Not for sure I should post this in general or not but here goes.

I swapped in a 96 3.4, since the swap i have had an extremely high idle 2400+. I have gone through as many threads I could find and nothing has given positive results. I am using BlueDriver ODII diagnostic software, when running live diagnostics it shows a warning of insufficient cooling temp for closed loop fuel control. Its not throwing a CEL but it is showing this warning during the live scan.

I have seen post stating that both o2 sensors need to be working or this could cause an issue with throwing the P0125 code. Motor only had (1) o2 sensor and that is the down stream sensor. When I did the swap I bought an aftermarket o2 sensor for the year of the motor.

I have unplugged vacuum lines and the idle has dropped to somewhat of a normal idle but it runs rough. Could I possibly have a vacuum line swapped? I haven't found a very good vacuum diagram for the 3.4 online.

Throttle position sensor. I know those are supposed to be set at a certain voltage. When I loosen the screws to adjust it while running I get momentary drop in idle, then goes back up.

IAC and AFM have been cleaned. I can unplug the IAC while running but no changes in idle. Tested ok when ohmed out same as AFM.

Temp sensor, when unplugged while running does not change idle either.


Any help would be greatly appreciated, Thanks

 

You've made a wiring mistake. Obviously start with the coolant temp wire. Just take a step back and then thoroughly examine it.

 

The harness was made by ORS. The motor has been sitting for quite a while. Sensor ohm's out ok and the live data and temp gauge seem to be correct.

I just feel like i'm overlooking something, something simple as usual.

 

Where does the line for your throttle dashpot go? I know I have seen about 200 photos of that plugged into a vacuum line and it seems to lower my idle when it has zero vacuum. Its actually supposed to go into the air intake and not be connected to a vacuum.

From experience you only need the front O2 sensor hooked up to run in closed loop. The important things here are your MAF and your O2 sensor in the back. Hows is your MAF wired.

What ECM and wiring harness are you using? I had to rewire my MAF twice to get it right.