V-8 Mis-fire

Poledriver · Mar 13, 2009

I've had an intermittent mis-fire for some time now. Symptoms:-
Can happen at any speed, in any gear, under load or constant speed.
Seems to be complete loss of power (all cylinders), feels like traction control has kicked in. Tried switching TC off, no change!
Dropping revs then accelerating again does not clear the problem.
Changing gear (up or down) does clear the problem for a while.
No engine warning light!

Diagnostics:-
I've fitted new air filter.
New plugs.
Checked Fuel Filter clip OK.
No water in rear spark plug boots.

I've bought an OBD2 code reader, it does not show any problems1

Any thoughts?

Stu C · Mar 13, 2009

Not a wiring problem is it? I know on the L-series derv engines, people report engine running lumpy etc.. and where the wires run over the side of the engine it breaksthe wiring. Have a look see everything is in tact...long shot i know but worth a try

mattk · Mar 19, 2009

I had a very similar problem in my old R620 ti. Thought it was something massively wrong with the engine... Just needed new HT leads. Worth a try maybe ?

Stu C · Mar 19, 2009

Ah yes, could be one of the coil packs breaking down. IIRC black olive on the 260s had the same problem. He changed one of the coil packs and was sorted

anthony27 · Apr 10, 2009

It could also be the petrol pump.

this is known to fail or cause trouble. Obviously, it is a BMW part

Does the problem occur more frequenly when you are below half tank?

JMCSMITH1 · Apr 22, 2009

Misfire

I had a similar problem on a Rover V8 - stranded me on a roundabout in Dudley! Called the AA, who instantly diagnosed the fuel pump under the rear seat. The patrolman made a simple roadside mod, replaced the seat and the car was fine. May be worth checking out the fuel pump - it's a common problem he said.
Cheers.

V-8 Mis-fire

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