A9P or A9L Which is better?

phantomxdino · Jan 4, 2011

ok so i have an 88 fox with a stock 302, this winter im putting a e303 cam, 24lbs injectors with a calibrated maf, and have a edelbrock performer intake with a 65mm throttle body and spacer for it. I am also doing a maf converstion with a wiring harness and A9P computer out of a 92, but have done research and cant figure out which is a better computer to run the A9P or the A9L. Multiple sites say one is better than the other.

Mustang5L5 · Jan 4, 2011

The differences are negligible. You'd never notice a difference.

A9L is 5-spd
A9P is AOD

Get the EEC that corresponds to the tran you have in your car

1992 wiring harness will not work with 1988 body harness. The connections inside differ. The only interchangeable harness is out of a 1988-1989 car. A standalone aftermarket harness will be much easier and allow you to correctly tap the fuel pump and vss on the car

http://www.mass-air.com/Products.htm

BYRDPE · Jan 4, 2011

i did the aod to t5 swap and i am using the a9p that came in my 92. i have read that the a9p is a tad more aggressive because of the aod torque converter or something along those lines. i dunno...can't see how you could go wrong with either. you'll probably end up either getting a tune or using a tuning solution so it will be partcially negated anyway.

1988WHTGT · Jan 5, 2011

I've had both in my 88 GT that I converted. Only difference I noticed is that when I put it in gear with the A9P (I have a 5 speed) my RPM's jump up a little. I don't know if thats normal or not, ha.

HISSIN50 · Jan 5, 2011

The P does have more off-idle timing (to accommodate the converter).

I agree with using one for the style of trans you have (assuming it's not a converted car) so you need not worry about any repinning.

Mustang5L5 · Jan 5, 2011

HISSIN50 said:
I agree with using one for the style of trans you have (assuming it's not a converted car) so you need not worry about any repinning.

That was what i was kinda alluding to.

There are differences in how each is pinned to specific wiring in the vehicle...specifically the o2 harness and the NSS on the T-5. Why it's easiest to just stick with matching "original" OEM trans type to computer to avoid any issues with AOD to 5-spd swaps

phantomxdino · Jan 5, 2011

so my car is an original 5spd car but i have a tremec 3550 in it. the only reason i was gonna run the A9P is cause i got all the parts in a package deal. so the 89 wire harness is the only year that will match up to the 87-88 wiring?

Mustang5L5 · Jan 6, 2011

phantomxdino said:
so the 89 wire harness is the only year that will match up to the 87-88 wiring?

Yes

If you pop the pass kick panel off, you'll find the engine harness does not mate up with the body harness. They changed in 1990 with the addition of airbags and other wiring changes

liljoe07 · Jan 8, 2011

Mustang5L5 said:
That was what i was kinda alluding to.

There are differences in how each is pinned to specific wiring in the vehicle...specifically the o2 harness and the NSS on the T-5. Why it's easiest to just stick with matching "original" OEM trans type to computer to avoid any issues with AOD to 5-spd swaps

60 PIN connector is PIN'd exactly the same for both ECM's. You can stick and A9L in and Auto car and be just fine, and vise versa.

ECM choice per trans setup is irrelevent. Only negative effects come when you add a T-5 to and Pedal setup, to a factory Auto car. When you have that setup, you can fry either ECM. Neither is immune to getting fried.

capri debris · Jan 8, 2011

liljoe07 said:
60 PIN connector is PIN'd exactly the same for both ECM's. You can stick and A9L in and Auto car and be just fine, and vise versa.

ECM choice per trans setup is irrelevent. Only negative effects come when you add a T-5 to and Pedal setup, to a factory Auto car. When you have that setup, you can fry either ECM. Neither is immune to getting fried.

Dude, that is bad info right there.
I suggest you read through the link below before you tell anyone else the ECUs can be swapped without problems.
Oxygen sensor Harnesses - Manual/Auto differences and year differences - Corral.net : Ford Mustang Forums

This subject has been covered very well in that thread and even though it's long, it should be read by anyone who has the chance to.

In a nutshell, because of the different ways the 5spd and AOD cars have the O2s wired, you WILL fry the ECU if you have an originally AOD car and use an A9L.

If you have an originally 5spd car and use an A9P, it will work but not the best choice.

liljoe07 · Jan 8, 2011

capri debris said:
Dude, that is bad info right there.
I suggest you read through the link below before you tell anyone else the ECUs can be swapped without problems.
Oxygen sensor Harnesses - Manual/Auto differences and year differences - Corral.net : Ford Mustang Forums

This subject has been covered very well in that thread and even though it's long, it should be read by anyone who has the chance to.

In a nutshell, because of the different ways the 5spd and AOD cars have the O2s wired, you WILL fry the ECU if you have an originally AOD car and use an A9L.

If you have an originally 5spd car and use an A9P, it will work but not the best choice.

Dude, apparently you didnt read the thread. If you did, you would notice MY SCREEN NAME in the thread.

