Idle problem, Wiring issue, 1988 Accord B20B obd1 swap.

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Junior Member
I will just start with the car history. Everything can be found in this thread (scroll through the thread if you want to get to the b20 part). I had no issue for years till I got an 88 model (had to make a new harness), and added A/C to the car.

Current setup is:
1988 Honda Accord Lx-i
Honda CRV b20b
Obd1 p75 LS Ecu, chipped to eliminate ELD and O2 sensor.
2-wire IACV
throttle body with no FITV
megan racing intake manifold
No cel lights (verified working cel light)

The Problem:
The car idles between 1500-2000RPM, once it reaches 2000RPM it drops back down to 1500. It wobbles back and forth between that range. Also the engines does not jars when I let on or off the cars while driving. Turning on the A/C seems to help the problem, but not always.

What I have done:
I have changed and adjusted everything having to do with the idle. Last thing was blocking the air flow to and from the IACV. This actually alleviated the problem, but makes it very had to start in the cold. After that I tried cleaning the IACV, that did not fix the problem. Then replaced it with a brand new one. This did not fix the problem either. I checked the wiring to the IACV and it is all proper. Verified no vacuum leaks. Un-plugging the IACV plug causes a cel light, and car revs crazy (as it should).

I know the problem is with the IACV, but its almost as if the signal going to the IACV is wrong. If anybody has any input it would be greatly appreciated. Thank you.
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Junior Member
After reading around I decided to check the TW (engine coolant) sensor. I unplugged and got a cel light and erratic idle. So I believe that eliminates that. Any input would be great