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Discussion Starter #1
My wife has a 97 5.0/4R70W Explorer and the torque convertor is not locking up. The odd thing is that the check engine light is not on and the O/D light is not flashing. What is the best way to go about diagnosing/ fixing this?
 

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Get a scanner capable of powertrain data not just codes.
Alan
This may be a stupid thought, but does the CEL work (bulb good)? Does it come on when you turn the key before you start the engine?

When is the last time you serviced the tranny?

Any good automotive shop should have the scanner DD is referring to.
 

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Discussion Starter #4
OK, some more info: I bought the truck with transfer case problems and didn't really drive it much. I had a 98 V6 Mustang sitting at work with blown heads.
So I took the complete valve body and wiring harness from the 97 AWD transmission and put it in the 98 transmission before putting it in with a regular 2wd driveshaft.
I don't know if there was a problem with lock-up on either of these transmissions before or not. Could it have anything to do with swapping the 97 v/b onto the 98 case?
 

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Discussion Starter #6
OK, I scanned it with a Snan-on Soltice this evening. It was showing comand for 100% lock-up, but when watching engine RPM and output shaft RPM there was no change. So it is likely either the solinoid, or the convertor. Or maybe a blocked passage way.
Any ideas?
 

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OK, I scanned it with a Snan-on Soltice this evening. It was showing comand for 100% lock-up, but when watching engine RPM and output shaft RPM there was no change. So it is likely either the solinoid, or the convertor. Or maybe a blocked passage way.
Any ideas?
I'd pull the pan and take a look first. I've also read improper line pressure can cause this problem (too low or high).

Lock-Up Solenoid:


Down near the bottom of the page:
http://www.tccoa.com/articles/mn12-techinfo/trans-tech/4r70w_rebuild.html
 

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Check the lockup solenoid, then the tcc regulator valve and if none of them scream a problem check the pressure regulator valve. It wouldn't hurt to upgrade the pressure regulator valve anyway. There is the possibility that something else in the transmission such as the overdrive band is slipping and when the load of lockup is added it becomes obvious.
Alan
 

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Discussion Starter #9
Thanks for y'alls help. So it is doubtfull it's the convertor? I guess I will J-mod the 98 Mustang V/B and try it before i snatch the tranny for a converter swap.

I am doubting the O/D band to be a problem because there is no lock-up in 3rd either.

I have very little history on this V6 Mustang transmission other than it only had 104k miles. The fluid looked/smelled good and had been changed before (no mushroom in the pan). But knowing the people it came from, I doubt they put the V fluid in it though.
It does have fresh Valvoline V fluid in it now.
 

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Discussion Starter #11
I j-mod'd the 98 Mustang V/B and put it in today along with its lock-up solinoid. I used the 97 Explorer shift solinoids.
The great news is, IT WORKS! Lock-up and all.

The Explorer V/B did shift better in my opinion, but at least I feel safe for the wife to drive it now.

Thanks Alan, and NetKeym for the help.
 

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I j-mod'd the 98 Mustang V/B and put it in today along with its lock-up solinoid. I used the 97 Explorer shift solinoids.
The great news is, IT WORKS! Lock-up and all.

The Explorer V/B did shift better in my opinion, but at least I feel safe for the wife to drive it now.

Thanks Alan, and NetKeym for the help.
You're welcome. That's interesting that a 1997 Explorer 5.0L valve body shifted better than the 1998 Mustang one.

Alan, do you have any input why that would seem the case? Especially with the j-mod and everything. Could this be something like the issue I ran into with mismatching a 1994 ECM to 1995 Tranny with the vb programming?
 

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Discussion Starter #14 (Edited)
The 1-2 and the 2-3 shifts are about the same. At 80% and below throttle the Explorer V/B felt better (cleaner). At WOT the Mustang V/B's 1-2 and the 2-3 are slightly better, but I not by alot. 3-4 is sloppy now. The most noticeable improvement is the downshifts are faster and firmer.

I was expecting alittle bit firmer shifts, especially at WOT. For a comparison it is about like a stock Honda now, other than the lazy 3-4. Actually, other than my 99 P71's great 3-4, it feels like it did stock before I pulled the 1-2 and 2-3 lower springs.
I should have started with a 99-00 P71 valve body I think.
 

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Now for clarification, this is a V6 Mustang v/b, not a V8. That is likely a difference.
You can always take it apart again and drill the holes bigger to the next level as described in Jerry's thesis.

I plan on that next time I service my tranny.
 

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Discussion Starter #18
If/when it comes back out it will be to get a j-mod'd P71 V/B. The 3-4 is SOOO weak now, and I wouldn't want to fool with this V6 V/B again.
 

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I wouldn't do that, there is probably something wrong. When you drop the pan to service it put a sonnax pressure regulator valve, check the 3-4 valves for wear or broken springs etc.. as well.
Alan
 
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