i have a 94 lude w an h23 vtec, this car was originally vtec, i did not fabricate or mess with wiring harness. my problem is that the motor revvs up to around 2800 and then drops down to around 1200, i have researched on hondatech and i toought it might have been my iac, but i replaced it and it does the same thing. i resently put on a vafc2 with a boomslang harness, the car did not want to run without the vafc, i have checked the codes and it gave my a code 21 and a map sensor code. but the codes do not come on when the vafc is plugged in. most recently i have unplugged the boomslang harness and the car runs now but revves up the same way at idle with the check engine on. o i have also replaced my vacuum hoses to the map thinkin there cud be a leak there. someone HHHEEELLLPPPPPPPP

also if anyone can give me a link to diagnose a map sensor, it wud be appreciated

 

Don't drive around too long with ur map sensor code, if ur map sensor is bad ur ganna get terrible gas mileage and run extremely rich and foul things up. If ur gettin the code, I'd first take it out and clean it then if u still get the code, replace it, if u wanna test it, turn ur car to the on position but don't start the car, then check the voltage going to the map sensor, it's the middle wire going to the map sensor, u should read 4-5 volts, at idle it should read .5-1.5 volts.
Code 21 means ur Vtec solenoid is opening, U can check the solenoid by directly giving it 12 volts from the battery, u should hear a loud click. Good luck diagnosing, hope u get it fixed.

 

check for vacuum leaks or a leaking im gasket

 

sorry to interrupt, but how do you clean the map sensor? would you possibly be able to show a picture for the mechanically challenged such as myself? thanks in advance.

 

thanks guys ill try these things tonight after work, but can you also specify how to clean the map.