Misfire - Unexpected Fix
Thread Starter
Heel & Toe
Joined: Dec 2022
Posts: 23
Likes: 22
From: Central Ohio
Misfire - Unexpected Fix
I've owned my '04 Z for a little over 2 years now and have had a misfire at idle and low speeds under certain conditions since it arrived. P0300 codes intermittently set.
Last week, I dropped the cradle and replaced the ac compressor, drier, condenser, harmonic balancer, crank seal, and water pump. When I put everything back together, the car fired up and behaved as it always had with a very slight comes and goes misfire. No, I didn't expect any of this work to change that.
The serpentine belt had been getting noisy and I was limping it along with belt dressing. Changed it today and the quality of the idle changed - no more misfire. I've driven it about 40 miles since and I'm calling this case closed.
Probably no surprise to those of you with more experience than me in diagnostics, but thought I would share in case anyone else is chasing their tail and has tried everything else.
Thankfully, the parts cannon was not fired at air/ignition/fuel components!
Last week, I dropped the cradle and replaced the ac compressor, drier, condenser, harmonic balancer, crank seal, and water pump. When I put everything back together, the car fired up and behaved as it always had with a very slight comes and goes misfire. No, I didn't expect any of this work to change that.
The serpentine belt had been getting noisy and I was limping it along with belt dressing. Changed it today and the quality of the idle changed - no more misfire. I've driven it about 40 miles since and I'm calling this case closed.
Probably no surprise to those of you with more experience than me in diagnostics, but thought I would share in case anyone else is chasing their tail and has tried everything else.
Thankfully, the parts cannon was not fired at air/ignition/fuel components!
Instructor
Joined: Nov 2019
Posts: 162
Likes: 80
From: Central NJ
What's the logic behind this?
Only thing I can think of would be low voltage from the alternator caused spark and ignition issues. Not sure how else the serpentine belt would effect cylinder firing.
Only thing I can think of would be low voltage from the alternator caused spark and ignition issues. Not sure how else the serpentine belt would effect cylinder firing.
Thread Starter
Heel & Toe
Joined: Dec 2022
Posts: 23
Likes: 22
From: Central Ohio
Good question. I've heard of the torque tube bushings causing misfires, too, which is odd. My hunch would be something to do with either vibration, or the belt slipping/grabbing at different points in the rotation impacting the crankshaft speed in a way that would throw off the computer's ability to properly time the ignition events. Not sure if that's possible. I think the crank position sensor is involved in misfire monitoring.
