Corsa C 1.2 16V - Drive by wire hrottle problem

Honest John Back Room » Technical matters
View Threaded
Sat 7 Jun 2014 09:43
Corsa C 1.2 16V - Drive by wire hrottle problem - bootzey
My daughters Car has a problem with its DRW. Turn the ignition on and the throttle constantly try to set itself, the EML and Spanner lights flick on and off simultaneously with the throttle body moving and sometime the fuel pump works to. There's no codes stored other than an immobiliser fault code. When it settles and I press on the accelerator pedal gently the same thing starts to happen...the more I press on the pedal the more frequently it happens until I reach full throttle when the throttle body just goes closed to fully open constantly.
When the engine is running, ticking over nicely, I do the same with the pedal and when the revs build up to roughly 2500ish the engine stumbles (when driving the speedo drops to zero) but recovers and goes higher. When I press down quickly on the pedal, the engine stumbles, warning lights come on and a loud sucking noise can be heard from the air filter box...then when it recovers the warning lights go out.
The car worked fine a couple of days ago, but is very noisy when hot, which is why I was able to get the 1612 fault code. Then I changed the oil and it's as described above.
Just can't figure it out, any ideas welcome please.
Thanks
Reply | Report as offensive | Link
Sat 7 Jun 2014 10:53
Corsa C 1.2 16V - Drive by wire hrottle problem - elekie&a/c doctor

Flashing warning lights and an erratic throttle body operation are classic symptoms of a failing engine control module.There are a couple of things you could try first.Make sure that the earth lead on the ecu body is clean and tight.Try running an additional lead from this earth point direct to the battery earth terminal.Also ,with ignition off,disconnect the throttle body ,then ignition on,to see if this stabilises the dash warning lights.hth

Reply | Report as offensive | Link
Sat 7 Jun 2014 12:22
Corsa C 1.2 16V - Drive by wire hrottle problem - bootzey

Thanks for your thought and reply.

Totally understand but I'm trying desperately to avoid changing the ecu...though I have been offered one for 25 quid but then there's the rip off expense of reprogramming and new keys...they're deliberately not made to be plug n play.

I just can't figure out why the car changed one day (I did remove the ecu connections and blow through them) and was Ok then reverted back to playing up after an oil change...though some oil spilled when I was changing the oil filter...any thoughts please?

Regarding the earthing, I have played about with this and it didn't make any difference though I didn't try it direct to the battery so will try when the rain stops.

It seems like the Ecu doesn't know when the engine is running or not. Is there a sensor among the multitude on it that tells the ecu when the car is running...like the MAF only operates when the engines running?

Reply | Report as offensive | Link
Sat 7 Jun 2014 12:50
Corsa C 1.2 16V - Drive by wire hrottle problem - bootzey

Right might be getting somewhere now!

Went out to the car turned the ignition on and it was fine...i.e. No problems, no throttle having a fit, no flashing lights. I even managed to do the pedal trick and got one code...1612 again which is immobiliser. Left the ignition on to see if it got hot and played up, didn't start the engine though and got no problem.

However...when I opened the bonnet...there was water all over the battery and the box next to it which I think has some relays in it. Can see these two things through the scuttle.

So this narrows it a bit.

Could it be water is making a good connection somewhere?

Or...could it be the ecu temperature sender playing up as the engine gets hot?

Or could it be the ecu playing up as it receives heat from the engine because of its stupid positioning? However this wasn't the case yesterday.

There's only two things different from yesterday....rain ingress and temperature.

Thanks

Reply | Report as offensive | Link
Sat 7 Jun 2014 14:49
Corsa C 1.2 16V - Drive by wire hrottle problem - elekie&a/c doctor

Nothing to do with water..Temperature very possibly,as the pins to the ecu and connector expand and contract.,and as you say,the ecu is bolted to the engine.The box next to the battery does not contain the fuel injection relays.

Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide