I have a 1996 jeep grand cherokee 5.2 l v8. I noticed it it start to miss fire and the check engine light came on. you can feel it misfire at an idle and while accelerating slightly but when u reach 45 mph it starts to misfire bad(feel it shake the car) and it seems to get better after 55 mph. took it in and got the codes ran, got the code 43 for multiple cylinder misfire in all 8 cylinders, checked most everything in the service manuel and nothing major seems to be out of place. i think it might be a sensor of some kind just wondering if anyones had a similar problem or if someone can lead me in the right direction......:runaround:

Welcome to AF.

It might simply be a maintenance issue. Unless you have done so recently, try replacing the spark plugs, plug wires, distributor cap and rotor.

Code 43: Ignition control signal from the PCM did not achieve the expected maximum current flow of 8 amps. The coil output circuit inside the PCM is designed to limit current flow to 8 amps, but this can only be reached if coil resistance is normal, the PCM output circuit is normal and full battery voltage reaches the battery side of the coil.

Check the battey voltage to the coil,(DG-OR wire), from the automatic shutdown relay. Check for normal coil resistance,(See below). The dwell time on the PCM coil control output should be near 4 milliseconds, (Need lab scope), with maximum or peak amps near 8 amps. The coil control wire is GY or BK-GY wire going to PCM pin A-7.

Ignition Coil Resistance

Primary (Ohms) Secondary (Ohms)
Diamond: .96 - 1.18 11.3 - 15.3 K
Toyodenso: .95 - 1.20 11.3 - 13.3 K

Hope this helps.

Moving to the Grand Cherokee section for you.

I recently ran into a 99 with a similar problem. Computer was giving a similar code, after 2 hours of waveform diagnostic, I went back to basics. Turns out one cylinder had no compression, melted the exhaust seat right out of the head and threw a valve. Check basics..!!!

HAY YOU KNOW I HAVE A VERY SIMILLAR PROBLEM AND HAVE BEEN GOING OVER IN MY HEAD AND YOU MAY BE RIGHT ON THE MONEY. I HAVE SEEN THIS PROB BEFORE AND TURNED OUT TO BE A BAD COIL. i WILL CHECK MINE OUT AND GET BECK TO YOU. THANKS, GREAT TO HAVE A SECOND OPINION.......NEVER GO TO GARAGE HAHAHAHAHAHAHAHAHA!!!!!!!!!!!!!!!NEVERRRRRRRRRRRRR RRRRRRRRR

Nope no luck, still there. Please anyone throw me a bone? Can't have a jeep down guys. Cant get muddy if it aint running thru da woods.