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Discussion Starter #1 (Edited)
Just to let everyone know, I have managed to put a 94-95 Mustang GT manual tranny ECM (catch code T4M0) into my 93 T-Bird. The whole reason for doing this was so I would get better support for the Tweecer RT I just purchased. The P3M does have some base support but there just wasn't enough control based on that. Switching to the T4M0 allows a lot more changes. Since the two are almost identical there was a good chance it would work. I bought one and tried it and it does work.

There is a ton of various info on this swap so it would probably be easier for me to answer questions than to try and post every single thing I checked into.

Also, by no means am I saying that this is a better solution than what SCT offers. I just wanted the ability to data log as well as the ability to tune the car myself. I realize that there are some shortcomings with the Tweecer but I can accept that.

There are two things that are missing from the Mustang ECM. The ability to control the digital dash is gone and the ARC is gone.

If you are considering putting a 4R70W into your 91-93 MN12 then you would probably want to get the U4P0 ECM from the same model years Mustangs. It will control the 4R70W for you.

Here is the pinout chart:

 

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Jedi Master
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i'm curious about this...no known probs so far??? would you recommend this for just 93s or do you think it will work on 91-92s too??? how bout the ones that have done the m5r2 swap???
 

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Discussion Starter #3
mn12xr7 said:
i'm curious about this...no known probs so far??? would you recommend this for just 93s or do you think it will work on 91-92s too??? how bout the ones that have done the m5r2 swap???
No problems so far. This should work for 91-93's since they are all the same ECM. The key here is that you use a ECM from a 94-95 Mustang GT with a manual tranny so that it doesn't have provisions for the electronic trans controls. With your five speed it should work almost exactly like the Mustang. Keep in mind that one of the biggest concerns with the Mustang ECM is that it pulls timing during shifts on a manual because it senses the throttle change when you let up to shift. For me this wasn't an issue since I have an AOD and I would never let up to do that.

What catch code is your current ECM?
 

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Keep in mind that one of the biggest concerns with the Mustang ECM is that it pulls timing during shifts on a manual because it senses the throttle change when you let up to shift. For me this wasn't an issue since I have an AOD and I would never let up to do that.
There is no shift retard, the 94/95 Mustangs do not pull timing during, before or after a shift. This is total BS that people with no clue have put out and convinced others. I get this same request about once ever few weeks for someone wanting a chip to stop the shift retard that is not there.
 

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heh i know my EEC (L1C) doesn't pull timing during a shift.. it ADDS timing :) like 10-15 degrees..

but then again, when i push down on the clutch pedal, and it thinks it's in Nuetral in turn adding timing for better fuel economy at idle/neutral?? (heh well the EEC does believe it's still an auto after all :)) But i have no idea if it's that quick at adding it or not??
 

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heh i know my EEC (L1C) doesn't pull timing during a shift.. it ADDS timing like 10-15 degrees.. but then again, when i push down on the clutch pedal, and it thinks it's in Nuetral in turn adding timing for better fuel economy at idle/neutral?? (heh well the EEC does believe it's still an auto after all ) But i have no idea if it's that quick at adding it or not??
Drugs up in Canada must be really good this time of year. There is no way your EEC adds timing when you put in the clutch. There are no provisions at all for this in that processor. Timing is based on rpm in all the 5.0 processors from 93 on back. Only other things that affect it are ECT, ACT and BP. There are a couple of other things but there is NO magic switch in the transmission or on the clutch pedal that will add or retard the timing.
 

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Lonnie said:
Drugs up in Canada must be really good this time of year. There is no way your EEC adds timing when you put in the clutch. There are no provisions at all for this in that processor.
Well we are known for least some good drugs, namely the smoking kind :D but personally i do not touch that crap...

Ahh Sir Lonnie, Have we forgotten what a Auto EEC does being in `drive' or `park'?? :tongue:

Go to your '92 (?) start it up, hook up a timing lilght to it.. check the timing.. see where it's at... NOW Pull the Red/blue wire at the starter Silnoid on the fender.. check timing again (never mind watching the RPMS drop) and see that timing changed... :)

Well it did change with my L1C EEC.. RPMS dropped like 200 or so RPMs, and Timing dropped like 10-15 degrees..

I COULD retest this on my car.. but it's alot harder to do now it's a 5 spd :)
 

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91 XR7 said:
Go to your '92 (?) start it up, hook up a timing lilght to it.. check the timing.. see where it's at... NOW Pull the Red/blue wire at the starter Solenoid on the fender..
Strange, that shouldn't happen. The R/LB wire is used for PNP (park/neutral position input) on the pcm module on pin # 30.
 

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You apparently are bored and want to try and prove some point, what you are talking about is the Neutral Drive Input Switch or as some call it the Park Neutral Switch. This has nothing what so ever to do with pulling out timing while the vehicle is operating. The input from this is for cranking and starting strategy where it fixes the timing, opens the IAC, shuts off emission and sets the air fuel. It has nothing what so ever to do with anything else once the vehicle is started so why do you even bring it up? Unless someone wants to drive down the road and then turn their key to start there is no way what so ever that feature will ever cause the timing to be backed off. This includes the clutch input.

