4L60E lock-up feel (LUF) solenoid info request

A forum for discussing applications and implementations of the MegaShift transmission controller code for the GPIO from B&G. This can control up to 8-speeds and 6 shift solenoids (plus a 16x9 table for controlling a PWM line pressure valve). It has manual and fully automatic modes (16x9 load x speed table), with under and over rev-limit protection, and full data logging of all inputs and outputs (among many other abilities). A TransStim to test your completed board is also available.
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Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

4L60E lock-up feel (LUF) solenoid info request

Post by Bernard Fife » Mon Oct 20, 2008 10:05 am

All,

Marc (ca434sbc) has let me know that In '98/99 GM introduced a new fluid circuit in the TCC to modulate the lockup, controlled by the lock-up feel solenoid (aka. LU Feel of LUF solenoid). Without this valve being driven the lockup is *very slow* and puts a lot of heat into the TCC clutch. They did it for 2 reasons: 1) to eliminate the lock up lurch, 2) allow a partial unlock for a bit more pulling power. It is grounded to activate (like the other 4L60E solenoids).

This source: http://www.zoom-tech.com/downloads/supp ... 5E-70E.pdf says that the LUF solenoid is a pulsed (PWM) solenoid with 0.0 – 1.8 Amps (Duty MIN - MAX) and a resistance (presumably DC) 9 - 14 Ohms. Lock Up is normally activated in 2nd, 3rd and 4th Gears. Lockup is activated in late models by energizing both Lockup and LUF solenoids.

If anyone has additional info, that would be great, things like the specific control strategies GM uses, the PWM frequency, the solenoid's inductance in milliHenries, etc. would be very helpful.

The initial plan is to use one of the 2 available spare outputs to drive the LUF solenoid, once we have it the strategy and limits clear.

Also, Marc noted that the 3-2 solenoid is there to speed up the band engagement on a 3-2 kickdown shift - and its only active above 35 MPH and low speeds its off. This is an off/on solenoid (on later 4L60Es, PWM on earlier models), but we can uses this with existing code simply by setting the PWM% to 100%.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw

ca434sbc4
Posts: 8
Joined: Sun Sep 14, 2008 8:43 pm

Re: 4L60E lock-up feel (LUF) solenoid info request

Post by ca434sbc4 » Tue Oct 21, 2008 7:40 pm

Lance,

I've talked to some good transmission guys, the PWM 3-2 valve on the early transmissions can be updated to the later on/off if the valve body separator plate is upgraded to a trans go part see this web page for details... http://www.transgo.com/separatorplate.php <<<< I've used these plates with good success.

GM tried to make the 3-2 downshift smoother by modulating the 3rd accum release rate.... my guess is they ended up with a bunch of burnt 2-4 bands in the process.

An easy way to identify if a trans has the PWM LU - with the trans out of the vehicle or if your lucky with the inspection cover off - remove torque converter/look at the outside of the front pump - if its says PWM in the casting -its got the updated fluid circuits.

Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: 4L60E lock-up feel (LUF) solenoid info request

Post by Bernard Fife » Wed Oct 29, 2008 12:11 pm

Marc,

Thanks, that's good info.

I still need to sort out the logic for the LU Feel. Things like:

- is the LUF solenoid on at all times, or is it active only when the torque converter is locking? If so, how does the ECU know how long it takes to lock the converter (for example, does it have a table stored to tell it this - seems unlikely given tolerance and wear issues - or does it compare engine rpm to input shaft rpm - neglecting slippage in the gears)?

- what are the acceptable ranges of PWM% for this function? Can it be 0% to 100%, or is it 30% to 100% or .... ?

- what is the preferred PWM frequency? GM likely has an optimal frequency they like to drive the solenoid at, and I would like to duplicate that as much as possible.

- are there restrictions on when this solenoid must be on? must not? (Things like greater than a specific mph, only certain gears, etc..)

