94 4.0 swap 89.b2 low idle

[natmanjoh]

Finished the 4.0 swap into my 89 b2 auto. Only issue I'm having is a low idle. 4.0 came from a 94 explorer. After engine warms up, low idle goes away and it idles normal. When I start it back up, it idles low again. Changed out all normal maintenace items during swap: belts, filters, plugs, wires, fluids, battery, gaskets. I dont know where to go from here or what else to check. Anyone have any ideas?

 

[janderson4010]

Does it change when you unplug the idle air control?

 

[natmanjoh]

Unplugged iac, died right after firing. Plugged iac back in and it started first try, idle still low on cold start. Ran it for 15 min and idled fine. Shut it off, immediately started it again and it idled low again for the next 15 min.

If it only did it when engine was cold i wouldn't mind it at all. But it low idles every time I start engine from being off and lasts 15 min or so. gets annoying really fast especially since it kills engine if it idles too low.

 

[janderson4010]

Well your Iac sounds fine then, try cleaning it out. You might test your coil also, mycoil was bad and it caused a poor idle.

 

[janderson4010]

 

[natmanjoh]

Thanks for the quick response. I'll try both and see what I find out. I'll post results.

 

[janderson4010]

Good luck man, let us know.