PaulW

And if we could send a different signal to it so the system pressure was higher, do you think it would do anything to the tranny operation, i.e. make it shift smoother and crisper?

KaMaKaZieP -ALUMIN8-

There is a switch that can be rigged that causes the ATF to run at full pressure and cause very solid and crisp shifts.

KaMaKaZieP -ALUMIN8-

<ul><li><a href="http://forums.maxima.org/showpost.php?p=2720334&amp;postcount=60">http://forums.maxima.org/showpost.php?p=2720334&amp;postcount=60</a</li></ul>

tozoM8

The first on the left. It is shorter than the others and works the opposite way. It works from 5.5 bar ( 82 psi) to 0.5 bar (7.5 psi).The other pressure regulator valves work from 0.4 bar (6psi ) to 5.4 bar (81 psi ). The solenoids for the clutches rated 12 V 5 bar (75psi )
Eddie told me, that this is only a control pressure for the valve body so the solenoids and pressure regulator valves only control the spring loaded valves so the clutches have higher pressure. He also said, that in reverse the pressure almost twice as much. A few months ago I've tried to overwrite the TC control valve with 12 Volts and it went into limp mode right away. We need to remember, that this is a well designed system, it works perfect when it is new, so it start to hunt because something changes. Mine tranny has only 32K miles, but all the other components have 110K. I don't think it has a software problem because non of these cars hunted when they were 2-3 years old. Mobil 1 does the trick for me, but I still don't understand why. the opposite way. It works from 5.5 bar ( 82 psi) to 0.5 bar (7.5 psi).The other pressure regulator valves work from 0.4 bar (6psi ) to 5.4 bar (81 psi ). The solenoids for the clutches rated 12 V 5 bar (75psi )
Eddie told me, that this is only a control pressure for the valve body so the solenoids and pressure regulatot valves only control the spring loaded valves so the clutches have higher pressure. He also said, that in reverse the pressure almost twice as much. A few months ago I've tryed to overwrite the TC control valve with 12 Volts and it went into limp mode right away. We need to remember, that this is a well designed system, it works perfect when it is new, so it start to hunt because something changes. Mine tranny has only 32K miles, but all the other components have 110K. I don't think it has a software problem because non of these cars hunted when they were 2-3 years old. Mobil 1 does the trick for me, but I still don't understand why.


<img src="http://pictureposter.audiworld.com/80919/dscn1028.jpg">

<img src="http://pictureposter.audiworld.com/80919/dscn1027.jpg">

tozoM8

There are a few differences between the two valve bodies, but the car runs with both. The 02 has one more check valve and some of the springs are different.

<img src="http://pictureposter.audiworld.com/80919/dscn1291.jpg">

ttuling

Tom

ttuling

Kind of surprising for a "lifetime" fluid.

That's one question answered with certainty!

Thanks,

Tom

ttuling

Do you have any ideas what could go wrong with LT 71141 to make the TCM think it should unlock the converter clutch when it just locked it? Even if the converter clutch grabbed very abruptly, the engine torque (or whatever guides lockup) should still be above the unlock threshold after lockup if the gas pedal hasn't moved. No matter what, right? If the TCM decides to lock, the act of locking should not change the data so much that it decides to unlock right after locking. There is enough hysteresis built into the system when new, and I can't see how fluid quality will reduce it. Not saying it's impossible, just that I lack imagination to come up with a scenario.

I'd enjoy comparing VAG-COM logs of engine torque and rpm, along with rpm across the converter clutch, as seen by the TCM in a hunting car and during light throttle lockup in one which doesn't. And also in a car which hunted before Mobil 1, so long as we're doing science.

I could believe degraded engine management sensors or even vacuum hoses causing the torque reading to get nonlinear in the crucial light throttle area, at least until O2 sensor feedback corrects it. I could see Mobil 1 synthetic, maybe lacking friction modifiers like those Mobil puts in their fluid for certain Aisin transmissions with deliberately slipping converter clutches, smoothing the lockup enough to keep the O2 sensors in control of the injector duration (which becomes the TCM's torque reading).

But I can't see how LT 71141 can make a correctly operating control system (sensors, ECM, TCM) correctly decide to unlock the clutch when it just locked it. And I will need to see that before I can blame the fluid and not something external for the hunting.

I'm not really saying anything new here, so will likely give it a rest. I don't think most cars' hunting can be cured at its root (as opposed to suppressed) solely by changing things inside the transmission, but will keep reading and don't mind being proven wrong. Best of luck,

Tom

ryoung

As much as anything else, I believe detergents keep assorted trash suspended and recirculating in the oil until it's removed by the filter.

Without detergents, I'd expect the assorted trash to settle out in all the low velocity nooks, corners, crannies, and passages ... which would eventually restrict flow thru critical passages.

skiracer

doesn't occur when the tranny is cold- the warm-up program seems to overcome any wear issues. Is there any way to fake the tranny into thinking it's cold without doing the same thing to the engine controls? I was also thinking that other items that have changed since these cars were new are the proviously investigated MAF but also the O2 sensors, the throttle position sensor, and any other electro-mechanical devices that the ECU/TCU uses to determine operating parameters. Perhaps the combination of wear in the tranny and wear in the various sensors combine to cause the behavior we are seeing. There may not be a single failure- it could be systemic.