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MG MGF Technical - Poor Cold Running

Hi. I have a 1996 MGF 1.8i and I have been having problems with it running from cold. I wonder if anyone could point me in the right direction.

When starting from cold, the engine will not run unless the accelerator is applied to take it above 1000rpm. Below this the engine stalls. (I usually start driving straight away rather than just sitting stationary) It stays this way for approx. 3 to 4 minutes where you have to keep these revs on. Sometime it will run, but is constantly hunting up and down the rev range from around 1250 to 500rpm (and then stalls)

After this for the next couple of minutes it will run slightly above tick over (1500rpm) not dropping below this when you dip the clutch to change gear. After this, the engine revs pick up so every time I push the clutch in to change gear the revs rise to around 3000-4000rpm if I let it (I try to change gear quickly!!). After another 3 minuets or so the engine tick over returns to normal operation and then the engine will run fine.

If then left for several hours and started later the same day, similar symptoms appear but not for as long, and not to such a high degree.

The car has been taken to an ex Rover dealer. They had the car for 5 days, replaced the stepper motor, took out and ‘cleaned the dust’ from the ECU and everything was fine for a couple of weeks, but then the problem returned. When connected to the Rover computer it says that everything is running within the correct parameters.

Any ideas??
Nigel Griffith

Hi,
Check the brown coolant temperature sensor,unplug it,and see what happens.

Simon
SCJ Connolly

Simon Thanks. Tried tis today, the engine struggled to fire and would only hold revs onthe accerator. Cooling fan was on all the time which I suppose it should. But otherwise no joy. Any other ideas out there?
Nigel Griffith

Unseating the ECU & then re-seating it making the symptoms go away for several weeks points to a poor connection on the ECU. Get them to do the same again, only this time paying a bit more attention to the condition of the contacting surfaces.
bandit

I have recently purchased a 1998 vvc which has developed an intermittent fault. On cold start up the side intake fan comes on along with the temperature warning light! The engine struggles to tick over and runs on low power with high exhaust fuel emissions. Up until sunday this problem did seem to clear intermitently and the car ran fine, but then the problem kept returning. I have already changed the engine coolant and ambient temp. sensors but no joy. It is very frustrating!!!!!
I have booked my mgf into a rover specialist next friday to hopefully diagnose the fault. :(
Mike Booth

Mike, that sounds like bad/intermittent connection either at the ECU or the temp sensor end of the wire, or an internal break within the wire or a short to the bodywork. An inexpensive multimeter should help identify it.
Charles

This thread was discussed between 29/04/2008 and 21/05/2008

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