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jrichker

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Mar 10, 2000
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lowendmac.com
it wont run at all with the 137 fire order
It is time to replace the computer that won't run using the 1,3,7 firing order.

Computer & interchange information for 5.0 Mustang

Revised 16-Oct-2011 to add O2 sensor harness warnings

The Mass Air computers from 89-93 Mustangs are interchangeable with a few exceptions. Just be sure you use the MAF & MAF sensor from the same series computer. The auto transmission computers use a different start circuit than the manual computers. You can use an auto trans computer in a 5 speed car with no problems or changes. I have done it in my original 89 Mustang GT, and I know it works OK. I would recommend avoiding using a 5 speed computer in an auto trans car due to the possibility of damaging the computer’ internal signal ground circuitry.

The odd duck is the 93 Cobra computer, labeled X3Z which is internally calibrated for 24 lb injectors. Use the MAF & MAF sensor from the X3Z computer to avoid problems with the computer's internal calibration. Try and avoid the 93 Cobra computer if you can.

Some cautions about O2 Sensor harnesses need to be observed to avoid damage to the computer.
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.
See http://forums.corral.net/forums/general-mustang-tech/1094179-oxygen-sensor- harnesses-manual-auto-differences-year-differences.html for more O2 sensor wiring harness info

If you have a damaged computer with signal ground problems, see the pictures below for help finding and fixing the burnt computer trace.
hash-146a243133771eeba54f17b17d721b1f-jpg.jpg

The fix is some careful soldering of a small jumper wire across the burnt section of copper trace.
20160325_234845-jpg.553347


All the following are mass air unless they say Speed Density
8LD - MANUAL 88 5.0L Mustang Mass Air - California
8LF - Auto 88 5.0L Mustang Mass Air- California
8LG - Auto 88 5.0L Mustang Mass Air- California
A9L - 89-93 5.0L Mustang 5-spd Mass Air
A3M - 93 5.0L Mustang 5-spd Mass Air
A3M1 - 93 5.0L Mustang 5-spd Mass Air
X3Z - 93 5.0L Cobra 5-spd Mass Air internally calibrated for 24 lb injector
A9P - 89-93 5.0L Mustang Auto Mass Air
A9S - 88 5.0L Mustang California Mass Air
C3W - 89-93 5.0L Mustang Auto
DA1 - 87 5.0L Mustang 5-spd Speed Density
J4J1 - 94-95 5.0L SVT Cobra 5-spd
T4M0 - 94-95 5.0L GT Vert 5-spd
U4P0 - 94-95 5.0L GT Auto
W4H0 - 94-95 5.0L GT
ZA0 - 95 Cobra R
D9S - 88 Lincoln LSC Speed Density
 

HemiRick

I'd be looking at jacking under the house
Jun 28, 2020
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Have you checked fuel pressure? My Mustang ran like that when mine was dying.
 
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AydenTv

Member
Nov 19, 2020
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update...
Car Kinda got worse each day now cant drive it too far at all without having to cut it off then recrank it .. then runs fine.. finally pulled codes.. got low tps (previous orwner fr drilled it out alot!!!...) and ACT or something 64 and 63 is what i got.. now i changed fuel filter earlier.. noticed brownish gas.. smh.. prob just need to dump tank put new gas in, and adjust tps and do a base idle reset.. only ptob is im poor, have no multi meter.. and it legit has almost a full tank (work on it daily almost and just drive it maybe 3 or 4 miles.. have had it since september 20th, only drive it back about 50 miles, and ive put like 130 miles on it since.. 50 since i last filled it..
 

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Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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An a9p should not run a 5.0 with the non-Ho firing order. The injectors are fired in the same order as the firing order. So something is off here.
 

AydenTv

Member
Nov 19, 2020
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Yeah google water in gasoline pics mine looks like that and here is a pic of what it is currently running lol also tps definitely needs to be messed with and a base idle reset for sure.. also maybe timing adjusted and then possibly going to pull wires and try the standard 137 fire order and pray this will fix my fox cuz if its the ecu like yall think... i know me, this thing is gonna sit under a tree, as i become one of those guys that got out smarted by the fox, and keep telling them kids its not for sell.. ill fix her one day.. lol when i goit the spout was missing (did not know at that time) and it came with a parts car.. been 3 months idk if i can go back and grab stuff now lol but first thing i grabbed was ecu and wire harness cuz i knew that be worth something.. paid guy drove 2 miles bucked and snatched but crunk up and did that till i finally got to a hwy and got up to 55mph.. did decent then still bucked and atched.. never touched tps but everyone fiddled withthat screw.. and fb group told me i didnt have a spout.. got it from other ecu.. so i swapped them out then saw no difference so swapped them back and sold it on ebay to a guy thay owns a foxbody shop lol he actually sent me videos back and forth and helped me with vac lines.. other than that i have drove it to the store back and forth and slowly narrowing down problems.. oh and it had like a half tank i think when i got car.. and was sitting in old guys garage for idk how long but gas prob wasnt the best.. filled it up on way back with medium gas 88 octane.. and dumped a fuel cleaner or 2 in it.. and i went 100 miles almost.. then filled it back up only took like 20 bucks.. and that was a month ago.. ive since became broke lol selling spare parts to buy this ponys love..
 

Potomus Pete

Gretchen Whitmer is eating at me
Mar 7, 2019
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There have been quite a few guys on here with bad gas. Needing new tank,pump,filter,ect. Could just be the gas. I would take a good size sample at the rail
 
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AydenTv

Member
Nov 19, 2020
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Alabama
Now I Have an 89 Foxbody 5.0.. its tps sensor has been just bored out bad.. so i decided to take it off and i find that not only is the green wire off but so is the orange constant power off.. tried to soldier it.. tape it.. and it just has been destoyed too much.. i have a 2000 mecury sable that is blown up been sitting for awhile and i saw its tps looked similar... ciukd i put it on my mustang if i cut wires and wired it up right.. im not a mechanic nor am i an electrician... i have a volt meter knife and tape.. what yall think google 2000 mercury sable tps sensor for pics..
 

TOOLOW91

If you're the village idiot what's that make me?
15 Year Member
Nov 29, 1999
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Now I Have an 89 Foxbody 5.0.. its tps sensor has been just bored out bad.. so i decided to take it off and i find that not only is the green wire off but so is the orange constant power off.. tried to soldier it.. tape it.. and it just has been destoyed too much.. i have a 2000 mecury sable that is blown up been sitting for awhile and i saw its tps looked similar... ciukd i put it on my mustang if i cut wires and wired it up right.. im not a mechanic nor am i an electrician... i have a volt meter knife and tape.. what yall think google 2000 mercury sable tps sensor for pics..
No that isn’t going to work . You need to fix things the right way like I told you on facebook.
 
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Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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You’d really have to verify the values the TPS is outputting are equivalent to a Mustang TPS. There’s a difference between working, and working properly.

what’s the voltage at idle, and the voltage at WOT?
 
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