Hey guys,

So I have an '86 GT that I just did the maf conversion swap and now has high idle when warm. I used a harness from late model restore, 94gt maf sensor and housing and a A9L computer out of a 91 gt 5speed. I have not hooked up the fuel pump relay or VSS wiring. The maf harness instructions I got said nothing about it. So I put it in, fired right up and idled fine. After driving the car around and letting the computer learn it now wants to idle at 1500rpm when warm. when the care is cold it idles at 600rpm. Before the car was switched to maf it had absolutely no idle problems.
any thoughts?

 

I didn't really follow the 90s Mustangs, but wouldn't they 94 have the 4.6 L engine? I'm wondering if that MAF sensor was set up for a '94 4.6 if that wouldn't be compatible with your 91 computer. These are total guesses, I'm shooting in the dark here.