That's correct. The only two speed sensors are the engine speed and vehicle speed. From those two sensors the ratio across the converter AND the transmission is calculated. It is impossible to separate the two. And it is only checked when the converter is locked and the trans is in fourth gear.

That's a new one on me. I have no idea how one would determine a slipping problem from a pressure test.

No, it would not.

If the converter is slipping to where it sets a slip code that can only happen when the converter is locked. The converter is not locked on a stall test, so it doesn't even look at what could be the problem.

It won't help your problem in any way, but it's easy to do.

Press the brake pedal as hard as you can with your left foot. Put the trans in gear. Press the accelerator pedal to the floor and read the maximum engine RPM. That's the output of the stall test. NOTE: DO NOT HOLD THIS FOR MORE THAN FIVE SECONDS AT A TIME. ALLOW AT LEAST 30 SECONDS IN NEUTRAL BEFORE DOING ANY OTHER STALL TEST.

 

Mark, are you saying that i most likely have a torque convertor issue or an electrical gremlin going on here? Guy that's looking at it tomorrow normally says that when one of the sensors goes bad they set off a code and my truck isn't throwing any codes.

Also, what does a stall test test if the TC isn't locked when you perform the test?

 

That why Mark K. is the man I was hopping he would chime in.

 

If the id light flashes and it stack shifts limp operation then it has a code.
There is a procedure I vaguely remember seeing another tech do to test rpm drop when engaging the converter clutch. It's been too long to remember the specifics tho.

 

Straight from a Ford Shop Manual -



Stall Speed Test

1. Connect a tachometer to the engine.

1. After testing each of the following ranges, (D), 2, 1 and R, move the transmission range selector lever to N (NEUTRAL) and run the engine for about 15 seconds to allow the torque converter (7902) to cool before testing the next range.

1. CAUTION: If the engine rpm recorded by the tachometer exceeds the maximum specified rpm, release the accelerator pedal immediately. Clutch or band slippage is indicated.
   CAUTION: Do not maintain wide-open throttle (WOT) in any gear range for more than 5 seconds.
   Press the accelerator pedal to floor (WOT) in each range. Record the rpm reached in each range. Stall speeds should be in the appropriate range.

STALL SPEED CHART <table border="1" cellspacing="0" cellpadding="3"><tbody><tr><th align="center" valign="bottom">Series</th><th align="center" valign="bottom">Engine</th><th align="center" valign="bottom">Min.</th><th align="center" valign="bottom">Max.</th></tr><tr><td align="left" valign="top">F-250, F-350, F-Super Duty</td><td align="left" valign="top">5.8L</td><td align="center" valign="top">2256</td><td align="center" valign="top">2712</td></tr><tr><td align="left" valign="top">F-250, F-350, F-Super Duty</td><td align="left" valign="top">7.3L DI Diesel</td><td align="center" valign="top">1951</td><td align="center" valign="top">2288</td></tr><tr><td align="left" valign="top">F-250, F-350, F-Super Duty</td><td align="left" valign="top">7.5L</td><td align="center" valign="top">1972</td><td align="center" valign="top">2350</td></tr></tbody></table>

If the stall speeds were too high, refer to the following Stall Speed Diagnosis Chart. If the stall speeds were too low, check engine tune-up. If the engine is OK, remove the torque converter and check the torque converter reactor one-way clutch for slippage.


__________________________________________________ ___________


Looks like a stall test can prove that a torque converter has failed. I've used this exact method myself to diagnose a failed converter.

 

It's all GREEK to me......

 

Yes and no.
The converter slip code is for the lockup clutch. That stall test checks the turbin,stator fluid coupling side of the converter. The computer looks for a difference in speed when the lockup clutch is engauged. That test is for the converter but the wrong half.

 

Without doing diagnostics on your truck I have no way of telling.

It tests everything in the torque converter EXCEPT that lockup clutch, which is the part you're having problems with.

 

Ok. Guy came. Went for a twenty or so minute ride. Thing shifted awesome. Nothing weird, etc. Get back to my house, he's looking at all sorts of things, nothing. Tell him lets go for another quick ride for kicks. Go for a two minute ride light comes back.

He says it could be a million and one things but if i want to pull the transmission he'll go through it for me free of charge and he'll warranty out the convertor in case that is the problem.

Needless to say i'm going to get food and this sucker is coming back out.

 

I'd want to see the work but I lack trust anymore.

 

Transmission is out. I'm getting way too good at this. Only took 3 1/2 hours. Rebuilt tomorrow and then hopefully going back in Wednesday/Thursday.

 

For what it's worth, I went through all of this with the exact symptoms a few weeks ago. Same code showed its ugly head as well. Turned out to be a severely failed TC.

 

at least the guy is good enough to check it out for you. Hopefully he finds something and it sets you at ease before your big trip

 

Was the question about over cooling killing the auto ever answered?

 

The only bad thing about overclocking the trans is that moisture can collect in the trans. Higher temps will drive it off. Could you get enough moisture to kill it? I suppose it's possible.