won't upshift 2-3 or 3-4 @WOT

[Russ in CT]

After a recent unrelated service by local mechanic, my '99 Ex, 4.0 SOHC, 5R55E will no longer upshift @ WOT from 2nd to 3rd or 3rd to 4th. It seems to shift normally just driving around, and @ WOT it shifts 1-2 properly, but the 2-3 and 3-4 shift won't occur if I have it floored unless I back off the throttle. If I don't back off it just sits there at redline screaming for mercy until fear of detonation impels me to back off. As soon as I back off a bit, it upshifts.

I know it didn't have this issue before it went into the shop, since my daily commute includes a merge onto a busy highway from a dead stop & almost no ramp (Wilber Cross Parkway in CT), so virtually everyday I'm foot to the floor up to 65. I noticed the problem the first day after getting the truck back from the shop. I would have noticed if it had this issue before then.

The work that was done was for the timing chains, jackshaft chain & tensioner, front cassette, and also the front and rear tensioners. So that means they removed the upper and lower intake, the front timing cover, water pump, left side valve cover, and all the hoses and connections required when taking that stuff off.

Is there some connector or something that they didn't reconnect that could account for this?

The truck has 180K miles, but the tranny was rebuilt, it has about 40K highway miles on the rebuild.

Any ideas? Shop says nothing they did could have caused this. They say the shifting is controlled by the computer, which uses signals from TPS and rpm's to determine shift points. So it would have to be a TPS or computer problem. But it started as soon as I got it back from them, so what gives? Ideas?

 

[2000XPLORERSPORT]

After a recent unrelated service by local mechanic, my '99 Ex, 4.0 SOHC, 5R55E will no longer upshift @ WOT from 2nd to 3rd or 3rd to 4th. It seems to shift normally just driving around, and @ WOT it shifts 1-2 properly, but the 2-3 and 3-4 shift won't occur if I have it floored unless I back off the throttle. If I don't back off it just sits there at redline screaming for mercy until fear of detonation impels me to back off. As soon as I back off a bit, it upshifts.

I know it didn't have this issue before it went into the shop, since my daily commute includes a merge onto a busy highway from a dead stop & almost no ramp (Wilber Cross Parkway in CT), so virtually everyday I'm foot to the floor up to 65. I noticed the problem the first day after getting the truck back from the shop. I would have noticed if it had this issue before then.

The work that was done was for the timing chains, jackshaft chain & tensioner, front cassette, and also the front and rear tensioners. So that means they removed the upper and lower intake, the front timing cover, water pump, left side valve cover, and all the hoses and connections required when taking that stuff off.

Is there some connector or something that they didn't reconnect that could account for this?

The truck has 180K miles, but the tranny was rebuilt, it has about 40K highway miles on the rebuild.

Any ideas? Shop says nothing they did could have caused this. They say the shifting is controlled by the computer, which uses signals from TPS and rpm's to determine shift points. So it would have to be a TPS or computer problem. But it started as soon as I got it back from them, so what gives? Ideas?

i can kinda relate to this.i got my trans fully rebuilt a year and a half ago.but for a while i noticed at wot going from i believe 3-4 it revs up high then shifts.even if i dont back off.now at normal driving it shifts fine every gear.it doesn't do this everytime.but sometimes it does.when i floor it and it shifts from 2-3 you can feel and hear it rev up like it doen't want to go,but after a few seconds it goes into gear.sometimes i can tell even before it gets to that shift point if its going to hang up like that.sometimes at wot i can tell the truck is not going as quik as other times,and then when it come to shift at that moment,it revs up to like 5000 rpm,then goes into gear.

 

[Russ in CT]

Anyone? What controls the 2-3 & 3-4 upshifts? Do they share a valve in the valvebody, a common solonoid, a common electrical connector to the solonoid(s)?

 

[hunterdan]

How about the throttle position sensor? Might not be reading properly at WOT.

 

[35Remmy]

Are you guys sure you're not talking about the 2-3 or 3-4 FLARE that is SOOO common in the 5R55E transmissions? It certainly sounds like it.

You're basically saying that it revs up before it "slides" or falls into gear, right?

MY problem is that while i'm in OD...I want to shift out of it to gain speed, so I give it a LOT of gas...THEN it FINALLY shifts but the motor screams up to like 4,000RPM's first. This is WITHOUT letting off of the gas first. It's not flaring or slipping, just requiring a lot of throttle to get it out of OD.

 

[Russ in CT]

No, not flare, not slipping. If I plant my foot on the floor, the thing will not shift, period. It'll just stay in gear rev'ing until the engine explodes (well, I suppose it would explode, I haven't actually tested that yet).

Driving around 'normally' I didn't notice anything odd. But when I floored it trying to merge onto the highway from a dead stop (that’s how its done on the Merrit Parkway/Wilber Cross), the 2-3 and 3-4 shift simply did not occur at WOT. Only if you finally let off a little does it upshift. I tested it a couple of times on different days to make sure I wasn’t simply patient enough. That last time I really waited as long as I dare to see if it would upshift, I had to let off for fear of destroying the motor.

This is not coming from someone that just doesn’t know where redline is, or when its supposed to shift at WOT. My daily commute has me flooring the gas from a dead stop up to around 65 mph just to get onto the highway. I experience WOT redline shifts on a daily basis.

 

[CDW6212R]

Send a message to Chris(Glacier), he likely will point you in the right direction.

I just changed my EPC again, plus the Sonnax three o-ring plugs, and two shift solenoids. I haven't tested WOT going through 2/3 or 3/4 yet, but I got close with the 2/3, and mine was past 5600rpm when I let off. I have a little different shifting in my 99 truck now, mostly better.

 

[Turdle]

Moved to the proper sub forum.

I second the motion for you to check the TPS
They can be "knocked out" very easily.

should be less than 1v at rest-around 4.75v at WOT ( no higher than 5v)

 

[CDW6212R]

That's a good idea, I missed Dan's post.