Trans Disengages at 5200 RPM in Third - TCCoA Forums
 
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post #1 of 9 (permalink) Old 08-01-2011, 05:01 AM Thread Starter
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Trans Disengages at 5200 RPM in Third

Back in 2003 before I read about the J-Mod, I had to get my trans rebuilt. I bought this "Interceptor" kit off the Internet and my uncle installed it. It has been going strong ever since even through some track abuse. When I got the BOC e-mail tune, the 1-2 shift became extremely hard due to the mix of mechanical + pressure increase via tune. I got that problem resolved through dyno tuning.

One problem that my tuner could not fix was that the transmission loses its lock in 3rd gear ~5200 RPM. Every single time without fail, once it gets to 5200 RPM, the engine revs like mis-shifting a manual trans and I have to let off. It does not occur in 1st or 2nd, only 3rd. The tuner thinks it's a mechanical issue like clutches slipping, but it still shifts perfectly and there are no slipping issues anywhere else even under WOT. He says the torque converter is programmed to remain locked.

Has anyone else had this sort of problem and know of a resolution? Or even an educated guess? Could it a be a fluid pressure issue at that RPM and load? Is it trying to shift to 4th/OD? A known weakness in the '95 trans that there is already a fix for? I don't know.

- Rebuilt '95 4R70W trans going on about 8 years
- B&M trans fluid cooler
- 3.73 track-loc
- '04 Marauder torque converter

I'm already there, but as power increases even more, I am going to need 3rd gear to hold all the way to redline with those gears or I'll be getting clipped at the traps against slower cars.

I come from a dusty place.
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post #2 of 9 (permalink) Old 08-01-2011, 01:17 PM
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My cougar had the same issue.
It was like trying to catch a ghost.
In third gear the trans. (according to the transmission shop who worked on it here) would down shift to second gear.
This would cause the RPM's to act like it was out of gear.
The transmission cannot down shift to second gear at that RPM, so it just freewheels. Cost a lot of cash to find this out. A lot of parts were changes and checked as well.
I had a stand alone transmission controller installed, this solver the problem.
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post #3 of 9 (permalink) Old 08-01-2011, 02:55 PM
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Same thing happened to me when I was experimenting with different shift schedules with PRP. The one that caused it was a slightly tweaked Marauder shift schedule. My unaltered RPM based shifts were 5200ish and after the 2-3 shift it would nearly overrev once it got around 4500 at 80mph. It turned out the Mauraders higher WOT 3-2 downshift curve was being crossed right at that speed in 3rd.

-Matt
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post #4 of 9 (permalink) Old 08-02-2011, 01:05 AM Thread Starter
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Thanks guys, for the replies. So it looks like the problem lies completely in the shift tables and the properties of the Marauder TC. I don't recall if I last received a tune file from Lonnie before or after I got the TC, but yeah I'll talk to the dyno tuner about focusing there. Sorry you wound up spending so much cash, r429460, but glad you were able to solve the mystery. Much appreciated.

I come from a dusty place.
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post #5 of 9 (permalink) Old 02-20-2016, 01:43 PM Thread Starter
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Just for the record, this problem turned out to be in the tune. It's been awhile, but it had something to do with the tuner using the wrong code for the EEC or VIN, and once they discovered the problem they were able to correct it. I can now rap out 3rd gear to the rev limiter and it felt awesome having that back! This didn't get corrected until the shop worked with the legendary RobertP when my OD finally went out on my previous trans, i.e. the one mentioned in the OP.

Looking back, I don't think the problem existed before I let the tuner take over those duties. It's just a shame that it took the dyno tuner a couple years to discover what Lonnie Doll probably knew all along in his e-mail tunes. I even took it to Murillo MotorSports to get retuned and get that fixed, but they didn't even address the problem.

The car now has a 4R70W from Rob's Tire and Auto and a ~3200 stall convertor from Circle-D. The problem I have now, or rather 2 years ago before I took the car in for paint, is that the convertor locks up too fast in 2nd gear below my power band and therefore hurts performance significantly. The tune was meant for a much more torquey and powerful engine, such as the one in a certain 9-sec boosted MN-12 lol

I come from a dusty place.

Last edited by 4point6r0x0rz; 02-20-2016 at 01:54 PM.
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post #6 of 9 (permalink) Old 02-21-2016, 09:02 PM
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Good to hear. I have the same issue in my bird only happens around 4200 rpms? I think.. It really sucks when trying to pass someone at high speeds. I posted a vid a while back of it doing it at WOT. I've yet to have it fixed.

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post #7 of 9 (permalink) Old 02-21-2016, 09:05 PM
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post #8 of 9 (permalink) Old 02-22-2016, 08:32 AM
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Yaaaasssss... sucks. The tbird has a list building up.. She's kinda been on the back burner while I save up for a new daily. Happy birthday btw

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post #9 of 9 (permalink) Old 02-22-2016, 05:59 PM
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Quote:
Originally Posted by Tbird1997 View Post
Yaaaasssss... sucks. The tbird has a list building up.. She's kinda been on the back burner while I save up for a new daily. Happy birthday btw
I can tell you a few things, based on my experience:

It won't shift 2-3 or 3-4 at wot.

Except: at 127mph it will do the 3-4; we have the PRP fix for that now.

Shift schedule is highly dependent on throttle position.

Many other issues I won't go into.


Way better tunes are available.

Call Don Lasota; I don't know if he still checks don96vert for PM's...
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Black '96 Cougar XR-7 (Lazarus) 210k mi PI Intake, '02 4R70W, Jmod, PST DS, GrogTune, Konis, Mark LCA+Poly, racecougar Custom Engine Chain, and JL and racecougar Bracing.
Black '97 Tbird Limited Edition, '02 4R70W, 255 walbro, PST DS, PBR Brakes&SS lines, Toicko Blues & Springs, GrogTune.


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