TC Clutch Slipping - Type F or Lucas Trans Fix?

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So the ZF 5HP19FLA in my Audi is having a problem keeping the torque converter in lockup at highway speeds when it encounters any kind of hill. It will accelerate normally for a few seconds, but will pop out of lockup when going up any hill and trying to maintain speed. The disengage is noticeable, unlike if it was operating correctly and it would be imperceptible. It will repeatedly do this for my 25 mile commute at every incline, and eventually it will set a hard CEL of P0741 which is TCC performance/stuck off. Then it will not attempt to go into lockup at all unless I rest the code. Rinse and repeat.

I've replace the torque converter because these ZFs are known for the internal seal being of poor quality and causing this problem. Nothing changed, so I then looked at the valve body being the issue. No go there, either.

Now I'm thinking that I'd like to drive it for another year and then part ways with it. Would increasing the operating viscosity significantly possibly improve its ability to hold the TC in lockup? Would adding some Type F in the mix help it to hold better? At this point, I'm shooting in the dark, and if either one would make no difference then I guess I'll just drive it as is and start looking for my next vehicle. Thanks.
 
I've been diligent in changing out the ATF on a regular basis.

I have no idea if there is a separate solenoid to activate the TC clutch, unless it is inside the valve body. I know there are 6 solenoids at the back of the VB that activate the various clutches and one of them is for the TC clutch. Across 3 VBs, the symptoms stay the same, so I deducted that the solenoid is functioning.
 
Quote:
so I deducted that the solenoid is functioning.


How many miles on the tranny?

Not necessarily.

The solenoid is an electro-mechanical device controlling a valve.

The solenoid could be intermittent, or the valve it controls could be varnished, or the valve is leaking.

Let's assume for the moment it is varnished before going further.

Try adding a bottle of LubeGard Red and let's see if that fixes it.

Do not use any other type of fluid or for certain don't use the Lucas goo.

It could also be that the actuator that locks up the TCC has problems,
 
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I had an old Ford pickup as a daily driver that the torque converter lockup had been unplugged before I bought it. I never even so much as plugged it in to try it in the seven years I had the truck and it still got 16 mpg. That was before check engine lights were a thing, though.
 
Originally Posted By: MolaKule
Quote:
so I deducted that the solenoid is functioning.


How many miles on the tranny?

Not necessarily.

The solenoid is an electro-mechanical device controlling a valve.

The solenoid could be intermittent, or the valve it controls could be varnished, or the valve is leaking.

Let's assume for the moment it is varnished before going further.

Try adding a bottle of LubeGard Red and let's see if that fixes it.

Do not use any other type of fluid or for certain don't use the Lucas goo.

It could also be that the actuator that locks up the TCC has problems,


I'm about to roll over to 200k on the trans. I've had various amounts of Lubegard Red in there since 100k miles, but at this point with the three recent pan drops and refills there probably isn't much left in there.

I was only looking at the Lucas as a tool to increase the viscosity. When driving it, it almost feels like an internal seal somewhere in the TCC lockup system won't hold pressure with the 8.0cSt fluid in there now and maybe it would do better with something closer to 10.0cSt viscosity. The other more expensive option is and entire fill of Redline Racing ATF.
 
You have a lot of miles. I was dealing with slipping during upshifts for 3-4 years now, only when the tranny was cold. I know you have a different issue. I have tried Lucas which was like molasses and made issues worse. Lubeguard Red helped but didn't solve it and the upshifts starting getting worse again. I recently tried sea foam and the upshifts are perfect now under all conditions. Perhaps the valve body/ seals are gummed up.Just a suggestion.
 
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Fluid maintenance has been D&Fs every 30k miles from when I purchased at 60k.

I've spent much time on those sites looking at new and upgraded parts. At this point, the car is just not worth $1000 of upgrades. Even deciding to spend $600 to have the converter replaced was not an easy decision, but since it was a well known problem I thought it would certainly fix the issue.
 
I would think you would feel it slipping rather than just popping out. Lucas is a last resort but your thinking IMO is sound. I suspect my trans has a weak pump, and lucas makes a difference between it driving almost like new vs horrific downshifts so bad the gauges quit, the lights blink, and one worries about engine mounts. no kidding. Lucas for 2 years and we'll still take the van out of state. It's a poor fix, but has worked for now. I agree with the above that it does sound like hard part wear. Perhaps pressures are not strong enough for partial engagement?
 
Originally Posted By: threeputtpar
Originally Posted By: MolaKule
Quote:
so I deducted that the solenoid is functioning.


How many miles on the tranny?

Not necessarily.

The solenoid is an electro-mechanical device controlling a valve.

The solenoid could be intermittent, or the valve it controls could be varnished, or the valve is leaking.

Let's assume for the moment it is varnished before going further.

Try adding a bottle of LubeGard Red and let's see if that fixes it.

Do not use any other type of fluid or for certain don't use the Lucas goo.

It could also be that the actuator that locks up the TCC has problems,


I'm about to roll over to 200k on the trans. I've had various amounts of Lubegard Red in there since 100k miles, but at this point with the three recent pan drops and refills there probably isn't much left in there.

I was only looking at the Lucas as a tool to increase the viscosity. When driving it, it almost feels like an internal seal somewhere in the TCC lockup system won't hold pressure with the 8.0cSt fluid in there now and maybe it would do better with something closer to 10.0cSt viscosity. The other more expensive option is and entire fill of Redline Racing ATF.


When you did your pan drops..did you replace the transmission filter? I ask because Audis of your model's pedigree had the problem of being sold with the promise of "lifetime" ATF..and as a result the ATF and filters were never changed till later in the car's life, if at all.

I've changed a few Audi transmission filters..late 90's models with 100K miles or so and never been serviced. The filters elements were visibly blacken..the ATF looked fine..a change of filter and a few ATF re-fresh changes and the transmissions seem to hold up fine.
 
it sounds as if your converter has failed again, I just did this in my B5 S4, you could feel the converter lock up and the revs would climb as if it was half locked up. I purchased an advance automotion converter and installed it myself, any idea what brand you had installed? Some reman converters are garbage, I specifically bought mine because of the 3 year warranty.
 
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