1994 mustang ecm running rich

R8ge · Jul 23, 2019

***MAYBE SOLUTION 7 months after install and slowly replacing sensors I got left with the bap/ map that’s by open air. No code and was thrown on it but when I checked it’s votage output on an 80 degree day it was 1.3 volts and jumped to 2.52 and held steady. It should have been 5 volts because I’m only 300 ft above sea level.

I have a truck but it’s part mustang so that’s why I’m here. It’s a 460 converted to maf running a tm40 ecm. The only fualt codes I have are 137 and 173 which are rich mixture bank 1 and rich bank 2. I have replaced every sensor but map. Even ones I didn’t have codes for. I did have a lean code on bank 1 replaced injectors because code wasn’t consistent and got rich both banks kind of good. Stock injectors are 24 lbs and that’s what I went back with. My mileage is in the ter was 12 on speed density. 11 on maf and 7.4 on new injectors. Truck runs perfect no idle issues no cruising issues no wot issues. Just terrible gas mileage. The check engine flashes intermittent I also have a cai. Timing is 10, sparkplugs are new, wires are new and separated, coils new. Vaccume is 19psi at idle no oil consumption. When doing cylinder balance test pcm says 5 is bad. Plugs look good and no oil fouling ect.
****O2 sensors bank 1 is 40 inches away from collector on manifold and bank 2 is 20 inches away from manifold. Could be issue.
**** The positive crank case vent goes to open air and not the intake. Just thought to throw this in there.

Noobz347 · Jul 24, 2019

R8ge said:
Stock injectors are 24 lbs and that’s what I went back with.

R8ge said:
tm40 ecm

I could not say for certain that this is the correct combination but there are others here who can. Maybe @Mustang5L5 or @jrichker

I would normally send you directly to the Surging Idle Checklist but I'd also like to know more about the combo you're using.... Intake, acc drive, any other combo info.

You can find the Surging Idle Checklist in here: https://www.stangnet.com/mustang-forums/threads/technical-thread-how-to-index.808661/

There are probably a few other items in that list you will find useful. The Surging Idle Checklist is under the Troubleshooting sub-heading.

Mustang5L5 · Jul 24, 2019

TM40 ECM and matching 70mm MAF (both from 94-95 GT Mustang) should be run with 19 pound injectors, not 24's.

Also, you mentioned a MAP sensor. When converted to mass air, the sensor vac port needs to be unplugged allowing it to sample atmospheric pressure. It's now a BAP sensor.

Noobz347 · Jul 24, 2019

Mustang5L5 said:
TM40 ECM and matching 70mm MAF (both from 94-95 GT Mustang) should be run with 19 pound injectors, not 24's.

Also, you mentioned a MAP sensor. When converted to mass air, the sensor vac port needs to be unplugged allowing it to sample atmospheric pressure. It's now a BAP sensor.

...and what's the number on the Cobra EEC that [is] setup for 24s? X3Z... something something...

Mustang5L5 · Jul 24, 2019

Noobz347 said:
...and what's the number on the Cobra EEC that [is] setup for 24s? X3Z... something something...

Depends on what he needs. He's running an SN95 ECU which means he should have an SN95 harness as well.

He would need a J4J1 ECU from a 94-95 cobra.

Or he could repin for a fox ECU and run the X3Z ECU from a 93 cobra.

Actually...this is a very good question to ask, but what wiring is being used on that engine to run the TM50 ECU?

Noobz347 · Jul 24, 2019

Mustang5L5 said:
Depends on what he needs. He's running an SN95 ECU which means he should have an SN95 harness as well.

He would need a J4J1 ECU from a 94-95 cobra.

Or he could repin for a fox ECU and run the X3Z ECU from a 93 cobra.

Actually...this is a very good question to ask, but what wiring is being used on that engine to run the TM50 ECU?

Seriously man... You're a walking Mustang encyclopedia

R8ge · Jul 24, 2019

Mustang5L5 said:
Depends on what he needs. He's running an SN95 ECU which means he should have an SN95 harness as well.

