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MG MGF Technical - Electrical problems

Hi All
As usual, thanks for all the previous advice given.
Can anyone give me any pointers re. an electrical problem I have? Last Saturday I replaced my MGF's battery, spark plugs and leads. The battery was correct for the car, the spark plugs are BOSCH, and also correct (according to the shop), and the leads are the blue high performance leads from Mike Satur.
The old plugs were filthy black, as were all the visible connections. I cleaned everything using proper connection cleaner until it gleamed, and I am pleased to say that the car is now much more responsive, and a little quicker. The only problem is that the tick-over is about 300 rpm higher than it was, it now runs at 1300 rpm when warm. She has always ticked a little fast, but this is too much. The only way to bring down the tick over rate is to run one of the more power hungry electric motors in the car, i.e.: the electric windows, or full beam, whereupon the tick-over drops by 200 or so.
What is going on? Mike Satur, if you are out there, have you seen anything like this before?

All the best

Jim
J. A. Farrington

Have you tried resetting the idle RPM?

This is done by turning the key to ignition NOT STARTING THE CAR.

Then press the throttle 5 times.

Return key to off and start car.

This may help.

Johan
Johan Slagter

Actually, sounds like you have not reconnected the IACV, which is the black box on the throttle body.

To test, do as Johan states and when you switch off you should hear a whirrr, clickey clickly click noise - if you dont then this is your problem!
Will Munns

Thanks v. much for the advice guys, I've already tried re-setting the TPS, and I do get the whirring clicking noises as expected. This does not seem to make much difference, and would not explain why the revs would drop when I use the electric windows / put the main beam on.
All the best

Jim
J. A. Farrington

Thanks for the advice so far. It was suggested to me that the voltage going into the ECU must be surging for the revs to drop as the window motors go on. I have been told to check my earths. The only earth I messed about with is the one coming out of the distributor cap (when I changed the earth lead). Could a faulty connection here cause the problems described above?

Cheers

Jim
J. A. Farrington

>The only earth I messed about with is the one coming out of the distributor cap (when I changed the earth lead).

???

Did you touch the airfiler/throttlebody. It could be that the throttle is not shutting properley, and the IACV cannot account for the diffrence.

The only reason why the idle doesn't change when you switch the lights on normally is because the iacv opens slightly, if the throttle is jammed open then the iacv will do it's best to shut off the air, but end up fully closed and _still_ idling high.
Putting on the lights adds load to the engine, up untill the extra load pulls the idle below 900 the IACV is still trying to pull the revs down, after the load is exceeded the iacv will open enough to pull the revs back up to 900.
Will Munns

Thanks for taking an interest in my problem Will, and offering advice. In your opinion, is it possible for the jubilee clip on a K&N filter to distort an ALLOY throttle body if overtightened?

All the best

Jim
J. A. Farrington

In my opinion, yes, but you'd have to be using a really strong clip!! (so you can scrub that).

Open up the boot and check if the throttle can be shut by hand any further (you could use a feeler gauge or paper between the endstop screw and the throttle cam) if so then you might have a sticky cable or have disturbed the adjustment by changing the routing of the throttle cable - I assume that this is adjustable (mine is, but then I'm using it with a bike gear cable in a diffrent engine bay!)
Will Munns

Will, pleased to tell you that I managed to solve the high tick over problem. As my dad said: "If you replace cr*pped up plugs and leads for stonking new ones, and clean all the connections till they sparkle, you will get more power to your foot my son. More power to your foot = engine sucking harder through throttle = need to close butterfly and slow down the tick-over, try using the little screw on the throttle body designed for this purpose. Doh!
Mmmmmmm.....donuts...

Cheers

Jim
J. A. Farrington

This thread was discussed between 08/11/2004 and 15/11/2004

MG MGF Technical index

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