Grumpy 4l80e, Clinebarger I could use you on this one :)

[BR3W CITY]

My 4l80e is being grumpy. Its got about 5k miles on it, and I had it done locally at a shop with a pretty good rep.

1. have some shift point issue, but im 99.5% sure this is because I switched rear tire size and didn't adjust the tune



**main issue**
2. At first my trans felt like it wasn't locking up on the freeway, but I'm starting to think its actually not getting 4th at all. 3:73 at the tach says 2750 or so at around 65-70 (this is skewed due to the tire size thing as well).

My tcc brake switch looks fine, all wires are hooked up and looked to be hooked up right. I put in a new shifter because the selection-points were vague compared to the new one. Still seems to have issue, though randomly it will seem to work better.

I'm going to change the fluid, since it hasn't been done yet ,though I doubt that will change anything. My tuner is looking at it next week sometime if he doesn't get slammed and push it off again, and he is going to check the lockup/shiftpoints/ load etc etc etc.

Part of me is afraid its mechanical, with it being a new tranny and all, but that said I wouldn't think I'd have a mechanical issue this soon. I also added a larger trans cooler with a fan, and its never been raced or launched really.


I looked at the VSS' as well, wires look fine, harness is virtually brand new. What should/can I look for? My cel never came on, but i don't have a TECH scanner for trans codes.

[jfortvalley]

i would probably do the programing first and see where you are at. if the trans isnt setting any codes(need to scan it cel light or not ) i would ride around with a scanner on it and see what the computer is commanding the trans to do. if it is commanding 4th or lockup and the trans isnt doing it it will set a code .

[clinebarger]

I agree...Get it scanned. Wrong Ratio codes Means you may have a mechanical problem. Several other codes can cause this also. If it is a tuning issue....Should be able to overcome it with speed, Try 80 or 90 if it takes OD.... its in the tuning. But of coarse the other shifts would be affected.

Are you SURE its taking off in first? A stuck 1-2 shift solenoid will give you 2-3 ONLY...More like 2-2-3-3

Make double sure the trans is in D4, Shifter problems are common on swaps, Transmissions have even been burnt up because of being between detents.

Faulty trans temp sensor can cause no OD.

On a "Fresh rebuild" that's being commanded to shift but doesnt & all other test say it should.....Have a trans shop check the Fourth Clutch Housing retaining bolt (under the valve body), Very common for them to be left loose. The manual states to replace this bolt along with the Center Support bolt.

You dont need a Tech II, Though they are nice to have. The Snap-on MT2500 will do ALOT on pre CAN vehicles, And they are cheap, Easy to use, Very durable. All you need is the Body, Data cord, OBD II adapter, K-9 key & a Primary cartridge for your year or newer...The 04/05 programable are the best. I use my MT2500 alot more than my Tech II.

Of coarse EFI Live or HP tuners will give you Codes, Data & Tuning.

[BR3W CITY]

Okay cool, I'll have the tuner go for a ride with me with his laptop on his lap and see what its saying.

I agree with you on the "between detents" thing, my old shifter was for a 700r4, and it does work on a 4l80e, but the feel is a bit more vague and I had to sort of feel it out to make sure its in gear. The new one is a gated-type, elimating the guessing at least.

I'll get under it tomorrow and take the cable off, make sure by hand that its going into all 4, and that the cable is set to D4 being D4 etc, since there is some adjustability.

One more weird thing to add. Sometimes if I'm cruising at 65 with the rpms a little high, and I give it a bit of gas as we ascend a hill, THEN it decides to shift/lockup. WTF? That seems like a load related issue, which I imagine is in the tune.

Cline, what do you think the chances are of damage as a side effect (not the cause?) IT only have 5k or so miles on it, although there have been some longer trips within that.

[clinebarger]

Originally Posted by BR3W CITY

Okay cool, I'll have the tuner go for a ride with me with his laptop on his lap and see what its saying.

I agree with you on the "between detents" thing, my old shifter was for a 700r4, and it does work on a 4l80e, but the feel is a bit more vague and I had to sort of feel it out to make sure its in gear. The new one is a gated-type, elimating the guessing at least.

I'll get under it tomorrow and take the cable off, make sure by hand that its going into all 4, and that the cable is set to D4 being D4 etc, since there is some adjustability.

One more weird thing to add. Sometimes if I'm cruising at 65 with the rpms a little high, and I give it a bit of gas as we ascend a hill, THEN it decides to shift/lockup. WTF? That seems like a load related issue, which I imagine is in the tune.

Cline, what do you think the chances are of damage as a side effect (not the cause?) IT only have 5k or so miles on it, although there have been some longer trips within that.

I hope it is in the tune, Giving it throttle "up's" line pressure....If the bolt on the fourth clutch housing is loose....Boosting pressure can apply the clutches momentarily.....Lets hope this isnt the case.

If its just the tune the trans (Fourth clutches) will be fine.
If the bolt is loose....The clutches could be burnt, But they may not be. Visual inspection of the clutches is the only way to know for sure.

[BR3W CITY]

SOLVED


Went to my tuner, Tom out at West Bed Dyno Tuning in West Bend WI. These guys are great to me, and Tom has always gone out of his way (including coming to my house at 730am to do the first startup and remove VATS etc on my swap a year ago).

He pulled my tune up in HPT and we looked around at some settings, revealing a somehwat important fact for anyone using a BIG CAM. The stock computer has a setting which reads the differences in cam and crank sensors along with misfires. If misfire count is too high or the cam and crank sensor values are too far apart, the computer will disable lockup and delay shifting and kick down, similar to how improper torque management settings might act. For comfort, it removes lockup so you don't feel the "shudder" of the misfire through the driveline.
On a swapped or hot rodded car, there are enough vibrations anyway, and performance is more important than comfort. We changed the values on the misfire counter, firmed up the shifts about 20% and fine tuned the lockup and load settings.

WOWOWOWOWOW My truck runs like it NEVER has before. I can now cruise at 75mph at 2550rpm, all day long. My fuel mileage has gone up, the car is easier to drive and lockup (while still allowing my to roll just slightly to catch traffic), and is smoother and quieter since it doesnt' scream along anymore. As a bonus, engine temps have been a little lower since the engine doesn't spend nearly as much time in the higher rpms.

*Bonus, on the way home while testing the new tune out....I absolutely walked a trailblazer SS. Happy times.

[Clyde65]

Congrats! I know that sure feels good huh? makes all the troubles you have had kinda seem smaller!

[clinebarger]

Great news!!!! You didnt want ATF dripping in your face

[BR3W CITY]

hahah no i don't.
As luck would have it, my guy Tom also has ventured into building and re building auto's...or as he likes to call them his "AutoMagic". He was able to tell it wasn't mechanical pretty quick, and if it ever gets mechanical, I can always have him do a teardown for me in house.