C20LET Keeps Revving!

[rusty]

Started the turbo this morning and it keeps revving at about 3000 revs. Fault light came on and i got codes 31, 94 and 95.

I have looked at the guide so i know what the codes mean but how do i fix it?

Thanks

[AnThoNYnOvA]

wat are the faults then?

[rusty]

31 Engine Crank Sensor No signal
94 Hall Effect Switch High Voltage
95 Hot Start Valve Low Voltage


UPDATE

Just took the car out for a drive (after leaving the battery disconnected to reset the ECU) and now when you start it it runs between 3000 and 4000 for about 10-20 seconds
Then it idles fine but when driving it misfires and runs really lumpy. Boost is still fine and now i have no ecu light on.

HELP

[PAG]

could be the idel valve control unit! they are common they dry up inside if so can take it off from under the car its under the inlet manifold think 3 pipes are connected or 2 think 3 thou and a plug on the top give it a good clean with some carb cleaner and then some lube!


you should not of reset the falts that way. should of pluged it to a computer eg auto diagnostics. then reset them via that!


or it could be that you have a air leak after the air flow meter check the pipes! or airflow is getting tired.


right iam going to bed! hope this makes sense as iam half asleep!

[Ste_Nova]

battery off is the best way to reset... cause it also clears the learnt map

[rusty]

how large are the pipes for the idle control valve? cos the only thing i could find is under the inlet manifold near the gearbox. It has two pipes coming out (about the same diameter as the washer bottle hose) but one of them is blocked.

Any pics?

[rusty]

ok just unplugged the throttle pot and it idles normally now. So i'm guessing that it is fubared. But now i get error codes 21 and 31.

21 is throttle pot voltage high - but i'd expect that cos it's unplugged

31 is inductive pulse pickup (crank sensor) - no signal.

Do these usually fuck up or could something else be causing it? Anyway to test it?

[david dixon]

I have heard of the crank sensor's going off before, that will probably be your problem, If its not working your ecu wont be getting a true reading to what the crank position is. hense the miss fire.
I would just try someone elses sensor and that'll show if its that.

[rusty]

but from what i can see the crank sensor is half hidden behind the front engine mount. is this right?

[rusty]

anyone?

[david dixon]

This is true, It depends on what mount you've used sometimes it could be taken off without removing the mount but it sounds like you might have to support the engine on something and take off the mount then take out the sensor!

[Jules]

My GSi (Pretty standard engine) has started to do a similar sort of thing - I was driving along recently and when I came off throttle to stop at a junction the revs were at about 2000rpm - I blipped the throttle and it dropped back down to it's usual 900 rpm - I just assumed the throttle cable was a bit out of adjustment and had got stuck.
However today whilst driving the missus to work I was waiting in a queue of traffic at idle (again 900 rpm) when the revs started to rise, again I blipped the throttle and it returned back down, it then went ton to do the same thing another 10 or so times onmy return journey.
The ECU light hasn't come on once so I'm not sure if I can read it for faults as it's not reporting any it would seem. This also rules out the throttle cable theroy as it does it from idle with no help from the accelerator pedel at all.

Any ideas?

P.S. Sorry to kind of steal this post but it is a very similar problem.
:wink:

[david dixon]

On a gte/gsi engine it could be 1 of a few things.
1: Your timing could be advanced a little to far. causes them to rev up!
2: The air/fuel ratio could be running to lean, this also causes them to rev up.
3: idle air valve on the side of inlet manifold could be worn.
4: Could have a sticky throttle switch, Hense when you blip it, it stops!

[robb]

The sensor on the side of the engine on my GSi, motronic 1.3 system is useless. I have not got one in there and mine idles fine. That is the one near a plug for two vacuum pipes on the right hand side halfway down inlet pipes.