watman02

do you have 12volts at the injector??? can you do a compression check???? do you have a manual with wireing diagrams?? if so check the wireing from the injector to pcm and coil to pcm. also since you just changed the harness are you sure all the grounds are installed properly????

boothay

I haven't checked the wiring and im going to get a compression test done within the week. Making sure all the grounds are connected im not sure what you mean by that.

cliffyk

Another thing to do is check the compression (edit--whoops, watman' already said that).

It is common to assume an ignition problem when the misfire DTCs are reported, however because of the way the misfire monitor functions immediately swapping out ignition components is not the best way to correct the problem.

The misfire monitor works by using the crankshaft position sensor signal to calculate the crankshaft acceleration rate, created by each cylinder's firing. When the acceleration rate falls below a calibrated value, a DTC is stored if it occurs over 200 revolutions, a DTC is thrown and the SES lamp comes on if the misfire happens over a 1000 revolution window.

The PCM has no idea what caused the misfire--it could be no spark, no fuel, no air, no compression or any combination--so they all need to be checked before parts are thrown at the problem...

boothay

Ok so when I check the compression checked and theres compression,Whats the next step because like I said I changed almost everything around that cylinder. My question is could it be the crankshaft sensor itself, or maybe even the pcm? Have you guys ever hear of a pcm going bad on just one cylinder?

cliffyk

The compression needs to be 130psi or better in all cylinders (and that is the very bottom end), and the lowest cylinder needs to be no less than 75% of the highest cylinder's reading. However even with the lowest 75% of the highest you may get misfire codes if it is just one cylinder that is that low.

It could be a bad CKP, do you actually feel the misfires?

boothay

Yes I can feel the misfires, but if i drive it long enough it goes away then comes back. Its odd.. I only drove it like once since its been doing it.

cliffyk

That you feel the misfires indicates that they are real, not the product of a faulty sensor--do that compression check...