S4S Misfire

[ledders]

Can anyone help me with this one, I have a 1995 S4S which misfires badly under heavy accelaration. I have fitted new plugs,leads,fuel filter, and a lotus dealer has fitted a new wastegate actuator, ECM, and now tells me they have done everything they can!
The problem is still there as bad as ever and I have no more ideas, has anyone got any clues?

[ErnestM]

Did they check/replace the MAP sensor or the line running to it?

Just a thought...

ErnestM

[oharedm]

Andrew,

I emailed you off list. Did you get it OK ?

Regards
Dermot, Oxford

[thomer00]

This maybe daunting but I heard this the past weekend. Sometimes the grounds on one of your connections could be to blame. Now I dont have any idea how many leads you have, but if you were to start with the ones you can access, I'd unplug them, file them down with an emory cloth, get some dielectric grease, grease them up lightly and reconnect. This problem could be electrical.

[MikeyRide]

I just love it when a shop throws parts at a problem rather than figuring out what's actually wrong.

Is it definitely an ignition miss? I've had an O2 sensor in another car go bad in a way that it caused extreme richness. Felt like a miss. In fact, I replaced a cap/rotor/plugs/wires first. Failing that, I actually started thinking about the problem and noticed that the car ran just great when it was dead cold and (not coincidentally) the O2 sensor wasn't working yet.

Does it misfire if you accelerate hard with a cold engine (I know, I know, you shouldn't do this but it's in the name of testing)? What if you disconnect the O2 sensor?

It's a long shot but worth checking.

[chuckgeo]

Your fuel pump may not be up to specs.
My car did mis-fire under a load.
I put in a GM pump for a V8 and the
mis-fire went away.

Car idle better with the new pump