IAC and injector issues. Running great one sec, bad next

[legacymax]

I have a 94 touring wagon with 5spd swap and ej20g, new wrx Coil on plugs. It is running off of the stock ecu.
Lately it has been running great until today.

I have had issues with IAC before and they have returned. When I turn it on it idles at about 2000-2500 rpm. When it comes up to op temp the rpm comes down and idles normally. When it is coming down, it gets to 1000rpm and the throttle blips a few times, throws a CEL, and then idles down. Then it drives perfect. To get the idle to come down the vehicle has to be stopped.
Last week I changed the IAC out and it ran great. Fell in love with the car again. Then today on the way to get it emission tested, I went to accelerate and it starts running horrible and throws a CEL. Great timing. The car would go in and out of running great/bad on the way home.
I checked the codes and they were 15(injector circuit issue) and 24(IAC circuit issue). I tried unplugging and messing with the injector and it fixed the code 15 issue for a little while and then back to running bad.

So, these problems seem to happen together. Is there any common circuitry between the injector and the IAC? Maybe a ground that could be loose? This problem is very frustrating and it really makes me not trust the car.

Any input would be much appreciated.
-Max

[Legacy777]

I would recommend checking the resistance of the wiring from the IAC & injectors to the ECU to make sure it shows 0 ohms or close to it.

I wouldn't necessarily say you're having two separate problems, but possibly that the ECU is just throwing those two codes. Sometimes it does that. To make sure though, I'd suggest checking the wiring on both and go from there. Also, check the resistance of the injectors and coils on the IAC.

You can find all the diagnostic info in the factory manual on my server.

http://www.main.experiencetherave.com/s ... and_Elect/

[legacymax]

Great, Thanks for the reply.
I will be checking both of those and checking the ohms on the injectors. Do you know what the injectors are supposed to be? I guess could check the diagnostic pdfs.
-Max

[Legacy777]

11 - 12 ohms