4l80e questions

[denny]

Just got 4l80E and converter rebuild, here the problem

1. take approximately 6 seconds to fully engage Drive Reverse engage right away, under a second
Line pressure is about 60psi in P, N &D
130PSI in R

2. The MPH on the TCU is showing less than the actual MPH the truck is moving
Ex. I am driving 65mph, the TCU is showing 42mph
This is messing with the shift and TC lockup point

Any ideas?
My tranny guy have been sick , I haven’t been able to take the truck to him yet.

 

[Quickstop [UK]]

Re: 4l80e questions

1) Am looking at the technician manual I have for the 80e and the difference is the clutches.

In R, the rear band and the direct clutch are applied.
In OD, the Forward clutch is applied and the other two aren't. The Low Roller clutch is holding in 1

The same solenoid is used for both (solenoid A).

160psi in R and 60psi in OD sounds like you have lower line pressure due to a leak or bleeding off somewhere - accumulator taking time to fill/compress/apply everything? Did you put in a different valve separator plate? Are the check balls the right size?

Want the manual? I can PM you a link...

2) in the setup programme, has it changed the pulses per mile in order to calculate speed? Did it go back to default I mean?

 

[denny]

Re: 4l80e questions

1) Am looking at the technician manual I have for the 80e and the difference is the clutches.

In R, the rear band and the direct clutch are applied.
In OD, the Forward clutch is applied and the other two aren't. The Low Roller clutch is holding in 1

The same solenoid is used for both (solenoid A).

160psi in R and 60psi in OD sounds like you have lower line pressure due to a leak or bleeding off somewhere - accumulator taking time to fill/compress/apply everything? Did you put in a different valve separator plate? Are the check balls the right size?


Want the manual? I can PM you a link...

2) in the setup programme, has it changed the pulses per mile in order to calculate speed? Did it go back to default I mean?

CKPerformance.com built it, I am not sure of what he changed. He did change something to make it shift firmer.


I am using PCS tcu, i did not change the setup from what it was before the rebuild. I will look at the pulse per mile setup.

Thanks

 

[ajt86]

Re: 4l80e questions

to change the shift firmness without using the controller he problably stacked washers in the accumulator to increase the spring pressure. if the seal got rolled or cut reinstalling the accumulator it can give you a extended engage- but it would usualy also cause a soft shift

 

[JSM]

Re: 4l80e questions

speed it typically the wrong gear ratio setting, or tire diameter in the computer controlling the trans.

 

[denny]

Re: 4l80e questions

speed it typically the wrong gear ratio setting, or tire diameter in the computer controlling the trans.

The settings haven't changed in the tcu settings.
I checked again

tire dia - 25.6
final drive ratio - 3.420
Gear ratios
1st - 2.478
2nd - 1.478
3rd - 1.00
4th - 0.749

 

[JSM]

Re: 4l80e questions

the tcu gets the speed input from the output speed sensor directly from the transmission. Very direct link not dependent on any wiring from the stock syty system. I have not had one where tire dia and gear ratio's were set that it was not correct.

 

[denny]

Re: 4l80e questions

the tcu gets the speed input from the output speed sensor directly from the transmission. Very direct link not dependent on any wiring from the stock syty system. I have not had one where tire dia and gear ratio's were set that it was not correct.

Thanks

I think i got the TISS and TOSS plugs mixed up, just switched it, waiting for the rain to stop to test drive.

 

[denny]

Re: 4l80e questions

Both problems solved, I don't believe i made such a stupid mistake.

Thanks

 

[Captain Morgan]

Re: 4l80e questions

hey, at least it wasnt a costly stupid mistake. sometimes talking it out is all you need to do. glad its fixed.

 

[JSM]

Re: 4l80e questions

Some of the harnesses for the computers honestly suck as they don't label the tiss and toss correctly, might want to label at least one of them in case you have to remove them in future.

 

[518]

Re: 4l80e questions

Glad it was ez for you. Where in ny are you

 

[denny]

Re: 4l80e questions

I label it already.

I am in Long Island, close to Queens.

 

[Quickstop [UK]]

Re: 4l80e questions

Damn! Glad you got that figured out!

 

[Windedv6]

Re: 4l80e questions

Had the same happen to me once. A new TCI controller harness had the TOSS and the TISS labels switched. We caught it when we loaded the file and saw the mph varying with the motor rpm... while the truck was sitting still. Glad you got it fixed.

John

 

[0966Sy]

I was waiting to see what someone with experience was going to suggest. Glad you got it fixed.

Are you back on the stock ECM or still on the BS3? Had any feedback on controlling the 80e with the BS3? Dealing with two systems always seemed like it would be a pain in the butt.

 

[Windedv6]

Re: 4l80e questions

Not a big deal with a stand alone controller. Once it is setup correctly it is rarely needed to go back in. If your are doing some serious racing and want to experiment for some nanosecond gain then maybe. I set up mine originally and only when back in and change my shift point into over drive when cruising. I had it set a little to low and at 45 mph in town traffic it to shift into overdrive which wasn't needed. I bumped it to around 50 mph and it worked out great. Other than that, I didn't need to go back and play with the tune.

John