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MG MGF Technical - misfire after generatorbelt breakdown

Hi All!

I had a generator belt breakdown on my MGF VVC. This result that the camshaft was turned 30´. This result in that the camshaft sensor didn’t work properly and the car ignition didn’t work (the car did only work on two cylinders). Now are the generator belt and the cam belt changed. The Camshaft is turned right and the valves are check. But the car doesn’t ignite like I used too do. The car is misfiring and lots of smoke is coming from the exhaust. The plug and leads was changed just before the generator belt breakdown. Do anyone have some tips what I will look for too find the problem?

Thanks, I really need help!

/Mark
Mark

Wow - that sounds like a nasty problem.
Which camshaft was 30deg out ? - the inlet cam for cylinders 1 and 2 ? - this might explain why it went to 2 cylinders.
What's the smoke ? is it oil/petrol or water ?
Is it firing on all cylinders ?
Are you sure that all camshafts are now lined up correctly: the VVC has 3 - one normal exhaust cam, and two inlet cams - one driven from the main cam belt, the second (for cylinders 3 and 4) driven via the exhaust cam and a belt at the rear (geabox end) of the engine.

Steve
Steve

Don't understand why a broken generator (alternator) belt should effect the cams.

Ted
Ted Newman

Ted, debris from fragmented belt jams into the gap in the timing case and can cause the timing belt to jump.
This can of course lead to bent valves ,which may be the case here.
mike
mike

All I can say is bring back chains for the cams.

Ted
Ted Newman

>All I can say is bring back chains for the cams.
I think that electronic tagging would be more humane ;-)

If the timing was out then you might have dammaged the pistons or the valves, do a compression test and check if you have equal and good compression on all four cylinders.
Will Munns

Hi all!

The shafts are now in right position. The compression test shows equal and god compression in all four cylinders. It sounds that the cars ignition timing is false. The test computer shows no electric false.
The smoke is white and does not smell gasoline.
What left too check for?


/Mark

mark

>The smoke is white and does not smell gasoline.
>What left too check for?

A drop in water level, the 'smoke' could be steam from a faulty head gasket or inlet manifold gasket.

How old is the car? Inlet manifold gaskets are known to perish on older cars(black gasket) and they need replacement with one that doesn't perrish (green gasket)

Will
Will Munns

>>What left too check for?<<
Ignition leads attached to correct plugs
12V (LT) leads attached to coils (try disconnecting one of the coils at a time).
Do you have any devices to see if a spark is reaching each plug ? (like a strobe light or similar ?)

If you're really stuck, then take each plug out and check its condition - this should tell you which ones have been igniting petrol properly anad which are failing.

Steve
Steve

>see if a spark is reaching each plug ? (like a strobe
>light or similar ?)
A strome light is unlightly to help, but you can buy things with neon lights that you insert between the top of the plugs and the leads. Because the plugs are so deep in the head you have to be in a unlit garge to see if they're going off, but this also gives you an opertunity to see if there are any other stray sparks running around.
Will Munns

I'd actually use an oscilloscope - one of the greatest pieces of test gear ever. You attach it, it draws a picture of exactly what's happening - far better than any 'computer diagnostics'.
But for some reason they are deeply unfashionable.
Steve

>I'd actually use an oscilloscope
great if you have one

>But for some reason they are deeply ...
expensive for very little other hobby usefullness

Will
Will Munns

This thread was discussed between 30/04/2003 and 01/05/2003

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