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Increasingly worrying and dangerous electrical fault

Posted: Thu May 05, 2016 2:39 pm
by portaccio
Hi,

I have a recurring fault that is getting more frequent and as a result more dangerous. I think it's electrical and may have something to do with the central locking system.

As I'm driving along the engine starts to misfire and lose power.
The engine management light and the central locking lights flicker on and of like crazy.
When I take my foot off the accelerator the car idles with no issues but if I apply the accelerator the misfiring and light show starts again until I grind to a halt.
The car will start again after a few minutes. The longer I leave it the longer it seems to be until the next episode but it usually happens 4 or 5 times in a row over 5 or so miles. Eventually the fault clears and will not occur during that journey.

My mechanic has used his diagnostic tester and found no fault and he hasn't been able to get the fault to occur (sods law) so does not know what to do.
It only usually happened on long motorway trips which are rare for me so wasn't really an issue but recently it is almost daily and it's only a matter of time before it happen in a dangerous situation. My mechanic says we have to wait for it to break before we can fix it but that sound s like bullshit to me.

Has anyone come across this fault before?

I have uploaded a video of the fault in progress on YouTube.


Any and all advice much appreciated.

Regards
Tom
https://www.youtube.com/watch?v=tn2d1UN ... e=youtu.be

Re: Increasingly worrying and dangerous electrical fault

Posted: Thu May 05, 2016 4:37 pm
by Jazza
I had a similar problem with a Fiat Cinquecento about 8 years ago.

It turned out to be the ECU, but I don't what caused it to go wrong in the fist place.

Cheers, Jay

Re: Increasingly worrying and dangerous electrical fault

Posted: Thu May 05, 2016 5:01 pm
by zook123
Don't quote me on this, but try another key, I do remember reading this on another forum, turned out to be the immobilizer?

Re: Increasingly worrying and dangerous electrical fault

Posted: Thu May 05, 2016 5:48 pm
by portaccio
Cheers,
wouldn't a dodgy ECU show p on a diagnostic test?
I thought it might be something to do with the immobiliser. But what???
It gives us something to try.

Re: Increasingly worrying and dangerous electrical fault

Posted: Thu May 05, 2016 7:28 pm
by Darrell
This sign is for the immobilizer on so trying another key (if you have a spare) may possibly work. I'm afraid the mechanic is largely correct, finding an intermittent fault is very hard to find if it didn't store a code. Once it screws up properly then you have something to fix. Hopefully Rhinoman will read this post, if anybody has a clue where to start, it will be him :thumbup: .

Re: Increasingly worrying and dangerous electrical fault

Posted: Fri May 06, 2016 9:14 am
by zook123
My Corsa currently has an ECU fault, no codes showing, but looses power when you hit 4k!

Re: Increasingly worrying and dangerous electrical fault

Posted: Sat May 07, 2016 2:39 pm
by Rhinoman
This is usually a cam or crank sensor fault. The immobiliser is only activated at key on - the light comes on when the ECU believes that the engine is not running.

Re: Increasingly worrying and dangerous electrical fault

Posted: Tue May 10, 2016 12:01 pm
by portaccio
Hi, thanks for the advice. I've just limped miles to my mechanic with the fault in full swing only for the fault to clear as he comes out of his garage. He took it out for a 20 minute drive and nothing. This is crazy.
maybe I'll just get the cam and crank shaft sensors replace and look into getting a new key. Maybe that'll fix it???
Cheers again.
Tom

Re: Increasingly worrying and dangerous electrical fault

Posted: Tue May 10, 2016 12:06 pm
by zook123
Have you got a spare key for it?

Re: Increasingly worrying and dangerous electrical fault

Posted: Sat May 21, 2016 7:33 pm
by portaccio
Rhinoman wrote:This is usually a cam or crank sensor fault. The immobiliser is only activated at key on - the light comes on when the ECU believes that the engine is not running.
Bang on. Started with the cheapest fix first. Got a new crank sensor and not had any trouble since.

Thanks very much

Tom