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MG MGF Technical - Revs far too high

Help

I've just got my car back after an HGF and have noticed that it's revs are shooting up to around 3000 when I put my foot on the clutch to change gear or stop. It also seems to be doing it when I'm driving along. I can take my foot off the accelerator completely and the car is just driven along by mega high revs.

Could anyone tell me what this problem might be. I've been without the car for almost 2 months already. I am not amused.

Cheers

Sally
Sally

Sounds like a sticky throttle cable - if you leave it do the revs fall after a couple of seconds?
Will Munns

No, the revs just sit there until a flick the accelerator pedal. It then either climbs a bit more then drops or drops back to normal.
Sally

check throttle position sensor, mine was loose and was causing very similar symptoms.

clicked into place and problem was resolved.

hth.

Paul.
paul weatherill

check that the pedal spring is on properly, and the cable is properly located at the throttle body.

Then check the TPS (on opposite side of throttlebody to cable cam) as paul said (but I don't know why this might have been touched as part of the service)

Then check that the clip holding the airfilter hose to the throttlebody is not too tight

Then reset the TPS info by switching on the ignition (red lights no engine running) fully press the accelerator five times, then switch off.

HTH
Will
Will Munns

I had this sort of thing this morning. The car only just started as the battery is once again a bit flat. and on the way to work the revs would not go below 2000 revs. even whilst waiting at he lights. I thought hmmm this feels like a ECU problem!! No end of revving made any difference. I thought I bet when I switch it off and restart just like rebooting a wonky PC it will behave normally again...and I guess what? ...I was right!

got to work stopped the car, restarted it and Bingo perfection...dodgy electrics!!!

You just have to know how to deal with this stuff, the ancient art of motor maintenance hasnt moved on much , it's just got infected by Bill Gates!!

So Sally here's a clue.
Take it back to the garage and have a go at them if the symptoms persist!
Neil

Please try this as I know at least myself and Dieter had this problem and the cure can be quite simple. Simply make sure all the connections on the mems are secure and making good contact. You could also check the various plugs around the IVAC,TPS and indeed the throttle body itself.
S Laithwaite

Lastly, check the throttle cable is seated correctly in the throttle cam, if it is loose then it can jump out of it's groove/channel and cause there to be tension on the throttle cam when the pedal is at rest.

SF
Scarlet Fever

Just a thought guys, those are also the signs of the "old" throttle body problem.... as you've had the head off, there would be more than a fair chance of an overtightened clip distorting the plastic body - if, of course, you still have one... good opportunity to obtain an alloy 52mm TB I'd have thought...
Mike

There's of course no easy solution. :(

You need to analyse and put down the problem to either electrical or mechanical problems.

Check all above recommendations, but be patient and don't do everything at once. Do step by step and try whether it cured or not.

Looks like a problem with the control of the IACV stepper motor.
But the question is, why does it fail. The reason could be each and everything from MEMS input (sensors, cables) or the output (IACV).
btw. the easiest but expensive test for input failures is a Testbook session at your dealer (.. may be FOC after complaining about their earlier repair works). They will not be able to analyse output failures or mechanical problems though.

I'm sorry, haven't updated the affiliated webside about my troubles with high idle.
This all ended up with not starting engine. (See Stevens hint) and disconnecting / re-connecting the ECU did cure the problem. Main reason was a missing cable tie fixture of the ECU harness just in front of the connector.
http://www.mgfcar.de/starter/start.htm

HTH
Dieter
Dieter K.

Sally,
Take it back to the people who did the head gasket, sounds like it's their problem , could be throttle cable ,distorted throttle body, sensor or even ecu, let them sort it as if it was not doing this before the head gasket then they have done something wrong,
Robert
R J Hemphill

Is the battery 100%? After my F was off the road for a couple of months getting repaired it came back with a flat battery that never really recovered, i.e. woun't hold a full charge. Started getting the revs problem and checked all the usual. Eventually got a new battery and the problem went away.
John Pickup

This thread was discussed between 07/05/2004 and 09/05/2004

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