You mentioned (privately) an 8x8 table of LUF PWM% by rpm and MAP. I could certainly implement this, but it would be nice to fit it into the context of the answers to the questions above.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw

ca434sbc4
Posts: 8
Joined: Sun Sep 14, 2008 8:43 pm

Re: 4L60E lock-up feel (LUF) solenoid info request

Post by ca434sbc4 » Wed Oct 29, 2008 9:00 pm

See below..
Lance wrote:Marc,

Thanks, that's good info.

I still need to sort out the logic for the LU Feel. Things like:

- is the LUF solenoid on at all times, or is it active only when the torque converter is locking? If so, how does the ECU know how long it takes to lock the converter (for example, does it have a table stored to tell it this - seems unlikely given tolerance and wear issues - or does it compare engine rpm to input shaft rpm - neglecting slippage in the gears)?

The LUF is active when the TC needs to LU, I believe the %DC is based on load, map/rpm. You may be right that they look at slip.


- what are the acceptable ranges of PWM% for this function? Can it be 0% to 100%, or is it 30% to 100% or .... ? GM runs it at 30-95% DC

- what is the preferred PWM frequency? GM likely has an optimal frequency they like to drive the solenoid at, and I would like to duplicate that as much as possible. << good question - anyone have access to late model truck to do a measurement?

- are there restrictions on when this solenoid must be on? must not? (Things like greater than a specific mph, only certain gears, etc..) Its active in 2,3,&4 to the best of my knowledge.

You mentioned (privately) an 8x8 table of LUF PWM% by rpm and MAP. I could certainly implement this, but it would be nice to fit it into the context of the answers to the questions above.

Lance.

Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: 4L60E lock-up feel (LUF) solenoid info request

Post by Bernard Fife » Thu Oct 30, 2008 12:10 pm

Here's bit more background info I dug up at http://www.patentstorm.us/patents/71042 ... ption.html:
The present invention relates to the field of hydraulic circuits within automatic transmission systems and, more particularly, to a replacement torque converter clutch (hereinafter "TCC") regulator valve that reduces fluid pressure loss to the torque converter apply and release circuits, which actuate the torque converter clutch.

The General Motors 4L60-E (hereinafter "GM") transmission and other similar GM transmissions are equipped with mechanisms to "lockup" their torque converters to varying degrees under certain operating conditions. The purpose of the lockup converter is to provide for direct drive when the vehicle is cruising at higher speeds. Since there is always some slippage in the fluid coupling of a torque converter, some power is lost and fuel economy suffers. By providing a direct mechanical coupling through the transmission at high engine speeds, the lockup converter improves fuel economy.

This is accomplished by an electronic/hydraulic torque converter clutch system, which utilizes a lockup piston within the torque converter housing. The lockup piston has friction material on its forward surface. When the vehicle is at cruising speed and lockup is desired, an electric solenoid is energized which opens the torque converter clutch (hereinafter "TCC") regulator valve. This allows fluid pressure to act upon the lockup piston, which is forced against a machined surface on the converter cover. Thus, the lockup piston and the converter cover are locked together and act as a single unit similar to a manual transmission clutch. When lockup is no longer required, a port opens that allows the pressurized fluid to exhaust. The lockup piston then moves away from the torque converter housing re-establishing the fluid coupling.

Early 4L60E transmissions utilized 2nd gear clutch fluid, which was essentially line pressure applied via an orifice, to actuate the TCC regulator valve. In this version of the transmission, the TCC regulator valve and the isolator valve were combined into one valve. In later versions lockup in the electronic torque converter clutch system was controlled by a pulse width modulated torque converter clutch (hereinafter "PWM TCC") solenoid that provides an output or control pressure in response to the duty cycle imposed on the solenoid coil.

