4l80e lockup slippage what is normal

[racin69z]

I am tuning a 2002 2500 hd 6.0 4l80e using HP tuners. Original motor trans and PCM to the truck. 260K miles. I rebuilt the motor and trans this spring and I'm trying to dial it in. I am having some converter slippage/trans overheating problems that I am trying to diagnose.

Before tearing the truck down, I had no driveablity issues. The rebuild was just a precautionary measure trying to avoid the inevitable considering the mileage. I do a long trip about every summer towing a 8k trailer cross country. I did some mods/upgrades to the motor and trans that imagine will require some fine tuning.

List of mods just in case it is pertinent to the problem:

Motor: .5 more compression (10:1) running 862 5.3 heads (mild bowl porting and chamber unshrouding) 2.00 intakes stock exhaust valves 208-216 113 lsa .500 .500 lift cam, NNBS intake 5.3 FF inectors, Volant cold air intake.

Trans: Found the AFL limit valve to be worn in the valve body (used the transgo kit to restore the bore and valve), Forward drum was worn where the sealing rings ride (used Sonnax oversized sealing rings to repair) Sonnax line pressure booster kit, Sonnax TCC regulator valve with the firmer apply spring installed, Sonnax 2-3 and 1-2 shift valve springs, rollerized rear, dual fed direct drum, a few planetary lube holes drilled slightly oversized where recommended, .040 Line to lube hole drilled in the pump, all new AC delco solenoids and pressure transducer, all new alto high energy green clutches, steels, bands, bushings and thrust washers. End play set on the tight side of spec. Florida torque converter upgraded towing converter (supposed to have the failure prone lockup piston tig welded and an upgraded friction material).

Sorry for the info overload, I just dont know exactly how the mods affect the required tune. I am not sure if my problems are tune related or are mechanical/electrical problems with my trans.

Everything seems to be running fine, and I'm working on learning to tune. The trans has had 2 issues:

At very low load flat ground at about 45-50 it bounces in and out of lockup. I've played with some settings trying to keep it locked, but no changes. Doesn't happen very often.

I took my first long trip on the interstate the other day running 75-80 mph. I live in the hills, so it takes a fair amount of throttle to maintain speed on the hills. After about 40 miles the trans started getting hot. At low load flat ground the TCC slippage shows virtually no slippage rpm(0-5 rpm tops). As I approach a hill and begin to add throttle to maintain speed, the slip rpm climbs all the way up to around 350 rpm. The TCC PWM duty cycle shows 99.2% when this is happening.

The VCM scanner doesn't have much in the default channel setup for trans stuff. I added the TCC PWM, engage mode, and slip rpm. I assume folks will want a log file to help troubleshoot. Is there any other things that I need to add to the log to get good data?

Any help would be appreciated.

Lynn

[hatzie]

It sounds like you have leaks in the TCC apply circuit or you got a bum converter.

You've probably already done this but... I'd verify the basics are OK by running through the TCC troubleshooting tree in the GM or ASTG service manual...

[racin69z]

So I went through all the troubleshooting info I could find on the internet and in my ASTG manual. I am still having trouble.

I found a table in HP tuners that allows me to modify pressure in the TCC circuit. I have it where it will drive great by itself, but it is very inconsistent towing.

Sometimes it will lock up solid and sometimes it will slip. I am at a loss as to what I need to repair or replace.

Any ideas

Lynn

[AussieinNC]

It is possible the "slippage" when towing even after pressure upgrade may be the convertor lockup clutch is toast....

There are also several TCC valve system upgrades available to enhance the lockup pressures....

[WorkinLonghorn]

I had a new lock-up convertor slip and it produced a burnt smell in the fluid within about 1000 miles if memory serves.

[racin69z]

I made my best effort to upgrade the lockup system when I built the trans. I went with the Sonnax line pressure booster kit, and teflon sealed lockup valve with the firmer apply spring. And the converter I bought was supposed to have an reinforced apply piston and upgraded friction material. Well, so much for that Lol.

As for an update, I added another external cooler. So now it foes through the radiator, through an 11x11x.75 stacked plate cooler, then through a 11x11x1.5 stacked plate cooler. We are 700 miles in to our trip home and it has not been above 200* I still have had more slip than I want a couple times. I made a tune change and added even more pressure to the TCC circuit and it seems to have helped. It is very intermittent. The fact that it sometimes locks up solid as can be steers me away from the converter piston and lining.

[AussieinNC]

Whenever I add an external cooler I always totally bypass the radiator porting....I add plugs to the radiator ports to prevent any water loss if the radiator cooler ever dies....

Most engine water temps nowadays are over 210....which can reduce the efficiency of the plate air based coolers....the trans fluid could be matching the water temp then cooling down a bit when run thru the plate coolers....

Make sure the coolers have sufficient air flow thru them....and are not stacked one behind the other....