Timing Issue with A9P Swapped for A9L?

[Mikey1968]

Anyone swap in an A9P computer for a A9L? If so, did you get pinging in the mid-range under acceleration?

Stock 89 GT with T5 trans....I know the A9P pulls in +10 deg timing in midrange rpm and +1/2 deg at WOT over the A9L. I have a minor mid-range rattle that seems to lessen when I use premium gas in lieu of regular. Until I tried premium, I thought it was just the cats rattling on my 4 point k-member brace. Perhaps I'm wrong and need to recheck timing......if so, what's ideal timing for stock 89 5.0L HO?????

Thanks,
Mike

 

[87coupe50]

10*BTDC

"I know the A9P pulls in +10 deg timing in midrange rpm and +1/2 deg at WOT over the A9L"
Not sure where you got that info... dont think that's right, but dont have my tuning computer here to verify

 

[f8tlfiveo]

I have an a9p with a 5 spd and no problems with 12-14 degrees timing with 87 octane..

 

[HISSIN50]

The auto puter should have more timing off of idle (calibrated for the converter in an AOD car).

If you have doubts, I'd remove a couple degrees at a time till you're happy.

 

[stang&2Birds]

For timing, there's very little difference between the A9L and A9P.

Also see:
Mustang FAQ - Wiring & Engine Info

From:
View attachment 204882 Spark Advance Tables for the A9L, graphic by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/A9LSparkTables.gif

 

[vristang]

10*BTDC

"I know the A9P pulls in +10 deg timing in midrange rpm and +1/2 deg at WOT over the A9L"
Not sure where you got that info... dont think that's right, but dont have my tuning computer here to verify

http://tinyurl.com/Compare-A9L-A9P-X3ZCompare-A9L-A9P-X3Z

 

[Mikey1968]

http://tinyurl.com/Compare-A9L-A9P-X3ZCompare-A9L-A9P-X3Z

My bad, I mis-read and remembered incorrectly this comment on this exact post......My memory deleted the words "WOT"

notice that the A9P does add 10* of advance at lower WOT rpm's. If proper gearing is being selected by the driver, then a manual t5 Mustang should not see WOT below 1,600 rpm. For this reason using an A9P in a t5 Mustang will provide minimal performance gain due to ignition timing advance.


Anyway, premium seemed to help but it really shouldn't.....my base timing is around 11 deg.....maybe it's my creative imagination....I'll go back to 87 octane and see....