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MG MGF Technical - shakey engine!

when i press the clutch on my VVC and the revs drop down to about 1200rpm , the engine shakes causing it to nearly stall, It also shakes just when idling, its not the idle control valve and its not the head gasket, so has anyone got any ideas what to check next.

cheers

Gazza
gary robinson

Mis-firing? How old's the car? If more than 3, I'd suggest changing the plugs, and have a look at the condition of the HT leads.

There are quite a few other things it could be though.

Leigh

Leigh

.. and the distributor cap.
Dieter Koennecke

BUT DIETER, REALLY !!! on a VVC ??

Got You .. :)
Regards , Carl.

PS, probably a broken inner connection in one of the ignition cables. If You have an Ohm-meter , check for a few kilo-Oms on every cable . If more or totally open circuit the cable is gone... When at it check the 2 ignition-coils for rust /delamination. The underside of the coils can rust heavily = bad spark.
Carl

*g* got me, first read, then think, then write ;)
Dieter Koennecke

its got new plugs n leads on boys! so what else can I check?
gary robinson

if you can, check the condition of the plugs. make sure all 4 are ok & in same condition.

regards
Jason

Revs DROP to 1200? What's the normal tick-over?
George B.

the tick over is about 8-900 ish, I just meant the engine shakes just before it hits idle speed
gary robinson

Low rpm misfire can point to either a duff plug or a pretty big leak from the cylinders, such as is found when a valve burns an edge. Here when revs rise there is less time for the cylinder pressures to escape so there is less power loss and less imbalance.

Firstly remove the plugs and examine the electrode ends. The misfiring cylinder will have a plug running in different conditions leaving different deposits. Do check the gaps are correct!! Also be aware that plugs can be faulty from new and you may have a plug which is breaking down. So when you find the affected cylinder try another plug and see if that makes a difference.

If the plugs are OK then you have to do a compression check, first dry and then wet. Any leakage will of course be very obvious at cranking speed and if it is a valve then the wet test will show little difference.

If compressions are obviously out, and this means that it will be way more than the normal range of 20 psi between the lowest and highest reading, then the head will have to be lifted for full examination and appropriate rectification.

Rog
Roger Parker

This thread was discussed between 12/05/2002 and 18/05/2002

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