Hi, I have a ‘90 CRX, and I seem to be having trouble with the air intake or the throttle body, not quite sure which. My cars rpms rise & lower from ~1k to~1.5k consistently. Kind of has the same pace as a rotary engine, brap...brum...brap...brum. Had two mechanic friends look at it, said it could be a vac. seal leak. Any help would be appreciated, thanks!

 

Welcome. What trim level is your CRX, and has the engine been changed, or is it original?

The fuel injection system on these cars are speed-density systems, which means that a vacuum leak (or any unmetered air around the throttle plate) will cause RPM to rise. You need to find where the air is getting in from. It could be a number of things:
Cracked vacuum hose / open port on the intake manifold or throttle body
Bad intake manifold gasket or throttle body gasket (or TB/IM not tightened completely)
Throttle cable too tight, holding throttle plate open at idle (I've also seen a bent throttle plate)
Bad IACV / loose IACV
etc.

 

Thanks for the reply! My CRX is a DX model, and I had recently swapped the original engine for a ‘92-‘95 motor, same series and everything (D15B5). When I swapped it, guy said that there was something wrong with the MAP sensor, switched it from another CRX I have, no difference in performance. I had my mechanic check the hoses and everything, and he said it might be the throttle body? But it doesn’t seem easily apparent what exactly is wrong.