Question about having PCM Tuned

[snoozer]

I am getting ready to have a PCM Tune to remove fan codes on my 2003 Trailblazer & I was wondering if having the following done will shorten the life of the transmission, turn off torque management & turn off PWM torque converter engagement?
I do most of my driving is city driving with some highway & no towing.

Thanks
Mark

 

[Reprise]

If anything, you might be *extending* the life of your trans. Here's why...

Torque Management allows for nice pillow-soft shifts. Lots of people like a soft (even imperceptible) shift - but to get that, friction is introduced - and friction creates more wear. You'll feel the shifts more as a result, by disabling it, but there will be less slippage / friction. IIRC, Torque Mgmt adjusts the shift by manipulating the throttle response.

I'm actually having Lime-Swap flash my PCM as well - sent it off today (but I'll have to wait a week because Jeremy's going on vacation). I mention this because I had sent him a note a few months ago with some questions & to give him some background of what I was looking for - he was happy to provide recommendations on Torque Mgmt & other parameters as well.

The nice thing is, if you don't like the changes, it can always be flashed again (although there's a $25 charge for doing so - you probably saw that on his website.)

Turning 'off' PWM engagement can have an even greater benefit for trans longevity than adjusting Torque Mgmt. PWM is used to engage torque converter 'lockup', and also has a role in shift 'quality' - but it does this via a 'TCC' valve that tends to wear in its bore, and by continuously 'slipping' the torque converter. Slipping = friction = wear (sound familiar?)

Many people on this forum (myself included) have installed corrective shift kits in order to guard against / correct the TCC valve issue above. So you're doing much the same thing, only via software. Now, if it's actually being turned 'off'... I don't know what that will do for 'lockup' on the Torque Converter - when you get into lockup, you're running the engine about 300 or so RPM lower than it normally would in 4th gear - which helps with fuel economy. So if it's 'off' - will you lose TC lockup altogether? (I'm not sure)

The shift kits I mention above turn it into an 'on / off', where lockup winds up feeling like a 5th gear - and we can kick it right out of lockup as well (ex: engaging passing gear, or closing the throttle outright / braking.)

Our kits eliminate the 'pseudo-lockup' in the higher gears, which is what happens with the stock setup - the vehicle goes continuously into / out of lockup as road / load conditions dictate. That is eliminated with our shift kits, but we can still get into lockup at steady state cruise in 4th gear. Hopefully, you can do the same, via the flash.

Worst case if you lost lockup entirely is that you might lose 1 mpg or so if you're taking a longer highway trip. While I'm happy to have control over lockup, if it were a choice between "losing it altogether and taking a small MPG hit" and "having it but putting more wear on the trans", I'll pick the first scenario..because for what it costs to rebuild / replace a trans,...you can buy a LOT of gasoline.

I notice you say your usage is 'mostly city'. If it's stop / go, or even stoplight to stoplight - the best thing you can do to make the trans last longer - is an external transmission cooler. They cost about the same as a tune, and are a lot cheaper than rebuilding a trans. Outside of that, your conditions don't sound too bad (e.g.; no towing, doesn't sound like you drive too aggressively, etc.) Also, if you're stoplight-to-stoplight - you probably don't get the chance to even get your TC to lockup, as I've been writing about above.

Anyway, let us know how you like your tune when you get it back. As I mentioned above - I just sent my PCM out for a tune (mostly for fan codes, but also to 'wake up' the throttle response - which you should notice as well, if you're having Torque Mgmt eliminated outright ('0%')).

 

[snoozer]

If anything, you might be *extending* the life of your trans. Here's why...

Torque Management allows for nice pillow-soft shifts. Lots of people like a soft (even imperceptible) shift - but to get that, friction is introduced - and friction creates more wear. You'll feel the shifts more as a result, by disabling it, but there will be less slippage / friction. IIRC, Torque Mgmt adjusts the shift by manipulating the throttle response.

I'm actually having Lime-Swap flash my PCM as well - sent it off today (but I'll have to wait a week because Jeremy's going on vacation). I mention this because I had sent him a note a few months ago with some questions & to give him some background of what I was looking for - he was happy to provide recommendations on Torque Mgmt & other parameters as well.

The nice thing is, if you don't like the changes, it can always be flashed again (although there's a $25 charge for doing so - you probably saw that on his website.)

Turning 'off' PWM engagement can have an even greater benefit for trans longevity than adjusting Torque Mgmt. PWM is used to engage torque converter 'lockup', and also has a role in shift 'quality' - but it does this via a 'TCC' valve that tends to wear in its bore, and by continuously 'slipping' the torque converter. Slipping = friction = wear (sound familiar?)

Many people on this forum (myself included) have installed corrective shift kits in order to guard against / correct the TCC valve issue above. So you're doing much the same thing, only via software. Now, if it's actually being turned 'off'... I don't know what that will do for 'lockup' on the Torque Converter - when you get into lockup, you're running the engine about 300 or so RPM lower than it normally would in 4th gear - which helps with fuel economy. So if it's 'off' - will you lose TC lockup altogether? (I'm not sure)

The shift kits I mention above turn it into an 'on / off', where lockup winds up feeling like a 5th gear - and we can kick it right out of lockup as well (ex: engaging passing gear, or closing the throttle outright / braking.)

Our kits eliminate the 'pseudo-lockup' in the higher gears, which is what happens with the stock setup - the vehicle goes continuously into / out of lockup as road / load conditions dictate. That is eliminated with our shift kits, but we can still get into lockup at steady state cruise in 4th gear. Hopefully, you can do the same, via the flash.

Worst case if you lost lockup entirely is that you might lose 1 mpg or so if you're taking a longer highway trip. While I'm happy to have control over lockup, if it were a choice between "losing it altogether and taking a small MPG hit" and "having it but putting more wear on the trans", I'll pick the first scenario..because for what it costs to rebuild / replace a trans,...you can buy a LOT of gasoline.

