecu and re connect the injector wires, i have a wiring diagram showing the injector wires from the ecu but i have no idea on the wires coming from the gas ecu



mate...take it to an LPG fitter cause you shouldn't have played with it to start with....you want a burnt out shell?

So have you just removed the mixer or removed the tank and everything else. Removing this stuff yourself is rather silly to be honest unless you are certified in Gas which if you dont know how to remove the wiring then I would say you are not

The best bet, get another injector loom then you can just remove the other part of the harness and gas ecu. This is not hard to do as all they do is loop a wire through the gas ecu loom, ie cut, and then run the various sensors etc in series. Generally is TPS, CAS and injectors

Strange that it's suddenly happened though, but as Mal said.. the ecu is fitted in series, so its a matter of cut & re-joining existing wires. Definitely check for old fuses that may have blown, around the engine bay where the converter was previously. Check for aftermarket fuses fitted near the battery + terminal. Check under the dash and close to the LPG computer.
Also, does the car definitely have spark too? Need to know, otherwise you'll be chasing your tail around.

Double post... apollogies :P

I know it was sily taking it out myself but its done now, the only thing i left was the ecu everything else is gone

I took the gas ecu out last night and rejoined the wires there was two that where cut fed into the gas ecu and then fed into the loom so i joined them, there was also three more that where just tapped into the loom so i removed them and taped up where it was tapped. Still the injectors arnt firing and i have spark, like i said in my previous post there is power going to them so thats not the issue

Fault codes, next step. Possible immobiliser fault.
Let me know when you get a code readout.

Its not throwing any codes unfornunatly, that would make things so much easyer

Does the immobiliser cut injection or spark ? is there anything else that cuts injection ?

Hmm afaik, not a whole lot. Most other things, such as ECM relay cuts injector positive, but since they are negatively triggered that doesn't help much - as you said they do have 12v atm, correct? See if there's pulse at the ECU. Backprobe one of the injector wires, if there is then you'll have to trace things further down the line.. if not, then it's something a tad more sinister unfortunately.

Also while you're backprobing - make sure you have good signal from the CAS and the TDC sensor at the ecu. Doesn't hurt to cover the essentials.

Yeah the injectors all have 12v, i knock off in half hour so ill go probe one of the injector wires coming out of the ecu and see if it pulses while cranking.

My battery died today from cranking it so much so ill take a new one home with me just so it doesnt add to the problem

Also what are peoples thoughts on relocating the battery to the boot? (this is what i done well over 6 months ago to make room for intercooler pipes)

Okay there is pulse from the ecu to the injectors so the issue must lie between.

With the ignition off im getting earth with it on or cranking im getting none at the injectors

Yeah the injectors all have 12v, i knock off in half hour so ill go probe one of the injector wires coming out of the ecu and see if it pulses while cranking.

My battery died today from cranking it so much so ill take a new one home with me just so it doesnt add to the problem

Also what are peoples thoughts on relocating the battery to the boot? (this is what i done well over 6 months ago to make room for intercooler pipes)

Long way for the current to flow. latest commodore has it there, have not heard anything good about it and I have heard stories of gases / odours building up but it's heresay.

They need to be adequately vented to the atmosphere outside of the boot. Doing this on a car which was not originally designed to have a rear battery might be asking for trouble, but on the other hand many people have done so successfully. Check your ECU reference voltage too! I know of a few cars which have had problems starting, due to aged batteries (astras, rodeos especially, etc..). They'd crank over fine! You'd swear there was nothing wrong with the battery.. but there just isn't enough of a reference voltage to the ecu to function correctly. If you think you definitely have pulse at the ecu, its time to start tracing the wiring for continuity with a multimeter. Start at the injector side and trace backwards until you find no continuity. If you find no breaks, start at ecu end and do the same.
Good luck. I know how irritating these sorts of problems can be.

There are 4 factors needed, fuel, spark, injector pulse and compression

If all of these are there and in the right place engine will run

You state that there is injector pulse, there is 12v at injector. If there is spark and all this is happening at the correct time, aside from a dead engine, you will get bang.

Check your spark is happening when it should be, remember if dist or CAS is dicked, you will have no injector pulse