He would need a J4J1 ECU from a 94-95 cobra.

Or he could repin for a fox ECU and run the X3Z ECU from a 93 cobra.

Actually...this is a very good question to ask, but what wiring is being used on that engine to run the TM50 ECU?

I have redone the wiring an pin layout based upon what fiveology racing said. I bought the kit from them. I will Quote Brian thier tech guy. “The maf housing is an 80mm and it is fooling the stock 94 mustang maf sensor to think it’s running 19s”. This statement troubled me and leads back to me not wanting a tune but ending up getting one anyway. Me being out 1000$ for the kit with cai and me being out 750$ for the tune plus 300$ in matinence parts from the new ecm telling me hat was broken vs the old one that didn’t.

**sorry for late response also a mustang specialist is doing my tune and it is getting scheduled tommorow for sometime next week.

R8ge · Jul 24, 2019

Noobz347 said:
I could not say for certain that this is the correct combination but there are others here who can. Maybe @Mustang5L5 or @jrichker

I would normally send you directly to the Surging Idle Checklist but I'd also like to know more about the combo you're using.... Intake, acc drive, any other combo info.

You can find the Surging Idle Checklist in here: https://www.stangnet.com/mustang-forums/threads/technical-thread-how-to-index.808661/

There are probably a few other items in that list you will find useful. The Surging Idle Checklist is under the Troubleshooting sub-heading.

I have also done surging idle checklist idle doesn’t surge it’s actually smooth. Also it’s a 94 f350 460 converted to maf wires are added in overlay harness for each injector and o2 plug was added along with maf plug. I posted a picture of intake.

a91what · Jul 24, 2019

750 for a tune.... I am not charging enough

R8ge · Jul 24, 2019

a91what said:
750 for a tune.... I am not charging enough

That includes the chip it’s 400$ for custom tune.

R8ge · Jul 24, 2019

GUYS I EDITED POST BUT WILL SAY IT HERE CHECK MAP SESNSOR OUTPUT AND WAS 2.52 VOLTS AT 0 vaccume on a 80 degree day. It should have been 5 because I’m at 300 feet above sea level not 10,000 lmao

R8ge · Aug 4, 2019

I maf swapped a 460 with a 94 5.0 ecm. When I added the left o2 sensor I had to place it pipe distance wise 20 inches more pipe away than the right one was. The y pipe around trans makes it longer distance. I have an intermittent check engine light being rich left bank and the left o2 is the one farther away. Check engine light will come on at low rpm speeds or light throttle. Could the o2 cool off and cause it to pop open loop. I was told o2 distance didn’t matter but I think it’s been the thorn in my side for 7 months. Sometimes it will throw a right bank rich but the first code after ecm reset is always rich left bank. Trying not to have to get the truck tuned and waste 750$.

jozsefsz · Aug 5, 2019

My O2's are in my turbo downpipe and they're a significant distance away from the header (and through a turbine) and they do just fine. The distance could make it too cool to read properly but I don't think it would cause a rich reading. Since it's varying from left to right, even though one is first or last, I'd guess you might actually be running too rich for the computer to compensate once in a while. If you have an adjustable fuel pressure regulator, you could drop the pressure a bit and see what happens. You could also try swapping the O2 sensors from left-to-right and see if the first one follows your sensors - could be they have been fouled. You might also have an injector or two sticking and causing problems or maybe even a coil / plug / wire issue - you could run the cylinder-balance-test self-test and see if it tells you any of your cylinders are worse off than the rest to at least help pinpoint. If it only happens when it's damp outside for example, it's often the ignition.

R8ge · Aug 5, 2019

jozsefsz said:
My O2's are in my turbo downpipe and they're a significant distance away from the header (and through a turbine) and they do just fine. The distance could make it too cool to read properly but I don't think it would cause a rich reading. Since it's varying from left to right, even though one is first or last, I'd guess you might actually be running too rich for the computer to compensate once in a while. If you have an adjustable fuel pressure regulator, you could drop the pressure a bit and see what happens. You could also try swapping the O2 sensors from left-to-right and see if the first one follows your sensors - could be they have been fouled. You might also have an injector or two sticking and causing problems or maybe even a coil / plug / wire issue - you could run the cylinder-balance-test self-test and see if it tells you any of your cylinders are worse off than the rest to at least help pinpoint. If it only happens when it's damp outside for example, it's often the ignition.

