1990 Prelude High Idle and fluctuation JSPEC motor

HELP!!

I just bought a 1990 Prelude with a 2.1 motor with a bad timing belt. Put a new belt on and the idle fluctuated up and down from Idle to 3000rpm. Cleaned and tightened down the inside of the fast idle control and the vehicle idled perfect and ran fine until I blew up the motor (burned through an exhaust valve at 169K miles on the motor and car).

I Found a JSPEC B21A and installed it using the JSPEC intake. I blocked off the EGR pipe, but hooked the valve up electronically so I did not have to bypass it.

Now that I have started the car, it runs immediately up to 5500rpm and back down almost stalling, then back up again to 5500rpm. It continues to do this constantly.

I used my USA throttle body. I checked for leaks, could not find any. I replaced the three idle components from my USA intake (which worked fine on the old motor) EAVC, Fast Idle, ISC, but it still is doing the same.

I disconnect the EAVC and the idle still revvs up and down and backfires, but at a respectable 1000rpms.

Does anyone have any idea what I am missing or overlooking???? Could it be in the fuel injectors?? I have not adjusted the Idle Screw yet.

If I bump the throttle, it will react, but at a much higher RPM and I am afraid of blowing up the new motor.

Thanks in advance for any help.

Tim McCreary

I found the problem!!!! I checked the injectors and fuel pressure regulator to rule them out. Also the MAP sensor and all other items.

I then sealed the throttle body opening and it started and ran with no air flow coming in there. I assumed then that the intake gasket was no good or not sealed properly.

When I bought the motor, it appeared the intake was torqued down. Little did I know that the person who did this neglected to purchase an intake gasket and install it.

I thought about removing and retorquing several times when the motor was out of the car, but felt the other person knew what they were doing.

Hint of advice, NEVER DOUBT YOUR INSTINCTS and take a few more seconds to double check. This was MY MISTAKE for assuming.

Thanks for listening.

Tim