Once again, the 60 PIN connectors are PIN'd out the same. So whats different? The fact you change to a 5-speed setup, and use a clutch switch with the Auto 02 harness. Computer being used has nothing to do with it. You would fry and A9P with a 5 speed trans and clutch switch being used with an Auto 02 harness. Its completely unavoidable due to the 12v start signal being sent to PIN 30 through the Auto 02 harness.

I can break it down real good, and explain to a T. I promise you I know more about this subject than you. My info is far from being bad.

93lxtwin · Jan 8, 2011

Outstanding info in that link provided above. I read through the whole thing, and was educated on the T-5 swap issues that can arise. However, I am still trying to figure out specifically on my 93 lx, supposedly a factory AOD, when I purchased it, it had been converted to a 5 speed with an A3m computer. This computer fried about a month ago. I bought an A9l as a replacement, now I'm concerned I may fry this one if the swap wasn't done correctly before I bought the car. Gonna check my wire colors for the O2 jumper tomorrow using the pics provided in that link. Thanks again for posting that info, highly valuable!

liljoe07 · Jan 8, 2011

93lxtwin said:
Outstanding info in that link provided above. I read through the whole thing, and was educated on the T-5 swap issues that can arise. However, I am still trying to figure out specifically on my 93 lx, supposedly a factory AOD, when I purchased it, it had been converted to a 5 speed with an A3m computer. This computer fried about a month ago. I bought an A9l as a replacement, now I'm concerned I may fry this one if the swap wasn't done correctly before I bought the car. Gonna check my wire colors for the O2 jumper tomorrow using the pics provided in that link. Thanks again for posting that info, highly valuable!

Best way to remember what is safe concerning the loop wire on the 02 harness.

If the Looped wire on the 02 harness connects the yellow/purple to the white(or purple)/pink wire, that will fry any ECM when a 5 speed setup is used.

If you have blue/yellow looped to purple/yellow, you are just fine.

93lxtwin · Jan 8, 2011

Thanks again for that explaination. That makes it crystal clear for me now on what to look for tomorrow when I get a second. Curious to know how long would it take to fry and ECM, or could it vary? I'm just speculating right now because my car may have actually been properly converted and I just don't know it yet. Or maybe it hasn't been and it takes a little bit for it to fry the computer. When mine went, I drove the car to work, parked it like normal, worked all day, came out to go home, and nothing. No injector pulse, had fire, fuel pump and pressure, power to injectors, just no ground to pulse them. Finally traced to the ECM, when I pulled it out, it looked like it had been in a fire place. I'll be sure to check on the loop wires tomorrow to prevent that from happening again. Thanks again for all the insight to this subject. You guys are awesome!

capri debris · Jan 8, 2011

liljoe07 said:
Dude, apparently you didnt read the thread. If you did, you would notice MY SCREEN NAME in the thread.

Once again, the 60 PIN connectors are PIN'd out the same. So whats different? The fact you change to a 5-speed setup, and use a clutch switch with the Auto 02 harness. Computer being used has nothing to do with it. You would fry and A9P with a 5 speed trans and clutch switch being used with an Auto 02 harness. Its completely unavoidable due to the 12v start signal being sent to PIN 30 through the Auto 02 harness.

I can break it down real good, and explain to a T. I promise you I know more about this subject than you. My info is far from being bad.

Here is your post (#99) from the Corral thread...

"That is exactly how it is. The S terminal on the starter solenoid is where this ground is sourced from in a Auto setup. The manual ECM gets fried when using the Auto 02 harness because the S terminal has 12v when cranking. This is when the ECM fries. But when the key is not in crank, the S terminal is a ground."

That statement contradicts what you say in post #9 of this thread, because the ground source is different in the AOD O2 harness vs. the 5spd O2 harness.

Which is it?

Now tell me if you put an A9L into an AOD harnessed car it won't fry the ECU... because it WILL... due to the different sources of the ground.

So your advice that any ECU can be used in any car is flat out wrong.

__________________

liljoe07 · Jan 8, 2011

Doesn't contradict anything. You just don't understand the difference between the two post.

Post 99 is in reference to using a manual ecm with a CLUTCH SWITCH and auto 02 harness . The clutch switch is what sends the start voltage! So if you don't have a clutch how do fry an ecm from start voltage? You can't! So either ecm can be used on either set as long as the correct 02 harness is used for the trans being used.

The computer being used has zero to do with it! Zero,zilch,nada!

You don't have a complete understanding, yet you are arguing with someone that does?
Come back and try again tomorrow to prove me wrong. Maybe you will have better luck then. But I doubt it. Cause there is more I can explain.

capri debris · Jan 8, 2011

Why are you being such a dick?

All I was trying to do by quoting your post #9 in this thread was to keep people from getting confused and frying their ECU. The way you worded it could've been better.

This quote makes it clearer because you point out that the proper harness must be used to put in a different ECU.

liljoe07 said:
So either ecm can be used on either set as long as the correct 02 harness is used for the trans being used.

How many people change the harness when they switch from an AOD to stick or vice versa... not many. So if someone changed the tranny and leaves the original harness and reads your post (#9) and thinks they can use either ECU, bad things are gonna happen.

