missfire + rev counter needle jumping

[hollowpockets]

after coming home from offshore my car had been sat for 18 days and since starting it 2 odd new gremlins appear, first it seems to misfire under load but only at random, and the rev needle clicks and flickers when the engine is at idle, upto about an indicated 2-3k rpm, even though the engine is just at 800rpm

iv spoken to a mechanic who thought water in the plugs/leads, so opened but they are dry, i made sure with an airline, so next thought is crank sensor, but i dont know what it looks like or where it is, i presume its a replace job rather than adjust.

any thoughts or previous experiences folks?

cheers

graham

[hexhamhc]

Hi Graham. a well covered topic but I would first of all check the anti-surge fuse. Out of interest what volts does it show when running? Otherwise check the crank sensor for debris.
Hope this helps and best regards, Tony

[hollowpockets]

it shows to idle at 12.5 v or above and usually when moving is at 13v or more

i shall go and check the fuse, where is the crank sensor? i do have a small oil leak under the block from something which i havent had a chance to check on a ramp, may this be affecting the sensor?

cheers

graham

edited to add - where is the anti surge fuse?

Edited by hollowpockets on Wednesday 2nd May 11:42

[David Godfrey]

hexhamhc said:

the anti-surge fuse.

whats that then and where does it live?
cheers.

[hexhamhc]

It's the big fuse in the holder above the starter motor. Airbox off, follow the wiring to the fuse holder, open up the plastic cover and there is the fuse. The crank sensor is located on the bellhousing and can also be seen and accessed with the airbox off. Quite often these can be covered in'magnetic'debris. Remove, clean and refit, being careful to keep the original gap sensor to flywheel.
Hope this helps, Tony

[hollowpockets]

i checked and cleaned the crank sensor but still no joy, the missfire is still there.

[VARLEYHYD]

try this one
www.pistonheads.com/gassing/topic.asp?h=0&f=13&t=383324

[hollowpockets]

have also just replaced coil pack and no joy, now think its injector 4, woop woop

i love my tvr

[hollowpockets]

well after checking injectors - nope wasnt them, changed all the plugs and again not right, called dave at automedon who over the phone listened to me start it up and informed me that i may have put the plugs on the new coil pack in the wrong order as the numbers on the rear of the coil pack was obviously the firing order for a vectra v6 (coil pack is a cauxhall item)

swapped numbers 2+4 over and all is well

so the coil pack was the problem after all, car is back to normal but a bit healthier, also fitted a new engine mount (the old one next to the cats came out in 2 pieces.

[Funky]

I had a very very similar problem but it's still awaiting diagnosis. Impossible to start when warm and very very erattic idling all the time and prone to stalling too Glad to hear yours is sorted! Let us know if it happens again!