Mk3 Cavalier Owners Club | Vauxhall Cavalier Dot Com

Oddly I was helping someone with a near identical problem yesterday, c20se that would not start. Plugs were sparking, turning over ok. Engine had been out for work on it, and loom bodged in places, and other nice red herrings.

Turned out to be the fuel lines were on the wrong way round, and then all 4 injectors were blocked as the engine had been sitting for so long. We clamped the fuel return to get pressure as the regulator looked ropey, and I manually pulsed the injectors, after some seconds a little fuel slowly started to trickle from the injector, then a tiny spray to the side. Put it back together and it was trying to fire on that one cylinder. Told them to sort the injectos and get a new fuel reg.

Got ECU out and got it open. There is a small bit of corrosion on the top of the case but inside looks fine. Still scratching my head....

That looks freakishly familiar after opening up the ECU too yesterday since I though it wasn't firing the injectors.

This is interesting, I haven't paper clip tested since it actually stopped working but I've just tried it and the eml is solid and not flashing. Any ideas why?

The EML should be solid if there is a current fault.
Or if the ignition is on but the engine is not running.

A flashing EML would indicate that the transponder key chip is not programmed to the immobiliser and / or ECU.

If the EML goes off immediately upon starting, then there are no historic or current faults.

If the EML goes off a few seconds after the engine starts, then there is a historic fault stored.

So at the moment I have no way of finding the fault because it won't flash me a code....

I am going to ask a daft question, so I apologise up front.

Are you doing the paper-clip test with ignition on, but engine not running?

And have you disconnected the ALDL plug, shorting pins A and B of the diagnostic socket together.?

If the engine is running, the eml will flash once every second.
It will not flash out a code sequence.

If the ALDL socket is still plugged into the car, it will do as I described in the previous post.

I thought they still flashed up the codes when the engine is running.

I'm doing it with ignition on but engine not running (because it doesn't start)

I'm doing it by unplugging ALDL plug and bridging A+B

I thought you would have done, but sometimes it is good to stop, and go back to basics.

Okay solid on with the ALDL plug removed and ignition on looks like an ECU fault.

I cannot see it being anything else.
Unless you have a damaged loom cable.

But I am sure you have checked the loom for damage too. (Nipped by careless fitters when refitting the gear-box).

Whenever an ECU either refuses to communicate or responds in a way that does not make sense, chances are that it is faulty or the loom is damaged.

vexorg wrote: ↑Sun Oct 24, 2021 1:01 pm I thought they still flashed up the codes when the engine is running.

I tried this years ago on my original C18NZ and later with the retro-fit C20NE.
In both cases, it just flashed on and off every second or so (no flash codes) with the engine running.

Ok, maybe we're getting close to the root of the problem
I'm pretty sure the wiring looked alright but I'm going to double-double-check. If all is good I'll try a replacement ECU

Thanks for everyone's help on this, turns out it was the ECU. Got hold of a newly refurbished ECU and all seems well again.
Hopefully that's the end of the engine niggles so I can spend some time on the scruffy interior

Glad it is finally sorted.
Back to enjoying your car again

Good now get driving.