Bad vibration at 3000 RPM and misfire throughout RPM range.

[jday240]

1990 Coupe w/ KA24EEngine has all emmissions removed, including secondary butterflies and scv.

I refurbished the motor mounts w/ polyurethane recently and can feel a bad vibration at 3000 rpm and a miss throughout the rev range that clears up around 5500 rpm. I have an underdrive crank pulley as well.

There is more vibration felt at idle then at 6000 rpm w/ these mounts installed. I was curious as to whether all KA motors run this way. I have driven a 240 since 1999 and am on my third at present and never noticed this before. I am thinking the misfire could be related to the coolant temp sensor. What is the sensor in the lower radiator hose and can it be found aftermarket? Mine has a damaged harness and the wires inside are badly corroded.

Any other suggestions would be appreciated. I have not used the diagnostic mode on the ecu since I got the car running.

And yes I searched several times in the past month.

[SOHCSE]

Injectors?

[jday240]

I don't think it's injectors because it is not at regular intervals and seems to go away above 6000 rpms. I have a new set of injectors that I can try though. I still have no idea about the vibration ... I may swap out the mounts w/ another set.

[yessir240]

i had a somewhat simmilar problem.. make sure your spark plugs are all the way in... atleast thats what my problem was i was like DOH... i think one rattled out on me? idk

[Florida240sx]

Timing/spark