I notice you say your usage is 'mostly city'. If it's stop / go, or even stoplight to stoplight - the best thing you can do to make the trans last longer - is an external transmission cooler. They cost about the same as a tune, and are a lot cheaper than rebuilding a trans. Outside of that, your conditions don't sound too bad (e.g.; no towing, doesn't sound like you drive too aggressively, etc.) Also, if you're stoplight-to-stoplight - you probably don't get the chance to even get your TC to lockup, as I've been writing about above.

Anyway, let us know how you like your tune when you get it back. As I mentioned above - I just sent my PCM out for a tune (mostly for fan codes, but also to 'wake up' the throttle response - which you should notice as well, if you're having Torque Mgmt eliminated outright ('0%')).

Thanks for the information. I really appreciate it.
I have a loaner PCM coming Tuesday or Wednesday, can't be without the truck.
I was just kind of questioning my changes that I was having made after ordering.
I am new to vehicles with computers, but not cars & trucks used to be a mechanic years & years ago.
I know in the past I used to install shift kits in transmissions & it kind of sounds like some of this can be handle with a PCM tune instead.
You suggested a transmission cooler, any particular one that you like compared to others?


Once again thank you
Mark

 

[Mooseman]

@Reprise 's info is bang on on TCC lockup.

You did ask about torque management. I think the idea behind that is to lower shock load on the drivetrain by overzealous drivers. This is basically how it works and when it's tuned out:

It's your choice. Most tuners say to leave some in if you tow but in the old days of carburetors, torque management was our foot so I call BS. It's something OEM's added to just marginally lower warranty returns at no cost to them.

 

[snoozer]

@Reprise 's info is bang on on TCC lockup.

You did ask about torque management. I think the idea behind that is to lower shock load on the drivetrain by overzealous drivers. This is basically how it works and when it's tuned out:

It's your choice. Most tuners say to leave some in if you tow but in the old days of carburetors, torque management was our foot so I call BS. It's something OEM's added to just marginally lower warranty returns at no cost to them.

So that's why it seems so sluggish during take off. I mean it's not real bad just not what I am used to.
I think I might have made the right choice then on having it tuned out.
Looking forward to the tune.
Thermal fan clutch made a big difference in itself.
Thank you for video & your thoughts on this.

 

[xavierny25]

Just to add my . Your loaner should come preset with the tune you want for your truck. Well thats what limeswap did for me.This way you'd be able to go back and call if you want something changed or set back before yours ships back to you. I was very happy what he set me up with and it's a whole lot nicer to drive now.

 

[Reprise]

So that's why it seems so sluggish during take off. I mean it's not real bad just not what I am used to.
I think I might have made the right choice then on having it tuned out.
Looking forward to the tune.

Yep...so am *I* ... I have to wait a few more days till I get mine back, tho.
Watching that vid that Moose linked to...I'm expecting *much* improved throttle response

 

[snoozer]

Yep...so am *I* ... I have to wait a few more days till I get mine back, tho.
Watching that vid that Moose linked to...I'm expecting *much* improved throttle response

Just installed the loaner PCM this afternoon, haven't drove it yet, but going to in the morning. From what xavierny25 says it should be setup like mine will be after sending it in.

 

[xavierny25]

@snoozer how's that tune working for you?

 

[Reprise]

FWIW, I'm supposed to get mine back tomorrow, according to the post office.

Finally finished all of the fan clutch / water pump / belt / alternator updates today, so I'm ready to pop it in, run the training sequence (I moved my air inlet valve by hand, which I found out was a no-no, so it may be out of alignment with the TPS), and evaluate the updates that were done. Fingers crossed

Provided everything runs well afterward, I can start writing the 'how-to' for this process next week, after I return from downstate.

And, I even got $50 back from Lime-Swap - I had sent $149, and GMT360s / 370s continue to cost only $99, whether I6 or V8. Go get some!

 

[snoozer]

@snoozer how's that tune working for you?

Sorry it took me a bit to get back to you. Been a busy week,
What can I say best money I have invested lately.
So much more responsive, you hit the gas & it goes & I mean it goes.
At times I forget it is a 6 cylinder.
Combination of removing electronic fan clutch & the PCM tune has made my Trailblazer run 100 percent better.

 

[Reprise]

Same from my end, as described in my other post yesterday. I didn't have to train the TPS, nor did I have to do the PCM relearn.

The only bad thing that happened is that my vent actuator flaked out again - which is going to suck on a 6hr drive tomorrow, if it doesn't come back (it has every time before, although I can't predict 'when').

Thankfully, I don't have to disconnect the battery that often (next instance will be when I work on the stereo - and that will be the perfect time to do the actuator.)

Yes, I know I should replace it. It's on my "Envoy to-do list", but a bit lower in priority, compared to the mechanicals that I still want to work on before winter hits -- I want to make the Voy my DD through the winter months this year.

Checking my rad today, it's as full as I filled it - nothing lost. But the reservoir is empty (which is a little worrisome. I'll fill it again before I start it up - and will be taking some coolant with me, 'just in case'). No evidence of leakage that I see.

 

[Mooseman]

The only bad thing that happened is that my vent actuator flaked out again - which is going to suck on a 6hr drive tomorrow, if it doesn't come back (it has every time before, although I can't predict 'when').

Maybe try pulling the HVAC-B fuse for a bit to do the actuator relearn. Might work. Just don't touch anything during the relearn.

 

[Reprise]

That's a great idea - I will try that tmrw (my cargo area is full up until tmrw morning.) My control head seemed a little 'off' as well; maybe that will take care of both items. Thx for the suggestion; )