PPE Stage 5 LB7 Allison 4-5 Shift delay??????

[number_one_scott]

Hello, I have a 2003 LB7 with a PPE Stage 5 rebuild with a 1057 converter. Rebuilt trans done way back in August - wasn't having problems until about a month ago. Under light acceleration, I know the trans will shift from 4th into 5th at around 68-70 km/h. NOW , With light throttle pressure the trans will hang 4th until I either step on it to say 1/4 - 1/2 throttle then it will shift into 5th OR if I continue to lightly throttle through, it hangs 4th then shift into 4 with the converter locked and around 90-100km/h then into 5th with converter lock. Truck is not in tow haul mode!

Before, normal operation was light throttle 4-5 at 68-70 km/h then at 90km/h 5th with converter lock would come on.....something is going on....

I've checked fluid level it is fine, I'm assuming this is a software / programming problem more than anything????

 

[mike diesel]

How could it be a software/programming problem if it was fine before?

Have you check your batteries lately? Low battery voltage can cause issues.

 

[Chevy1925]

what did the builder have to say?

 

[number_one_scott]

Mike, good point about software. Batteries are 6 months old. Been daily driving truck so no low voltage. Havent contacted builder yet, trying to see if I can self diag the problem first.

What do you think about getting a dealer to scan the truck? I have intermittently had a transmission communication error code but hasn't come on lately in relation to this problem.

 

[number_one_scott]

Would lift pump cause problems? Excessive fuel pressure at light load? Currently running 10PSI This is the most recent part ive installed on the truck within the past couple months.

 

[mike diesel]

Would lift pump cause problems? Excessive fuel pressure at light load? Currently running 10PSI This is the most recent part ive installed on the truck within the past couple months.

10 psi from the lift pump wouldn't have any I'll effect.

 

[number_one_scott]

Okay, I will start with a trans service, I only replaced the spin on filter about a month after having the trans built. Will do the inner filter as well.

 

[Chevy1925]

Okay, I will start with a trans service, I only replaced the spin on filter about a month after having the trans built. Will do the inner filter as well.

inspect the pan for material in it and the filter to see if its plugging up

 

[number_one_scott]

** Update, did a trans service last night, both filters were clean same with trans fluid. Almost nothing on the pan and spin on filter magnet. Replaced fluid with TES 295 BP fluid. No problems. BUT I will have to keep you guys posted I cleaned my MAF sensor as it was filthy wonder if this was causing problems as it shift from 4-5 fine now.