I got a new issue, the truck will shift from od-3-od all in about a second. The higher the tune, the more likely it is to do it. It only happens at light throttle, 40-50 mph and under load such as up hill or towing. I believe it's down shifting, not unlocking the converter, the rpm jump is the same as canceling OD. No changes made before this started.

Short, bad quality vid of the issue.
ODHUNT - YouTube

That is 42-ish mph, up hill, steady throttle and unloaded.

Trans temps are normal and no signs of slipping. I'm thinking this is not really a transmission issue, but a symptom of some other issue. That may be wishful thinking.

Any ideas?

 

Shift points are controlled by your tuner. Contact PHP and give them as many details as possible. Meanwhile, take it out of OD when it starts doing that.

 

This does not look to be related to the tuner. Shift parameters are different in all my tunes and it happens at same point, just above lock-up at light throttle. Shift points are controlled by many sensors using parameters set by the tunes. I believe it is seeing something thing telling it to downshift that only last second under certain conditions. The "stock" I'm referring to is still a tune on my chip and it may happen on this tune, I'm just not in this tune often and the loads are much less in the stock tune.

 

Bump, since the holiday weekend is over.

 

Do you have AE or some other useful scan tool? If so, it would be interesting to monitor Shift Solenoid 1 and Shift Solenoid 2 to see what is happening. From memory...
SS1=1 with SS2=0 is first gear
SS1=1 with SS2=1 is second gear
SS1=0 with SS2=1 is third gear
SS1=0 with SS2=0 is OD (fourth gear)

Might as well look at Torque Converter Clutch Modulated as well as Exhaust Back Pressure. If possible, record the data while you are duplicating the symptoms and post back the results.

 

Have you taken the tuner out to rule that out?

 

No AE. But this has got me thinking about getting it. All I have is a scan gauge and superchips tuner to read codes and watch things.

No, I can't get into the right speed/rpm/torque range with out tunes. My 25hp heavy tow tune is still in third at this speed and stock hasn't done it empty. Not sure if the stock tune stopped it when loaded with around 17k gross. These tunes have been fine for over 10k, I've only had the problem for the last 4-5 hundred miles.

 

Ah... we might be on to something here. Shake-N-Bake posted a topic [LINK] where he cleaned the EBP sensor. The EBP sensor sends a signal that tells the PCM what the engine load is - which has an impact on the shifts. Conducting this maintenance procedure would not be a waste of time, and it might even resolve your problem.

 

The tube was put on last spring,so it should be good. The sensor was just cleaned at that time so it is suspect. I can watch EBP and MAP to see they are line with each other. And watch the EBP numbers for any changes that don't make sense.