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MG MGF Technical - Still playing up...

Hi all

My 96F is still playing up on starting. Hot, cold, damp or dry when you start it, for the first 5-10 seconds it judders horrably and the revs jump between 200-800. There is also black sooty smoke. After the 5-10 seconds the car is fine. Any ideas?
J Price

Sorry James, I may have missed a previous thread where you've already covered what you've looked at so far.

If not already done, then:

* consider replacing the HT leads ± spark plugs.

* If your car is an MPi, then consider the replacement of the distributer cap and rotor arm.

Rob Bell

Cheers Rob

I have changed the HT Leads + plugs, but that didnt help. I will look in to changing the distributer cap and rotor arm.

It is just odd that it runs fine apart from 5 seconds at start up :( It allways starts first time :(

Could it be something to do with the choke?

The black smoke would indtcate it is not combusting properly, not enough air?

Cheers

James
J Price

Hmm, yes the choke idea is a good one. The K-series throttle body doesn't posses a choke as such, but does have an idle air control valve (IACV).

Might be worth popping the pipe off, to ensure that there isn't a blockage, and then check the IACV stepper motor function.

The IACV tube is the upper of the two rubber hoses entering the TB - more on the TB at http://www.mgf.ultimatemg.com/Throttle_body/index.htm
Rob Bell

>>There is also black sooty smoke<<
And after the 5-10 seconds startup period, the smoke goes ?
Perhaps something is entering the engine after switch-off or while the car is standing (engine off) ?
Are you using coolant or oil ? Does the smoke smell of petrol or oil ?
If, for example, a small quantity of oil enters one cylinder then the engine may be rough while this oil is cleared.
Could one injector be sticking ?

What condition were the plugs in when you changed them ? were they all the same condition ?
You might need to run it for a few seconds and then examine the plugs before the engine clears the condition.
Steve

I'd go for Robs idea on the IACV (Stepper motor) and wiring from the ECU to the motor.
I heard from someone who had nearly similar problems recently. Found a wire rubbed off the isolation near any bracket at the ECU (missing cable tie).

Just an idea.

Dieter
Dieter K.

Thanks Guys

I had a look at the IACV lead and it all looked clean but I couldnt find the motor?

When I changed the plugs they all looked the same and in good nick (the car has done 25K miles).

I am pretty sure the black smoke smells of petrol but that could just be the starting of the car?. This does correct itself after the 5-10 seconds.

Thanks for the help

James
J Price

>all looked clean but I couldnt find the motor?

The IACV _is_ the motor. Just where the cable connects to ;)

But don't forget to check wires at the ECU as well.
Dieter K.

It has gone in to the garage now, and apparently they are just going to put a new ECU in. So hopefully that should fix it. I will keep you posted :)
J Price

Fingers crossed James!
Rob Bell

This thread was discussed between 24/06/2003 and 26/06/2003

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