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OK tranny guys 4L80E Q's

GJF

GJF

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On the 4L80E, what controls the shifting speed? My tranny shifts but when I shift into reverse there is a few second delay til it engages. It engages and there is no slip just a delay. Also it seems it take a little time shifting from first to second. It doesn't run hot the fluid looks good. I tow my trailer all the time with no problems it just takes a little longer during 1-2 and reverse. Is there a known fix?
 
Its all controlled electronically. There are provisions for shift delays, but I havent seen them actually used in the programming.

The 1-2 could be how Heath programmed the shift point, which is by speed and throttle position, which the fuel curve comes into play as well, because if you change how much fuel you have at a given throttle position it ripples into the tranny tables on when you should be shifting and how much pressure is needed now at a higher or lower throttle position.

It could also be that you need to adjust your VSSB for slightly taller tires. What were the stock tires? Yours now are about 32" and if the stock ones were only 30" tall than it would be good to adjust your VSSB for the speedo and PCM speed input.
 
B&M sells a little tap in control box that helps the 4L80E (along with others) shift better. It has a 3 position switch. I have had two of these and personally have that they were great. I dont know if it will "goofy" things with Bill's chip but they are not that expensive. Just my .02

It is called B&M shift improver plus. IIRC
 
This truck has done this since I bought it 1 1/2 years ago. Even with the original ECU and stock tires. It only shifts sooner since the Heath reprogram. It has a pronounced delay when it reverse and takes a bit of time between 1-2 shift. I was wondering if the valvebody has some leaking seal or possible a sensor that is out of range or faulty??
 
A scan tool and transmission pressure gauge will tell you what is happening.When the tranny is shifted into any gear from park or nutural the pressure should jump up. With a scan tool you can manually raise the pressure by setting the force motor to a higher setting. It goes back to the programed setting when you disconnect the scan tool. It's just for testing purposes. The pressure valve can wear as does the tcc valve does. A company called Sonax Makes a kit to bore the valve out and install a sleeve for both the tcc and pressure valve. It's called The Sonax Shure Cure. This place and many others sell the kits http://www.bulkpart.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=2&Category_Code=4L80E Fairly easy to install from what I'm told.Never done one myself.
 
I also got a kit that included the 1-2, 2-3 shift solenoids, the pressure manifold switch, TTC solenoid, internal harness, EPC solenoid and the speed sensor. All easy to do with the pan off. Put a bottle of the Lubeguard in and it shifts like a dream now.
 
If the pressure overall is low then is there one valve that regulates line pressure? If the line pressure is too low would it make everything shift sluggish?
 
I replaced the epc selenoid and it greatly helped my slipping problem. It's also adjustable but i did nothing to mine just put it in. Didn't notice any diff on shifting
 
The 4L80E has a couple of inherent flaws in them that cause the 1-2 hang-up and slipping for no explainable reason. TRANSGO makes a kit to fix the valve body and the HD-2 shift kit will fix the 1-2 hang-up provided the trans is still good inside. To fully do the kit though, you need to drop the trans and drill out one of the passages at the pump for improved flow and torque coupling(it helps the converter grab sooner and hold stronger is how it was explained to me).
 
I called Bill at Heath this afternoon and hoped he would have some insight. No real luck he hasn't recalled symptoms as mine before. I did inquire about the shift kits, he did not care for them? He suggested to see a accedited tranny shop and have them hook up a scan tool that troubleshoots the tranny from the port under the dash.
 
As you suspected you probably have a pressure problem in the tranny. If the problem is more pronounced under load with a trailer its because you need to put your foot into the pedal more to get going. With the tranny pressure curve, more pedal equates to more pressure to prevent slipping and this delay in shift. You must not be getting that pressure. So a new pressure control solenoid would probably resolve the issue, not too expensive either. And good to replace TCC solenoid at same time and do the Sonax/Transgo modification.
 
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The actuator limit valve is a WELL known issue in the 4L80E and will cause all kinds of shifting issues. It controls the fluid pressure to the solonoids that actuate the shift valves and thus if it is low then it will not full activate the shift valves causing delayed shifts or slipping. TRANSGO and SONNAX both make it a kit to correct this, but it requires buying a reamer as the valve wears the bore and begins to side load and stick so it must be resized and an oversized valve installed. Also the 1-2 shift is well known and is refferred to as a the slide bump 1-2 shift. It is often caused by the accumulator piston sticking and then releasing which in effect causes a funky delayed shift. The accumulators job is to soften the shift by acting like a shock absorber for the fluid to compress against. If it sticks or bleeds off fluid, this will cause engagement issues as the fluid that is activating the clutch or band is the same fluid that is compressing the accumulator valve. TRANSGO's HD2 shift kit ha a correction for this to crispen up the 1-2 shift as well as to staedy out the line pressure as the 4L80E has had many failures from the line pressure spiking. This is why I will not use an inline plug in chater box but rather address the problem internally where it is at.
 
Would it just be better to replace the pump assembly? What about replacing the valve body housing as well?
 
Anyone here done the Sonnax Sure Cure themselves? The reamer kit costs $150 and I could probably pay a shop to do the install for that expense. Unless some cheaper tool will do the trick. And do you still use new solenoids, or repairing the old ones? The kit is like $85.

And are there other fixes that should be done when in there?
 
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