I have a 1991 crx si with a b18a1 in it. It has a blox intake manifold with no charcoal canister on the car at all. Alright my issue is when the car it sitting at idle it constantly suges from 2000 to 500. I have already bled the coolant system and cleaned out the iacv valve. What should i do from here?

 

sounds like you have a vacuum leak.

 

Check the ECU to see exactly what codes it's throwing. It's beneath the passenger's side kick panel (under the carpet where the passenger invariably kicks).

 

Check all vacuum lines, then unbolt iacv and clean with carb cleaner, if still experiencing fluctuating idle, try, as inconvenient as this may be, swapping a known good ECU. Unplug and reinstall ECU fuse (or neg battery cable) after each of these actions.

 

i had this same problem with my crx... i have a b18 block with a b16 head and no one could help me either... first check your intake manifold gasket... if that is sealing properly.... check your how you ecu is communicating with your map sensor by checking the voltage

 

Could it be a bad map sensor?

 

a bad map sensor is a possiblity but highly unlikely... a way to check is to leave everything plugged in and use a multimeter to check the voltage at the ecu... for this youll need a pinout diagram and the recommended voltage... check it at the wires coming out of the ecu going to the map sensor... i think around idle is should be around 0.6v or so... how did the intake manifold gasket look?

 

THe intake manifold gasket is good. The reason i think it is the map sensor is because when i take the vacuum line off of the bottom of it it stops idling bad but somkes horribly

 

mine did the same thing... it could be bad but from my experience i would still say its a vaccum leak... take wd40 or some kind of spray similar and start spraying around the manifold... or hoses... when you find the leak it will fix the idle... then just repair as needed... dont go replacing parts unless you are positive it is bad... hondas are notorious for screwing with your head... mine does it to me all the time

 

oh and sorry but i just looked it up again and i gave you some wrong information... your map sensor should be reading some where closer to the 5 volt reference at idle