Hi all. I recently did a bunch of overdue maintenance on my M20 including timing belt service, valve adjustment, new CPS, new coolant temp sensors, new plug wires, plugs, cap and rotor, and rebuilt 415 injectors. The car runs great and has a steady idle at 750rpm.
After that, I replaced the motor and tranny mounts with 635CSi and UUC black urethane parts. Immediately, I noticed a slight vibration just of idle at about 1k rpm. It disappears pretty quickly, then comes back stronger at 1750 rpm, then disappears again about 2500 rpm. The car idles fine, pulls to 6k rpm no problem, and the vibration occurs both with the car parked and in motion. I first thought it might be a bad harmonic balancer, but it seems odd that the vibration isn't more consistent. I also suspected the new injectors, but I pulled my plugs and they all have a nice toasty appearance with no wetness.
I searched the archives but I didn't see any problem quite like mine, and I'd appreciate any help anyone can offer.
After that, I replaced the motor and tranny mounts with 635CSi and UUC black urethane parts. Immediately, I noticed a slight vibration just of idle at about 1k rpm. It disappears pretty quickly, then comes back stronger at 1750 rpm, then disappears again about 2500 rpm. The car idles fine, pulls to 6k rpm no problem, and the vibration occurs both with the car parked and in motion. I first thought it might be a bad harmonic balancer, but it seems odd that the vibration isn't more consistent. I also suspected the new injectors, but I pulled my plugs and they all have a nice toasty appearance with no wetness.
I searched the archives but I didn't see any problem quite like mine, and I'd appreciate any help anyone can offer.
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