I have just completed an engine swap in my 1990 prelude 2.0si. I removed a B21A1 engine and installed a used JDM B20A5.
My problem is the engine lopes at idle after it runs for about 1 minute. If you open the throttle it revs perfectly. The car runs and drives well as long as I am on the throttle. Sometimes when I stop moving and let the engine idle, it will idle correctly.
Initially, I thought it was a vaccum leak, but it idles correctly sometimes.
If I remove the MAP sensor vaccum line, the engine will idle down immediatly, but I still do not think it is idling correctly. The check engine light is not on, but it does work.

Is there any info available on checking the MAP, TPS and the other sensors with a Multimeter? How do I pull the codes from the computer?

I bought this car with a locked up motor and do no know if it had this problem with the old B21a1 engine.

I will certainly appreciate someone with knowledge of these issues responding to these questions. I really want to repair this problem.

Thanks,

Toolpusher

 

The person I purchased the car from told me today that it idled correctly when he owned it. (before the engine locked up)

Any help will be appreciated.

Thanks,

Dennis