172 Rev's on its own?

[davewilliams]

Hi Guys, I havent been on here for ages now mainly because iv had no problems with my clio due to the engine not being in the car. However iv just had the cambelt and a couple of things done to it and put the engine back in last night. We fired it up and for some reason it revs straight up to about 3000rpm, iv got no response on the throttle and for some reason when i put my foot on the brake pedal the revs drop back down. No idea whats causing it.

Any ideas?
Cheers, Dave.

 

[Ian_s]

You havnt plugged the throttle back in...

 

[davewilliams]

Throttle is definately plugged in, iv checked the plug in the back of the throttle bodie and in the throttle potentiometer and they seem all ok. it just seems weird that the brake stops it from reving?

 

[bmh.01]

Throttle pedal isn't plugged in or isn't being seen by the ecu. This is standard behaviour with the pedal disconnected.

Fault light(s) on as well i'm guessing?

 

[davewilliams]

Got that pesky limp mode light on, the box with the zig zag line goin through it.

 

[dt2703]

Check the electrical connector under the air intake elbow.

 

[bmh.01]

Check the electrical connector under the air intake elbow.

Won't be the body unplugged, car will idle normally(ish) with the body unplugged. Certainly won't do 3krpm anyway.

Got that pesky limp mode light on, the box with the zig zag line goin through it.

Yep, because the ECU can't see the throttle pedal.

 

[dt2703]

I accidently left this connector off when I changed the plugs the other day, the throttle peddle didn't work and the car gradually increased in revs on it's own. I switched it off when it got to 2krpm, but it sounded like it would have climbed to 3... I also had the dash light on.

 

[bmh.01]

Still, in this case its deffinetly the pedal. Its got throttle control or it wouldn't be able to drop the revs to idle speed.

 

[dt2703]

Fair point

 

[davewilliams]

Just out of interest, if you unplug the sensor on the right hand side of the inlet manifold (the grey 1) is that ment to change anything? for some reason i think i was tinkering with it last year and unplugged that sensor and it reved up but i cant remember if i had any control on the throttle or if pressing the brake pedal made a difference?

 

[MicKPM]

Not really, its the air temp sensor

 

[bmh.01]

Just out of interest, if you unplug the sensor on the right hand side of the inlet manifold (the grey 1) is that ment to change anything? for some reason i think i was tinkering with it last year and unplugged that sensor and it reved up but i cant remember if i had any control on the throttle or if pressing the brake pedal made a difference?

Electrically unplug or remove it from the manifold?

 

[davewilliams]

I think i just unplugged it but at the moment it doesnt change anything if i unplug it or pull the sensor out of the inlet manifold.