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MG MGF Technical - throttle keeps pumping..

Hiya. Recently had annual service including 4 new spark plugs, ignition coil and new battery. Now find the car is fine when cold as automatic choke keeps engine revving OK, but as soon as engine warm find occasionally (some days fine, others continual problem..) that when foot not on throttle the engine revs then almost stalls so revs again (and repeats this continually...). Garage couldn't find a fault as they just let engine ticking over and it only does it after car is moving ie been much higher revs. Any ideas, As when it pumps it eventually stalls and is dangerous. ?


sit in car turn on ignition to second position push throttle pedal up and down seven times (this resets the throttle sensor}should be ok after that i have to this about three times a year
tg hardwick

If that doesn't work, take it to your Land Rover main dealer and they'll re-set it on their machine. Unfortunatly, it's a main dealer only job as other diagnostic machines will NOT 'talk' to the MG / Land Rover one...

M T Boldry

thanks for these. Tried the pumping the throttle 7 times, which I thought cured the problem, though a few times when i slowed down at junctions the revs suddenly shot up. However after a while it settled OK for rest of of my "test" journey. Not sure what to do next. I understand this problem is called throttle "hunting".

Hiya again... still got the hunting problem once the car has reached normal temperature. The garage replaced one ignition coil as it wasn't giving enough V. Still doing it, though... Any other ideas as to the problem before I sell it and buy a Tata.... (joking...)

anything to do with the throttle position sensor itself (faulty?) Pumping the throttle 7 times didn't do anything. Should the fault show up on computer diagnostic machine? Sorry lots of questions. Maybe all will be well in the spring when it's warmer?

Hi Janine,
hate to say this but did you see the old spark plugs?
Did they replace with platinum plugs? Maybe they didn't replace them at all and said they did. Did the car run like this before the service as it seems strange and quite bad now (stalling). You say they only changed spark plugs, battery and ignition coil plus usual service like oil change and inspections. Also did they replace spark plug leads? I'd be getting the garage to find and fix the problem. They stuffed it they fix it. Yes as Mark says the fault should definitely show up on a diagnostic machine.
Just had a thought Janine...Maybe your MGF just wants to stay in the warmth of your garage and it's showing you this by stalling. Just a tad cold in the UK at present I hear. Also cuddle it in a duvet till summer. Cheers Sue
Sue Wilson

Thanks for this Sue. The garage say they will fix it at no cost, but just don't seem to be able to do it! The car was fine before the service. I will put your suggestions to them. The car runs fine so spark plugs all work, but maybe not the right ones. Battery is Ok as started car 1st time for 3 weeks after -10 degrees C for a month without any problem (for those in New South Wales, -10C is below 20 degrees C. PS any chance my car and i can move to warmer climate!)

Hi, finally diagnosed problem - I hope!- crankshaft sensor. The car was running irregularly on idling as well as hunting and stalling. Fitted me a free set of platinum spark plugs. Will run car a few weeks before jumping for joy......

bestest, janine

oops.. meant camshaft sensor, not crankshaft sensor. It's been a busy day....

Hi Janine,
Check this out on youtube
camshaft sensor not re-connected when changing plugs?
Sue Wilson

This thread was discussed between 21/11/2010 and 21/01/2011

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