Cylinder balance said 5 was bad but I have all new injectors and the injector is firing and the plug isn’t founded. The code does follow the bank not the sensor. I’m getting it tuned now as moving o2 helped just not much. Still occasionally rich. As it’s a 7.5 on a 5.0 computer things are wonky although they should have worked but I’m going to hopefully have a tuner straighten it out. Just money I was hopefully looking not to spend.

jozsefsz · Aug 6, 2019

Understandable. It's not unusual to get a bad fuel injector brand new unfortunately, especially those 'Bosch' Green Giants found all over eBay. Understanding it's a hassle, I'd consider moving the injector from one spot to another and see if the balance test failure moves with it. If you have it tuned before it's mechanically perfect, it'll really be money not-well-spent.

R8ge · Aug 6, 2019

jozsefsz said:
Understandable. It's not unusual to get a bad fuel injector brand new unfortunately, especially those 'Bosch' Green Giants found all over eBay. Understanding it's a hassle, I'd consider moving the injector from one spot to another and see if the balance test failure moves with it. If you have it tuned before it's mechanically perfect, it'll really be money not-well-spent.

Honestly I will tell the shop to do it as they do mechanic work and test it. If it turns out to be injectors then I only loose $149 on injectors.

R8ge · Aug 29, 2019

I have a 1994 gt ecm used in fiveology racing’s maf swap kit for a ford 460. The truck has a maf with cai dual 3 inch exhaust no crossover pipe and that’s all that’s done to it. So I had issues with injectors and such but I got rid of all cylinder balance test failures and am left with rich codes from both banks. Looking for someone who would know more about the ecms. When the truck starts it will SOMETIMES run like it’s cammed 15psi of vacuum. Wait 20 seconds vacuum shots up to 20psi runs fine except for rich codes.
The issue I’m having is why it’s running rich while driving as everything is functioning. It’s mostly at constant throttle positions and it’s bothering me cause I have 8 mpg down from the average 10.5-11. Sometimes when the ecm is reset it will learn the motor And get good mileage while other times it won’t learn the motor and get 8. I’m trying to not have to take it to a tuner to work on it but it’s looking like I will have to. Although it appears the ecm doesn’t like the 10 timing my trucks set and wants higher as it’s detonating the fuel in the half in the exhaust not in the piston chamber will it hurt to bump timing and see if it fixes it.

General karthief · Aug 30, 2019

Thread Merge Point

I merged your threads together here for a few reasons
this is one of many issues you have with this truck
it has followers already that may be familiar with what's been done already
it uses a computer from a 94-5 mustang V8 in a truck with a 460 ci in it.
and if that is not confusing enough, you're on a mustang site.

RioRed95Cobra · Aug 30, 2019

jozsefsz said:
Understandable. It's not unusual to get a bad fuel injector brand new unfortunately, especially those 'Bosch' Green Giants found all over eBay. Understanding it's a hassle, I'd consider moving the injector from one spot to another and see if the balance test failure moves with it. If you have it tuned before it's mechanically perfect, it'll really be money not-well-spent.

Had 2 sets of "green 42's" go bad on me. Currently using black 60's from a knockoff ebay place.. haha.. but they are working!

For the people reading this.. never skip on your fuel system. Thank me later. Go spend the $350 on those real siemens deka 60's. kk bye

R8ge · Aug 30, 2019

RioRed95Cobra said:
Had 2 sets of "green 42's" go bad on me. Currently using black 60's from a knockoff ebay place.. haha.. but they are working!

For the people reading this.. never skip on your fuel system. Thank me later. Go spend the $350 on those real siemens deka 60's. kk bye

The cheap injectors have ty Pintle caps that will fall off and that was only issue I had and fixed that and misfire gone.

1994 mustang ecm running rich

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