IACV code and surging miss

We may earn a small commission from affiliate links and paid advertisements. Terms

flash3825

New Member
I bought for my son a '96 Civic EX with a '92-'95 D16Z6 engine, P2P A81 ECU and an automatic transmission. The IACV wiring was converted from a 3 wire plug to a 2 wire plug and the throttle position sensor was replaced, neither one helped. I have two problems that I’m trying to solve:

1. surging miss at 1600 RPM – just finished tune-up, plugs, wires, cap rotor and fuel filter, cleaned IACV and throttle body, replaced distributor

2. check engine light on with one code – P1509 - IACV circuit

Any possible solutions would be VERY appreciated. Thanks!
 
Do those cars have a fast idle thermo valve (FITV). I'm pretty sure the obd-1 cars all did. Anyways, there is a threaded cap inside the part that backs out. This doesn't let the valve close, so you get a surging idle once the engine warms up. It's an easy fix. Just pull the cap on the housing and screw the valve back in.
 
Do those cars have a fast idle thermo valve (FITV). I'm pretty sure the obd-1 cars all did. Anyways, there is a threaded cap inside the part that backs out. This doesn't let the valve close, so you get a surging idle once the engine warms up. It's an easy fix. Just pull the cap on the housing and screw the valve back in.

Thanks for the information. It turns out that I needed to change the IACV to the 3 wire IACV so I changed the throttle body to the '96-'00 throttle body and it had the newer 3 wire IACV. Once I wired it up the miss was gone and the IACV code was gone. I still have the CEL on and a knock sensor code because the OBD2 ECU is looking for it and my D16Z6 engine doesn't have a knock sensor. Any ideas on how I can get rid of the knock sensor code and make the cel go off? I'd prefer not to just take the light out.
 
You can get a OBD2-OBD1 jumper harness and run the P28 ECU (D16Z6). But that may lead you to switching back to the other throttle body.
 
The only OBD2 to OBD1 jumper for an automatic trans available is through Rywire at a cool $250. The owner of Rywire called me and advised against the jumper and now I'm glad I didn't buy it. I have an automatic trans and I got it operating real well with a swap of ecu's (both OBD2) - the P2P A81 ECU stock. The ECU that runs everything the best is the stock OBD2 that came originally with the '96 Civic, it turned out that the ecu in it had mods but now that I have the stock ecu it works real well. The only problem left to solve is the CEL and the knock sensor code. Not too long ago a guy said I could ground one of the pinouts but I don't know how to do that and I'm afraid that might screw things up - any ideas?
 
Back
Top