Just finished T5 swap now driving issues

fobra · Nov 30, 2012

I have a 1995 Mustang GT (AODE) that was recently swapped to a T5. The swap went smooth, but now I have some serious driveability issues.

The car shifts and drives fine now except a misfire/bucking/dead spot at around 4k rpm and 5800rpm and cruising in 5th at about 15% throttle between 1800-2300rpms.

I bought a used 1995 Cobra 5spd ECU and plugged it in and the car wont even drive. Feels like a spark plug wire or two are unplugged. No power and wont accelerate. So I bought a 1995 GT 5spd ECU and plugged it in and it does the same exact thing. The car will hold idle but it sounds like a radical cam (im stock internals). When I plug the Auto ECU back in the idle is fine and it drives but still with the other issues originally noted.

I have some stored ECU codes but they all relate to the auto transmission and when it was giving out.

Ive changed/checked all the parts below:
(1) New TPS sensor calibrated to specs
(2) New cap and rotor
(3) New motorcraft spark plugs gaped to .48-.50
(4) New motorcraft spak plug wires
(5) New fuel filter
(6) Checked fuel pressure which is a 37-40psi
(7) MSD iginition coil
(8) Timing set to 10degress (stock)
(9) New King Cobra clutch/new pressure plate/resurfaced flywheel
(10) Cleaned MAF
(11) Fresh tank of 93 Octane
(12) New ignition control module

Any help/suggestions would be appreciated

**** MODS - shorty headers, off road H pipe, flowmasters dumped. 4.10gears (stock everything else down to the paper air filter) ****

g36 monkey · Nov 30, 2012

I know a friend of mine had a similar issue when he swapped his out. I'll give him a call to see if I can find out!

rz5.0 · Nov 30, 2012

Did you swap out Trans harness

g36 monkey · Nov 30, 2012

I thought thats what he meant by the manual ECU.

If you didn't actually get the harness for the trans then that is probably the issue.

TheNatster513 · Nov 30, 2012

Check your maf to. It might not be running right because that is a Cobra ECU ang not a Gt. Gt would work better.

fobra · Nov 30, 2012

rz5.0 said:
Did you swap out Trans harness

Yes, I swapped in the manual transmission harness when I did the swap.

Im using a TM40 1995 GT 5spd ECU right now and its giving me all the horrible issues and makes it un-driveable. The factory AOD allows me to drive but with a few hiccups.

fobra · Nov 30, 2012

g36 monkey said:
I know a friend of mine had a similar issue when he swapped his out. I'll give him a call to see if I can find out!

Thanks! Let me know. I have asked so many of my other firneds that have swapped their fox's and sn's and no one can figure it out. I even took a few people for a ride and everyone seemed stumped

rz5.0 · Nov 30, 2012

With the aode ecc it's suppose to do that. But when you swap over to the gt is supposed to fix it.. The cobra ecc will not work cus it's got different settings on it.. I swapped mine and had 0 issues.

cobra clone 98 · Nov 30, 2012

i swap one out before and all i changed was the tranny and never had no issues. the only thing i have ever been told was the computers where different from a t5 to auto.. and then i have had some people say it doesnt matter..

fobra · Nov 30, 2012

Maybe my 5spd GT ECU is bad? Is there a way to test it or do I have to just find someone else with a 1996 GT 5 spd and plug mine it to see if its good

rz5.0 · Nov 30, 2012

Do you know any one else with a gt eec make sure it's a t4mo..

fobra · Dec 2, 2012

Yeah, I checked again and T4MO is what I have. I m reading a lot of fox write ups where they mention they have to use a 5spd oxygen sensor harness or the ECU will fry. I have looked all weekend online for 5spd oxygen sensor harness for sn95 and no one sells one specific to 5spd. This makes me believe that the harness is the same for auto and 5spd for sn95's

Raffaelli · Dec 2, 2012

On SN95s the only thing different (harness wise) is the manual to automaic trans harness. The square plug near the passenger side firewall.

If you did swap that, The T4M0 should plug and play. Where did you get it? I suspect its bad.
When I did an auto to manual swap, I did NOT swap out the trans harness or computer. I put the PNP switch in N and unbolted it from the tranny and ran it like that. The auto computer "dropped spark," best way I can describe it, at approx 4500 RPM too. Stumbled bad above it.

Swapped in a manual trans computer (t4M0) and trans harness and worked flawlessly.

Check for vaccum leaks too. My PCV hose came loose and made it sound like it was cammin. Crappy performance too. Its at the back of the intake near the trans bellhousing.

Hope it helps.

Raffaelli · Dec 2, 2012

And as a side note, I do have the T4M0 out of my car ill sell cheap. (LOL). I assure you its good. Car got an A9L.

fobra · Dec 3, 2012

Raffaelli said:
On SN95s the only thing different (harness wise) is the manual to automaic trans harness. The square plug near the passenger side firewall.

If you did swap that, The T4M0 should plug and play. Where did you get it? I suspect its bad.
When I did an auto to manual swap, I did NOT swap out the trans harness or computer. I put the PNP switch in N and unbolted it from the tranny and ran it like that. The auto computer "dropped spark," best way I can describe it, at approx 4500 RPM too. Stumbled bad above it.

Swapped in a manual trans computer (t4M0) and trans harness and worked flawlessly.

Check for vaccum leaks too. My PCV hose came loose and made it sound like it was cammin. Crappy performance too. Its at the back of the intake near the trans bellhousing.

Hope it helps.

Thanks for your advise Im going to check for vaccum leaks again this week. And I'll PM you on the ECU

fobra · Dec 7, 2012

Okkkkkayyyy.........found the problem. Raffaelli your the MAN!!!!!!!!

I did all the general maintenance as in my original post. Yesterday I warmed up the car and let it reach normal operating temperature.....got a can of carb cleaner and went to town spraying all the vacuum lines. Everytyhing seemed ok until I got to near the PCV grommet. As soon as I hit that with some spray the car wanted to die. I took out the grommet and saw that it was all dried up and cracked letting air come in.

I bought a new PCV grommet (Dorman #42327 $3.99) and a crank case breather filter (Dorman #47064).

The PCV grommet and PCV valve were easy to just pull out but, the crank case breather was all gunked up and stuck. I had to use a pick with a L shaped end and really tug and fight to get it out. When I finally pulled it out I could see it was all gunked up and completely brown and burnt. When installing the new parts the grommet felt loose in the lower intake manifold so I wrapped some electrical tape on the outside and it fits snug now. I also unbolted the IAC and cleaned it out real good with carb cleaner.

Guess what....as soon as I started the car I could tell it idled better and reved a lot smoother. So I got brave and installed the T4MO ECU again. This time to my surprise it idled fine and I took it out on a test drive.....SUCCESS!!!!! The car runs smooth, doesnt misfire at 4k rpms, no bucking/hestitation when cruising etc etc etc (problems on original post)

So long story short......check vaccuum was the Pain in the A** problem

Just in case some has the same problem I hope this helps out......

P.S. I used the T5 harness on the tranny and all sn95s have the same 02 oxygen harness unlike the foxbodies. So as long as you use a manual T5 harness the factory sn95 02 harness will work fine. If anyone tells you to use the AODE ECU with your 5spd swap they are CRAZY! Foxbody guys/girls can use the Auto ECU because AOD is not the same as AODE. The E is for electronic and the computer is giving info on where to shift and that cause major driving issues when you do a 5spd swap on a sn95. The AODE ECU cause misfires/bucking/hestitation/hanging idle between shifts......and now the T4MO solved all those issues.