Strange 2-3 Shifting

[pmcgrath]

I decided to do some logging the other day as I wanted to see what the car would shift at on its own on the 2-3 shift. I was also trying to see what kind of drop in rpm I was getting on the converter lockup. Anyway, when I was close to the top of 2nd, it shifted to 3rd for a second, then went back to 2nd and then finally shifted to 3rd again for the last time. You can see the strange behavior in the log. I have included screen shots in the attached document. It all happens in a matter of a second or two. It isn't slipping into gear at all either. They are positive shifts. I haven't tried shifting manually yet.
The tranny has a ck servo and one of his older recalibration kits. Also, I recently installed a new pump assembly from Dave Husek in the hopes of curing a wot lockup issue, which it did.

Thanks

 

[TurboDave]

Post the the graph page instead of the data page. Less busy and easier to see on the graph.

 

[TurboBob]

the ECM is reading a switch in the transmission that is detecting fluid pressure. Could be a drop in pressure, a bad switch, bad wiring , or a bad ECM.

Bob

 

[pmcgrath]

I wanted to give the detailed screen because you can see the 3rd gear indicator on it. Just look at speed, rpm and the 3rd gear indicator in the screen shots.

Thanks

 

[pmcgrath]

Ok, well here's the entire log. You can start looking around frame 484.

Suggestions?

Thanks

 

[TurboDave]

Ok, well here's the entire log. You can start looking around frame 484.

Suggestions?

Thanks

Thanks. Seeing the entire run on the graph screen is very telling. Set one of your graphs to RPM and you see pretty plainly what is happening. For example, your "actual" 2/3 shift occured at frame 503 (notice the steep rpm drop from 5700 to 5000. Typical of a good shift point.

Now go back to frame 444 and you can see where the car had enough tps and load to cause the 3/2 down shift as you were approaching WOT.

The first indication of trouble is at frame 486 when the 3rd gear flag comes on again(but you can see there's no indication of an actual shift)
Goes off again at 493, on again at 501, off at 502, and finally on again at 503 where you can actually see the real shift occuring.


BTW, at frame 546 you can see the TCC lock, and the resultant drop in rpm for that. It's a long slow rpm drop indicating your TC clutch is on it's way out.

Looking at the graphs, I agree with Bob, you've got something flaky going on with the 3rd gear switch or internal pressure, or flaky wiring connections.

 

[pmcgrath]

Thanks for your input Dave.

What's strange is the car didn't do this when I was using the stock servo and my previous tc ... even with a pump producing lower pressures. Maybe I'll put the original servo back in there just to see if it behaves the same.

By the way, how quiclkly do you see rpm drop in Powerlogger after the converter is locked at wot? Mine took about 14 frames to see the max rpm drop after locking.

Thanks again

 

[TurboDave]

Mine might not be such a fair comparison, I use a multi disc vigillante converer. It completes it's rpm drop in just over 3 frames (faster actually than a gear change).

The amount of time it takes yours to pull the rpm down reminds me of what my stock converter looked like when I was locking it at WOT. Single disc converters cannot handle WOT lockups for very long at all.

 

[pmcgrath]

That is locking pretty quickly, especially given that Powerlogger records at 20 frames a second..

Thanks

 

[c&cgn]

Mine might not be such a fair comparison, I use a multi disc vigillante converer. It completes it's rpm drop in just over 3 frames (faster actually than a gear change).

The amount of time it takes yours to pull the rpm down reminds me of what my stock converter looked like when I was locking it at WOT. Single disc converters cannot handle WOT lockups for very long at all.

I will respectfully disagree on the single disc statement. Yes, a Vig or others never seem to be able to survive at high HP very long, but the TC Paul has came from me after being freshened by the company that built it.

It has been 133 mph in my car with no issues. I have several other buddies who have run 125mph - 135 range consistently with the same type of converter for many, many years.

This converter is a local secret of sorts.....and I have not posted my disagreement over the years with the statement that "single disc converters won't last" because I did not want to subject myself to the internet arguments that would certainly take place.

This converter (and many others built by the same company) have been proven locally here for years. Too many guys have used it for it just to be a "fluke".

 

[TurboDave]

Well then, we agree to disagree. Looking at the rpm trace on the PL confirms that fact that the clutch is being eaten alive. That's the same kind of long (14 frames) rpm drop displayed by the stock converters I was burning up in the mid 90's. A good (even single disc) converter will take FAR fewer frames to drop the rpm during a WOT lockup. Single disc converters simply are not made to withstand WOT lockups.

 

[c&cgn]

Well then, we agree to disagree.

Fair enough, we'll just leave it at that. I think that several hundred passes in the 10's between myself and several other guys that run this converter pretty much speak for themselves.