WOT No Shift 4l80

[GHuggins]

OK, I haven't run across this before on a 4 speed, especially a new 4l80. What's going on is it shifts normally with light to even 70 or 80 percent throttle, but try to go WOT, it just bounces off of the rev limiter until you let off slightly then it'll upshift. Data in the log doesn't even show the upshift being commanded even though it's way past the speed and rev limit setting for the upshift.

Background on the truck - it's an 01 silverado 5.3 with a retro magnuson eaton blower setup like what you typically would find on an older ford. The original 4l60 burnt up and the truck sat for yrs. Was sold to the new owner, new owner had a 4l80 installed along with upgraded injectors and pump.

I've shifted everything around trying to get it to shift - it just won't at least with wot. I'm to the point of wondering if the turbine shaft speed sensor was wired correctly, but usually when that's not there, the 80's won't shift at all. It does act like it's not seeing the rpm input though. If the sensor wiring is backwards, will it cause this? In other words if it's pinned backwards?

I even tried doing the OS swap full write again just in case something didn't take the first time, but no go. The speedo is off, but if anything should make it shift sooner not later - it's reading 10 mph higher than actual. I know there's a few things wrong in the tune in general, but they just wanted me to rough in fueling then get the trans working. I've even tried lowering shift speeds for all to the point that it's screwed up all regular shifting.

The OS came from a 2500 4wd - never had one cause a problem like this before, but who knows. Just couldn't find one from a 2wd to try.

[blindsquirrel]

Haven't I heard of that when TPS goes over 100%? (but the PID only displays up to 100, so if it's going beyond you wouldn't know) Checking TPS voltage would at least rule that out.

I found a 2WD Express van file w/80E & the same OS, it's a L31 though so don't know if it would be better or worse.

[GHuggins]

Well, I was actually going through some of the original tune that the truck already had in it and noticed several places where it's supposed to use etc for things such as a rev limiter even though it's got a mechanical throttle. I do know that mechanical throttles have adjustable tps's, so the tps part is possible. I was not aware of the tps voltage or tps reading over 100% thing. Just goes to show we always learn new things. I know this engine isn't the soundest. Has something pretty bad out of balance whether it be the converter, blower or engine itself. Also is performing baro updates with the boost and throwing fueling off.

[blindsquirrel]

Just speculating, but would anything horrible happen if you modified the throttle stop to limit it to ~95%? As far as I know that would also prevent it from doing the WOT baro update. I don't know what the threshold for that is though.

[GHuggins]

As long as it fixes the wot shift issue, it shouldn't hurt a thing. I also don't know the exact specifics for the baro update, but I imagine that would probably still take place at 95 or even 90 percent.

I hadn't really thought about adjusting the stop - This is why it pays to get second opinions
Thank You

[blindsquirrel]

BTW, I found your unicorn file -
2002 Silverado LQ4 4L80E 1GCGC13U22F236000 (OS 12212156).hpt

[xx_ed_xx]

Since I am having a similar issue with swapping the whole drivetrain into a lighter vehicle and the pcm engine and trans and wiring are all the same. I was going to play with WOT mph and rpm first mine is DBW so cant really stop it lol

[GHuggins]

Well I tried it. Didn't work - had my fingers crossed though, so did some more digging into the pid list. Finally found the ISS / turbine speed sensor readings - nothing. Tried various different OS's since I did notice on one that even though I had done the swap the ID's weren't matching up when compared a second time. Still no go. They swear it's in the right pins at the ecm even though I didn't look into it myself. They did a quick swap at the trans of the speed sensors just to see if it was a bad sensor - didn't work, so either pins at the ecm or ecm itself not fully taking the OS swap at this point. They're supposed to double check the pins at the ecm tomorrow.

[blindsquirrel]

Your P0716/717 are No Error, the real 80E/2WD file has those as No MIL. Bunch of other trans DTCs different too.

[GHuggins]

Aren't I the one usually pointing these things out

Yeah, not even running a tune with a trans cal close to that one right now - put it back like it was before I started skewing everything for testing. I should have known to look at the sensor reading sooner. Just didn't think anything about it since the regular changes for speed settings for the normal tables were working. I'll have to check the current tune to see what dtc's are set to in it. Honestly the dtc settings in that one should have been OE unless they didn't get swapped over like they typically don't.

[RDF1]

Can you set WOT RPM to 4000 and the PT From 75%+ and WOT to the equivalent of what 4000Rpms would be in that gear?
Every now and again i have to fudge the numbers with a 4l80 swap to get the WOT shifts correct. Also correct the Speedo and the PCM speed.
Gen 3 has some behind the scenes stuff going on with the shifting and calculated speed vs what is actual shown on dash and Scanner.

[GHuggins]

Just posting a follow up. The pins for the turbine speed sensor were apparently in the wrong ecm connector. They got them swapped around and even though I only had about 30 minutes to knock it out as I was passing through, I got it pretty well dialed in. I know all of the dtc's aren't necessarily setup correctly, but honestly forgot to check them. Was aggravated enough with having to go back again to finish it up plus they had 2 other cars there they wanted me to look at real quick so I sorta forgot about the dtcs. Then on top of everything she was finally running good enough to stress a few things - exploded the tensioner and shredded most of the belt off for the blower, so yeah......

Since it is a 4speed and nothing really special anymore, here it is for anyone wanting a decent shifting setup. Tow haul is setup to unlock the converter and shift to 2nd gear when you hit the button for racing setups...

[kingtal0n]

How do you get into 'tow haul' mode? I have a performance mode button momentary ground activate but I didn't know there was a different pin for tow haul?

[GHuggins]

Performance and tow haul are the same in the calibrations, so essentially when your grounding the performance pin it's the same as pressing the tow haul button.

[kingtal0n]

but aren't there two completely different maps for those ? hmm

[Shrek]

but aren't there two completely different maps for those ? hmm

No.

The terms "Performance" and "Tow / Haul" are often used interchangeably to describe the same Part Throttle Shift Speed Table, and the same Shift Pressure Table.

With a Gen 3 PCM (P01 or P59) there are four Part Throttle Shift Speed Tables:
- Normal
- Performance (also referred to as Tow / Haul)
- Cruise
- Hot

[kingtal0n]

Ah thanks. Its been months since Ive looked at my file. I just remember there were a bunch of extra tables I never filled out and remember seeing tow or something
Guessing cruise is for cruise control? eh

[TheMechanic]

Not saying this is the problem but something you should check.
https://forum.hptuners.com/showthrea...ht=rev+limiter

[Shrek]

... Guessing cruise is for cruise control? ...

Yes - the Cruise shift tables will be used whenever an OEM style Cruise Control system has been activated to maintain a set vehicle speed.