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MG MGF Technical - sticking throttle?

hi everyone ,first time on.

a couple of months ago i thought my 96 f had succumbed to the sticking throttle problem that seems to dog early cars.idle speed was staying between 1500 - 2000 revs.this gave me the excuse i needed to buy the 52mm alloy throttle body which i fitted this week.alas the problem is still there.also now i find the car hesitates for a second when the accelerator is pushed hard. anyone have any ideas. paul
p rachell

Have you reset the TPS?
The problem probebly wasn't the throttle at all, but the temp sensor - does the fan run all the time?
Will Munns

Hi Paul,

Is the idle always high or do you get spells where it behaves normally?
Mike Hankin

Hi Will & Mike,

Thanks for your replies. There are spells when the engine idles and revs normally. Have reset the stepper motor and there was a slight improvement in idle. Fan doesn't run all the time.

Thanks,
Paul
p rachell

Paul,

If your car is a 1.8MPi of 1996 vintage, the problems you are describing are probably two separate issues.

1. The fast idle

The way you're describing the problem makes it sound like the classic engine management water temperature failure. When it fails, it fools the ECU into thinking that the engine is still cold, when in fact it is perfectly warm! Various things you can try to solve it - more information here: http://www.mgf.ultimatemg.com/group2/common_problems/hgf_pages/related_problems_overheating.htm

2. Stuttering/hesitation

This sounds as though it could be related to degeneration of the rotor arm/ distributor cap. Replacement is simple and usually resolves the problem - see http://www.mgf.ultimatemg.com/group2/common_problems/distributor/stuttering.htm

Good luck :o)
Rob Bell

Or possibly the 'problem' I've had for a year or so now, which is an occasional bad connection/fracture in the wiring to the throttle body. Long shot I know, but next time you get the high idle reach in and nudge/wiggle the wires coming away from the TB, about an inch back from the plug - works for me...

Is the hesitation on hard acceleration evident when the idle has been behaving itself, or just when it's high? And do you get a jerky overrun sometimes? If so, welcome to my world ;o)

Mike Hankin

Rob
thanks for your suggestions. i will check them out when i get time.
p rachell

Mike
pulled and prodded the wires,no joy.
the hesitation only occurs when the idle is high.
drove the car to work this morning,about six miles,perfect no problems at all.drove home it was all over the place.
p rachell

Hi Paul,

OK, sounds like you have pretty much the same symptoms but maybe not with the exact same fault causing them. Try pulling off the connectors on the TB, the ECU temperature sender (brown one not the blue/black one) and giving everything a liberal dose of electrical contact spray. Might be worth scuffing the connector blades with a nail file too. Sadly the access is a pain, but see if you can trace the path of the cables from the TB back and check for any signs of wear/damage. Heat cycles eventually cause the rubber insulation to become brittle.

Good luck!
Mike Hankin

Mike
bought some contact cleaner a couple days ago and sprayed the ecu temperature sender and the throttle position sensor connections,reconnected the battery, fired up the motor,revs immediatly dropped to normal.Have used the car for two days,perfect.
Many thanks to yourself,Will and Rob for your suggestions and referals.
Regards Paul
p rachell

Great result Paul - thanks for letting us know the positive result :o)
Rob Bell

'tis good stuff, that spray. Happy 'normal' motoring ;o)
Mike Hankin

This thread was discussed between 27/04/2006 and 05/05/2006

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