Conflicting Stories On Using A9p For Mass Air Swap

I got a A9P in mine..... No problems here other than the rpm jump when you put it in gear.

I have an A9p in my car. Works great. However not to confuse you but my 88 was a factory Cali mass air car and was an AOD car which is now a T5 car. I've read the o2 sensor harness info on other threads. Do some research. You can burn the box up if you have the wrong o2 harness.

A9P with a 5 speed O2 harness works OK, I have done it with 2 different 89 5.0, 5 speed Mustangs.

Don't use an A9L with an auto trans O2 sensor harness without modifying the O2 sensor harness.


O2 Sensor harness interchange and modification

Originally Posted by 302EFI

Revised 16-Oct-2011 to add O2 sensor harness warnings
The wires for the 02's and low oil did not change throughout the years, they are all in the same place.
The main ones you need to worry about are (on the harness end (ECU) that plugs into the 02 plug) is:
\- 1. Lightblue / yellow
- 2. White / Purple
- 3. Purple / Yellow
The White/Purple & Purple/Yellow gets looped for a automatic ECU
The Purple/Yellow & Lightblue/Yellow for a manual ECU

See http://forums.corral.net/forums/gen...manual-auto-differences-year-differences.html for more O2 sensor wiring harness info

Basic premise to use with transmission swaps:
Only run a 5 speed trans O2 harness with an A9L. Do not run an Auto O2 sensor harness with an A9L. Doing so will damage the computer’s internal signal ground.
Only run an Auto trans O2 sensor harness with an A9P in a car that has an Auto trans. Using a 5 speed trans O2 sensor harness with an Auto trans will cause no crank problems. There has been some debate about this, but I will stick to what I have written until I see it in real life.

See http://www.stangnet.com/mustang-forums/749974-computer-issue.html#post7490537 for Joel5.0’s fix to the damaged computer internal signal ground.

90 model year harness only works with 90 model cars without inspection/rework.
The 4 cylinder O2 harness uses 4 wire O2 sensors. It probably won’t work correctly without modifying it.

i have an a9p in my 87 5 speed car. works fine.

i guess i should say that i also have an 89 engine harness and a 5 speed o2 harness from a 90 or so.