In 1993 General Motors converted to the PWM actuated TCC regulator valve and divided it into two separate valves, namely the regulator apply valve and the isolator valve. Thus, in the PWM versions (1993 1997) of the 4L60E torque converter, there are actually two converter solenoids being employed in the system. The PWM TCC solenoid sends automatic transmission fluid (hereinafter "ATF") to the isolator valve. Since the PWM TCC solenoid is duty-cycling the isolator valve, it oscillates continuously within the valv body. The regulator apply valve receives line pressure and regulates it to a lesser pressure, which is known as converter apply pressure. Converter apply pressure is not actually sent to the torque converter, but to the TCC apply valve. The TCC apply valve is actuated by the TCC solenoid. This solenoid is simply an On/Off type solenoid and not a PWM type. It is the TCC apply valve that actually directs ATF to the torque converter.

In 1998 General Motors went to the "EC3" style torque converter. This design allows the torque converter to continuously slip from 2nd gear upward without ever locking up completely. This design was intended to improve fuel economy and converter control. The regulator apply and isolator valves were changed only slightly and function exactly the same as the 1993 1997 PWM version.

A disadvantage associated with these systems is the pulsating flow generated by the pulse width modulated TCC isolator valve as it cycles between its open and closed positions. The isolator valve imparts some of this pulsating movement to the regulator apply valve. These pulsations cause wear within the valve body resulting in hydraulic fluid leakage and incorrect pressure responses. As a result vehicles with a 4L60E transmission often have insufficient TCC apply pressure causing uncontrolled clutch slippage, which overheats the converter and generates TCC slip codes requiring service work. These complaints can often be caused by ATF leakage past the TCC regulator valve resulting in reduced converter apply pressure.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw

Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: 4L60E lock-up feel (LUF) solenoid info request

Post by Bernard Fife » Wed Nov 12, 2008 4:06 pm

All,

In the absence of complete info on the TCC lock-up feel solenoid functioning, I have added a TCC PWM general function to the code.

The LUF function is selected in MegaTune under 'Shift Logic Patterns/Configure Lever Type and Clutch Outputs/Spare Port Usage' where you select 'Use PWM2/Amp32 for LUF and SPR2/PA0/VB2 for TCC'.

This uses the TCC output for the PWM, and SPR2 for the on/off TCC output. The switch was necessary because only pins 0-5 of the timer ports are available for PWM use. Spare output 1 remains available for general use, but SPR1 cannot be used as a 'clutch' out (i.e. one that only is active during shifts).

The PWM frequency can be user set, under 'General Settings/Solenoid PWM Setup/TCC PWM Period'. The default is 32Hz (31.25 milliseconds).

There are 4 user parameters for setting the PWM percentage, a low load, a high load, and the PWM% at each. When the current load is below the low load, the low load % is used, and above the high load, the high load % is used. Between the low and high load, the value is linearly interpolated. Note that the % can be high at low loads and low at high loads, or vice versa:

Image

There is also a PWM% setting for when the TCC is not engaged. It can be 0 for off, or any percentage from 0 to 100% (100% being fully on when the TCC in unlocked, of course). The defaults have been set at 0% when TCC is off, 30% at 50 kPa, and 95% at 100 kPa;these are the 4L60E defaults (as best we know). The LUF PWM% is updated 100 times a second when the TCC is engaged.

Hopefully that will cover most situations (and might be useful to people who want a load based PWM output for other purposes).

I have only done rudimentary testing of this so far, but will post the code for people to play around with. It is a zip file of the MT project folder, the S19 file in there as well.

On a related note, the code is approaching the 32K limit, so adding many more developments will likely mean users will have to strip some code out if they want to mod and compile the code on the free special edition of Codewarrior.

Lance.
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"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw

Philip Lochner
Posts: 34
Joined: Thu Mar 08, 2012 9:00 am

Re: 4L60E lock-up feel (LUF) solenoid info request

Post by Philip Lochner » Sun Jul 12, 2015 12:34 pm

I have posted some info in this thread, hoping it may be of value: viewtopic.php?f=4&t=930#p5467
Best regards
Philip
'80 Jaguar XJS 5.3L V12 = MS-2
'74 Jensen Interceptor Mk3 440 V8 = MS-2 + GPIO (GM 4L60e)

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