blk40th

whats the difference? i have both. which should i use?

FoxGT

a9p is the auto computer, a9l is the manual computer. You can use a9p on a manual aswell, I've hard you can't use the a9l on an auto though or you'll mess up your transmission.
I have an a9p in mine & everytime I start it it jumps up to about 1500rpm, then settles down to 800-900rpm then after about 20 seconds it settles down to 400rpm (i have an x303). Same when i'm coming up to a stop light or sign. It wont idle down to 400rpm unless i'm going slower than 10mph. The a9l just shoots straight down to idle. As far as I know both have the same tune though, just a difference in idle control. Might want to get a few more responses though before you decide, I could be wrong on some.
My friend just bought an a9p for a mass air swap on his '86 & I repinned his harness to accept the mass air meter so he wouldn't have to buy the $500 swap kit. His behaves the same as my car does. Before it used to idle differently, but it didn't have that pc.

blk40th

ok ty. i think thats why my car used to do the same thing. i had a fms piggyback mass air harness. but i bought an a9l and all new wiring, so i should be good to go. now i just have to sell all this extra stuff.

dudeboy

If you have both ecu's, then I would run the one for your trans type.

Performance wise there shouldn't be much difference.

stang8689

They go for atleast $100 on Ebay the A9L goes for more so sell the other

mjr46

a91 manual a9p auto.......spark advance is slightly diff for the auto but none the less you'll be fine.. they both perform well

Bullitt91

i have the a9p in mine and yes it can be used for both auto and man. i have noticed the idle difference when u start it.. it shoots up then settles down after a few seconds. but it runs like a raped ape!