FordxFour

Hello everyone. I am in dire need of some information from the mustang crew.
I have a 1990 f250 with a 302 (Ya I know its a truck). I have recently done a mass air flow conversion using the A3M1 computer and MAF out of a 1993 Mustang GT HO. I bought a MAF conversion wiring harness to hook it all up. Roughly for motor specs its a 5.0 with Port and polished heads, Camshaft out of a later explorer (same HO firing order just more for low end torque), Bosch III 19lbs injectors, msd dizzy, wires, and coils. And a K&N Intake. Now for the dillemna. It doesnt want to idle. If I disconnect a vacuum line from the intake plenum, it idles fine right at 750. For obvious reasons this isnt good because air is entering the motor without being read by the MAF. I have checked the computer for codes and it has none. It seems to drive fine, however under load over 3000 rpms it wants to miss. I assume from the vacuum leak? Any ideas? If I plug the vacuum line up I need to hold the throttle open roughly an 1/8 inch or so. If I reset the base idle and the TPS sensor would this be a reasonable cure? Id like to get my motor running properly before i make my trip to WSU at the end of the month for orientation. Thanks for the help!

mjr46

try base idle reset to start with

FordxFour

Tried the base idle reset and made sure the TPS voltage was in spec and still the same problem. I have another question that may answer this problem. How do you know which MAF sensor you need? When I went to schucks to buy a new one, they offered three different kinds for the same 1993 Mustang HO. I tried one and it gave a code saying voltage was too high so i tried another one and it gave me no codes. However I dont know if that was the right problem.

Venomantidote95

IAC isn't functioning properly its a controlled vac leak. U removed a small line ex: fpr line and it idles fine?