Like I said there is no shift retard in any of the EEC IV 5.0 vehicles.
 

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Discussion Starter #11
Lonnie said:
There is no shift retard, the 94/95 Mustangs do not pull timing during, before or after a shift. This is total BS that people with no clue have put out and convinced others. I get this same request about once ever few weeks for someone wanting a chip to stop the shift retard that is not there.
Ok, well, if that's the case then it's even better. I had read that it was seen during dyno pulls and that the timing was being retarded about 2 degrees at 2500 rpm during a shift.

Thanks for the info.
 

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Ok, well, if that's the case then it's even better. I had read that it was seen during dyno pulls and that the timing was being retarded about 2 degrees at 2500 rpm during a shift.
That had to be with an automatic trans then. The 94/95 Mustangs with the electronically controlled automatic have what is called a Torque Reduction. Any of the electronically controlled automatics will have the Torque Reduction. The EEC reduces torque going into the trans dependent of TP by reducing spark or shutting off fuel injectors. This can be turned off or reduced.
 

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Discussion Starter #13
Lonnie said:
That had to be with an automatic trans then. The 94/95 Mustangs with the electronically controlled automatic have what is called a Torque Reduction. Any of the electronically controlled automatics will have the Torque Reduction. The EEC reduces torque going into the trans dependent of TP by reducing spark or shutting off fuel injectors. This can be turned off or reduced.
Excellent. That's good to know too. Thanks for the tips Lonnie.
 

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How's that EEC swap working out for you ? I'm thinking about installing an AEM intended for the 94/95 Mustang 5.0 (with 3 bar MAP sensor) to replace the 91 5.0 Tbird processer and SCT chip I'm using now. What I have now is working okay..but we are unable to get rid of the EGR codes.

I'm assuming it should require the same changes you made to get the stock 94/95 processer to work because the AEM unit just replaces the stock computer.

David
 

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David Neibert said:
What I have now is working okay..but we are unable to get rid of the EGR codes.

I'm assuming it should require the same changes you made to get the stock 94/95 processer to work because the AEM unit just replaces the stock computer.

David
What..... what do you mean you can't get rid of the EGR codes. What's your processor code. With the L1C you shouldn't have any problems. Who did your program for you?

I've got someone that called me about 3 months ago that was able to use the AEM with his L1C after changes some of the pins around. I don't recall his name or number but he was running a twin turbo setup and the shop doing the build and tuning it needed some guidance. I haven't heard back from them since.
 

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Lonnie said:
What..... what do you mean you can't get rid of the EGR codes. What's your processor code. With the L1C you shouldn't have any problems. Who did your program for you?

I've got someone that called me about 3 months ago that was able to use the AEM with his L1C after changes some of the pins around. I don't recall his name or number but he was running a twin turbo setup and the shop doing the build and tuning it needed some guidance. I haven't heard back from them since.
Lonnie,

The processor is a E1X, the person tuning the car is Dave Dalke. He has tried doing all the usual things to delete the EGR but we are still getting codes and CELs. They don't seem to be affecting the way the car runs, but they are annoying.

The wiring harness and the processor came out of a 91 T-Bird LX w/5.0 AOD. Everything functioned fine while running the stock 5.0 motor, but after installing the new race motor, deleting the air pump, EGR and PVC systems to accomidate the turbo, we were unable to delete the EGR using the SCT chip.

He's going to be back in St. Louis in a few weeks to assist me with a supercharger upgrade on my 91 and to make a MAF location and size change on the turbo car and we will be re-tuning both cars at that time.

David
 

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I've, not had that problem with this very same processor. He may not have access to that particular parameter depending on what software he has.
 

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Discussion Starter #18
David,

The 94/95 Mustang GT ECM is working great for me. I am using the Tweecer RT software to do my tune (primarily because I can do realtime datalogging) and everything has worked great so far. I am using the LC-1 wideband O2 to monitor my AFR and am actually logging through the Tweecer software by way of the EGR leads. The car has been running very stable and the AFR is right where it should be.

I think there is better software out there than Tweecer (SCT, AEM) but they are either more expensive than what I want to afford or they don't offer the datalogging functions that I want.

Bottom line is that the 91-93 MN12's just don't have a ton of support for their ECM's. That's the only reason I chose to go down a different path. I trust Lonnie but I wanted to learn this myself and the Tweecer offered me a more affordable route to doing that.
 

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Discussion Starter #20
Steve Cougar 25th said:
What about an A9L computer from a fox body? Would that work, because I have one in stock...
I looked into that one and decided against it because it would require considerable wiring changes.

In the end, if you are going to use a tuner to modify the stock program, it doesn't really matter if you use the SN95 ECM. Change it to meet your needs and you'll be fine.
 
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