I just wanted to clear up the advice you gave since this is such a confusing subject (hence the long thread I posted from the corral).

My intention was not to insult you, but you seem to take great pleasure in insulting me.

You know nothing about me and what I know. I bought my first Capri when I was 18 and I'm now 45. I have owned a total of eight Capris over that time frame and currently own four Capris right now. I've done complete teardown restorations on these cars and have much knowledge of them.

I don't want to get into a pissing contest with you and I'm not questioning your knowledge, but at least humor me and view my website to see my latest restoration project and perhaps you will have a little more respect for me.
Capri Restoration Project - captocapri101's Photos

I try to be positive and helpful on the forums I visit and don't deserve to be treated like dirt by you or anyone. Sorry if I offended you by trying to clear up one of your posts so it didn't get mis-interpreted by someone who may not know what you and I know.

The whole idea is to help others on here, not insult fellow members like you insulted me.

peace.

larrym1961 · Jan 9, 2011

I have read all this with great interest. I converted my 87 AOD to a 5 speed about 8 years ago. Other than connecting the clutch Engage switch and interlock switch and the Reverse light and NSS jumper wires. I have done no other wiring. but I did retain the C3W auto computer. Until recently I switched to an A3M computer, which still works, then I swithced to an A9L since everybody seems to be using those. I have used it for several months now, and I can put a code reader on it and it will show code 11's. I am glad I read this post it may have saved me a computer or two as I have not done a thing with the O2 harness from the factory configuration. So I too will do the pin 46 test while cranking the engine with the ECU removed to verify no voltage to the pin. If there is I hope I have not damaged the computer yet but as of now the car runs fine other than the hanging idle issue. But after reading that informative post I see that not repinning the 02 harness can cause that also, and I have dealt with that issue every since I did the 5 speed conversion. So I thought switching to a 5 speed ECU would stop that, wrong!
Hey to you guys that have been there, done that thanks for the input and knowledge , You have answered Questions I have had for a long time! So what I am gathering is you really don't need to go out and find a 02 harnessfor a '93 Mustang 5 speed car, just re-pin the jumper wire like you would re-pin a wire @ the ECU connnector? or go out and find an 02 harrness? either way sounds simple enough to me.

capri debris · Jan 9, 2011

I'm glad if I helped you out. I don't think you need to worry about your ecu being hurt because as long as you can still pull codes, it should be fine. Even if you burnt it, it's not too hard to solder a jumper wire on the circuit board to fix it.

liljoe07 · Jan 9, 2011

capri debris said:
Why are you being such a dick?

You jumped on my information first, saying it was bad, and now Im the bad guy? Like I said, you didnt understand why it happens. So how do you know my info is bad?

All I was trying to do by quoting your post #9 in this thread was to keep people from getting confused and frying their ECU. The way you worded it could've been better.

So why not ask for clarification as to what I meant? Instead of telling me I was wrong two different times and telling me my information was contradicting. I only strung you along to see how long you would argue about something you had little knowledge about.

How many people change the harness when they switch from an AOD to stick or vice versa... not many. So if someone changed the tranny and leaves the original harness and reads your post (#9) and thinks they can use either ECU, bad things are gonna happen.

If they change to a 5speed setup,use the Clutch and NGS switch, and leave the Auto 02 harness, it doesnt matter what ECM they use, it will fry. It has nothing to do with what ECM is being used. Nothing at all.

My intention was not to insult you, but you seem to take great pleasure in insulting me.

Show me where I insulted you. Show me where I called you a name, I simply said you dont have an understanding.

You know nothing about me and what I know.

Youre right, I dont know everything you know. But I knew you didnt fully know about the subject at hand. If not then my first post in this thread wouldnt have been labled as bad info by you.

I don't want to get into a pissing contest with you and I'm not questioning your knowledge, but at least humor me and view my website to see my latest restoration project and perhaps you will have a little more respect for me.

What makes you think I dont respect you? You are a car guy just like me. You jumped on my post first. If i was correcting someone, I would make darn sure I fully knew what I was talking about.

I try to be positive and helpful on the forums I visit and don't deserve to be treated like dirt by you or anyone. Sorry if I offended you by trying to clear up one of your posts so it didn't get mis-interpreted by someone who may not know what you and I know.

You are taking things out of context. I never treated you like dirt, you were just hell bent on proving me wrong. So I had fun at your expense.

The whole idea is to help others on here, not insult fellow members like you insulted me.

Click to expand...

Insult? You questioning my knowledge on a subject I alone took the time to disect(on my own car) the reasons as to why it happens, and how it works to get a full understanding was the insult. I see no one else offering the correct information like I did. I know it from start to finish, because I did the leg work, so others had the correct information. Even fried an A9P on purpose to prove a point, stuck a A9L in and Auto car with no issues. Im not speaking from something I read on the internet.

Once again, show me where I insulted you?

And Im pretty sure I have helped many on these forums. Im know for a fact Ive had 14-15 ECMs sent to me for soldering, phone calls to forum members to help with issues. Never charged a dime for the ECM repairs, or for my time driving to post office to ship things out.

Click to expand...

A9P or A9L Which is better?

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