Hi guys

Nearly cured my misfire problems but i'm stumped now.

Car now only misfires under acceleration. Its like stop start, almost like throwing a switch.

It's nearly caught me out on some close overtakes.

Any comments gratefully received.

are u sure its misfire and not fuel starvation, just a thought as i think that is where my problem lies

It could be.

I'm going to fit an oil pressure guage to the fuel system so i can monitor fuel pressure.

I think these are the only guages that read high enough. (45PSI?)

could it be a bad TPS? or a dirty connection on the PTU?

PTU seems ok, and all connectors have been cleaned.

TPS voltages check out within tolerances.

Sounds like something breaking down under load, plug, coilpack, injector.

I agree,

Ive just fitted a new set of plugs so I don't think thats the problem.

Can the coil packs be tested in some way? DC resistance or something?

I've heard you can rig up LED's in the circuit to check for poor connections. Does anyone know how this is done, i,e where do you put them?

you could put a strobe light on a coil pack at a time and modify a lead so you can drive it with the strobe in place to identify the dodgy cylinder.

mine used to missfire under acceleration when the air filter got wet and the MAF got damp air on it.

i can only imagine that the LEDs show the power to the coil pack and not the actual HT output. the only way to test that is with a strobe.

 

Could a bad connection on an injector cause the missfire under load? if it was high resistance connection, it might be ok when there isnt much load, but when you accelerate and the injector wants to stay wide open, the voltage drops across it and it closes,

Went through something similar with mine and it turned out to be the autobox on its last month of life. I think the misfire sensation was clutches slipping and biting again.

Ultimately it lost all drive and the overdrive lock up clutch stopped working a week before total failure. If its an auto you have take a look at the clarity of the fluid and smell it. Otherwise ignore this!