EG2NV

Hi,

im running a b18b in my 1999 Civic EX with obd1 p75. On cold start, the car idles between 1500-1700rpm. When i touch the gas lightly it revs higher, stays there for like 2 seconds then drops back to 1500 again. Sometimes it jumps up and down irradically but when the car is at operating temperature it runs fine and idles normally. Also, when at normal temperature the temp gauge drops a bit after like 20 mins or so and starts runnning rich at 1500rpms then gets warm again. When i put a P2T(Sir) OBD2b ecu in, the car runs perfect. idle is perfect but runs fine, its just not as strong as the p75 and cuts off at 6500 cuz of vtec. So doesn't this mean the IACV and FITV is fine?. iacv 2-wire fix was done, coolant topped and no bubbles.

I don't understand why a P2T obd2b would run perfect but my p75 obd1 has irradic idle & dropping temperature readings

Any suggestions? could it be the ECU?
Searched all the forums and none relate to the fact that when i put a different ecu in, it idles perfect.

bbarbulo

iTrader: (2)

I would double check to make sure your OBD2b to OBD1 conversion harness is correct. It could have some wires mixed up that make it run poorly.

civicmaple96

Check idle control valve also