Stock 89 GT with T5 Trans...A9L or A9P?

[Mikey1968]

If you had a stock 89 GT with the T5 transmission and also had both the A9L and A9P computers sitting on the bench. Which would you use?

 

[2000xp8]

Realistically it doesn't matter.
My buddy tested it at the track way back (like 20 years), and the auto computer came out .02 quicker.

 

[90stang5speed]

I agree. it really wouldnt matter. The A9P has a little more timing advance from what I understand but, you can tune either one to do what you want with either something like the TWEECER RT or with a chip.

 

[HISSIN50]

Unless one wants to modify wiring, it might be wise to use the puter that matches the wiring in the vehicle. E.g., if it's a factory 5 speed car, use the A9L.

 

[Mustang5L5]

+1

Use the a9L. Using the auto computer will require a repin of the o2 harness which is not hard to do

 

[Mikey1968]

REPIN THE O2? Hmmmmm.....might explain my bad mileage....I have both computers and installed the A9P back when I was troubleshooting an intermittent cut out......ended up being the wires in the tank to the fuel pump. Wonder if it would cause a slight mid-range power-loss....very slight with very minor vibration.....not as smooth as my 86 5.0L Capri for a mid-range pull. Guess I can swap in the A9L this weekend.............Thanks! Keep the comments coming! It's helping!

 

[f8tlfiveo]

I have an a9p in my 88 5 spd converted from speed density. I didnt change any o2 sensor wires.. Runs fine...

 

[Mikey1968]

You sure you gotta repin the O2? I am not throwing any O2 codes..........?????

 

[Mustang5L5]

You sure you gotta repin the O2? I am not throwing any O2 codes..........?????

Has nothing to do with the O2 sensors.

Ford ran the neutral sensing circuit through the o2 harness for some reasons. Prob is depending on the transmission, the sig rtn wire is pinned differently and could potential fry the EEC.

Read this and interpret however you'd like

Oxygen sensor Harnesses - Manual/Auto differences and year differences - Ford Mustang Forums : Corral.net Mustang Forum

 

[No.11]

so I'm ok then? my car was aod an converted to 5spd. pretty sure a9p still on there. nothing else needs changing to get it working straight?

 

[Mikey1968]

Oh, gotcha! Been running the A9P for a year or so. Must be OK then.

 

[Mustang5L5]

If you want to make sure, unplug your EEC. Pull the coil wire and crank the engine. Measure voltage on pin 46 to ground. If you get voltage...swapp the pin on the o2 harness