6L90 1-2 shift very slow when cold

[Phillipm]

I've had my 6L90 and LY6 in my 1978 blazer for years. I've got 50k miles on it since putting it in. I've always hated how slow it shifts 1-2 when cold and my jerky 2-3 shift. Feels like the motor pulls a bunch of timing. I paid a trans tuner to fix it but have not gotten what I want out of that either. I've read a few threads but just not sure where to go. I even own the GM trans tuning book and that didn't offer me much help as its more performance based than trying to address what feels like TM?

Before I even attempt to make it shift a little firmer/quicker, I'd really just love to address the sloppyness.

Could someone take a look at the tune for me and get me off on the right track?

Should I log it with the TM type PID? anything else that would tell me where to start looking in the tune?

Thanks in advance!

Phillip

Blazer Tune 2021 Zero Gravity.hpt

[hjtrbo]

Stock tune if possible and a short log(s) capturing the events you described please.

[Phillipm]

Thank you for responding, and for all of your posts in this section.

Here is the stock tune and I will use those channels to scan the truck next time I have it home with me! It lives a few towns over at the moment.

[Cringer]

Thank you for responding, and for all of your posts in this section.

Here is the stock tune and I will use those channels to scan the truck next time I have it home with me! It lives a few towns over at the moment.

I am unable to open this file on HPT versions 3, 4, and 5. Maybe it is corrupt? Are you able to open it in the editor?

[Phillipm]

I am unable to open this file on HPT versions 3, 4, and 5. Maybe it is corrupt? Are you able to open it in the editor?

I just opened it on my PC now. I posted the file earlier from my Mac so maybe that's why? I'm running V4.10.5 of HP. Here it is again from my PC this time.

[hjtrbo]

I reckon go back to the stock tune, reset adapts then go from there. They've changed so much stuff. Crazy and not needed.

[Phillipm]

I reckon go back to the stock tune, reset adapts then go from there. They've changed so much stuff. Crazy and not needed.

OK Thanks. I will say it didn't always act like this on the 1-2 when cold. So maybe even resetting the adapts will help? For the jerky 2-3 (which has always been there) should I turn off the discrete torque on that gear only to try and help that? Anything else that I should focus on?

One thing that he did get fixed for me was, because this is in an old truck, any time I moved the shifter past Drive, it would go straight to second gear. He was able to manually add a second shift pattern for me but I'm not sure which shift schedule he's actually referencing for it.

I'll still try to scan the truck this weekend and post the log.

[hjtrbo]

Discrete shift might help. I'm surprised they enabled it for all gears. It does give consistent shift pressure per torque per enabled gear.

[hjtrbo]

I haven't had a good look at the tune. Just seen so much was changed. I'd like to see a wide open tune up through a couple of gears. Be interesting to see how it's shifting. Use those channels I have you. Make sure polling rates are set high of manually adding them.

[hjtrbo]

*run up through gears...

[Phillipm]

Thank you for your patience. Was able to get in the truck over the weekend and scan it. I was reminded that it's mostly the 2-3 shift that's very slow cold. So not only is it jerky warm its slow when cold. I later on tried to increase the Inertia Factor down low but that just made the jerky-ness faster. But, here is that scan:
I let it warm up for a bit so it really starts about 2:22. Then I did a full throttle up 1-5 at about 2:26 along with some light driving in between.

p.s. I did reset the adapts but it acted the same. Additionally the trans temp isn't working here but I deleted and readded that PID and it starting seeing it after I did that.

[Phillipm]

This is another scan after I raised the Inertia Factor from 1 to 2 in low torque areas. It honestly made things on/off/on during the shift and not smooth at all. Hard to explain I guess but it was definitely not moving me in the right direction.

Also in this scan around 2:50 I moved the shifter down one which selected pattern B, D5 on the PRNDL. This is something that Zero Gravity added for me. As before it would just go to 2nd gear if I put the shifter down to D5. I'm open to doing a write entire back to stock but does anyone know where I could access this to turn it back on if I do that? I don't see any D5 table options in hp.

I guess my goal is to just get it to be a smooth shift like a stock truck would be. I've owned this thing since 2016 and have yet to get this 6L shifting smoothly in all gears and crisp but not hard under WOT. Probably a lot to ask I guess.

[hjtrbo]

Before I open your logs, there are differences behind the scenes from the stock file not visible in the hpt editor. I presume zero gravity had you do a write entire?

The first thing I would try is return it to stock and run it for a few hundred miles just to see if the shift is nice. Admittedly it'll be factory soft and spongey but it's easier to tune from there than work backwards on what someone else has done.

No need to write entire just yet. Don't forget to reset / preset adapts. I'd leave these settings alone.


Use the compare utility to copy over the changes, will take about a minute.

[hjtrbo]

Yeah, definitely go back on the changes. Yuck

[Phillipm]

Yeah, definitely go back on the changes. Yuck

OK thanks. I've never really been super happy (even in stock form) but I'll go through the changes and set them back using the compare feature. I agree, I was going to leave those that you called out as well. What about the ratio did you highlight on the orange? is it that it's not settling into the gear and then looks like its fluttering around?

I've been reading as much as I can so I appreciate everyone's time.

[TransGo Robert]

I let it warm up for a bit so it really starts about 2:22. Then I did a full throttle up 1-5 at about 2:26 along with some light driving in between.

The shifts are definitely not nice, but I am curious here you wrote that you did a full throttle 1-2-3-4-5 but nowhere in your log are you ever close to going WOT. Most of the time it is at 15% during the upshift and once it goes up to 30% that's it. Was it maybe the wrong log that was sent? Oh and what do you mean by slow 2-3? Do you mean soft, long, or late shift?

[Phillipm]

The shifts are definitely not nice, but I am curious here you wrote that you did a full throttle 1-2-3-4-5 but nowhere in your log are you ever close to going WOT. Most of the time it is at 15% during the upshift and once it goes up to 30% that's it. Was it maybe the wrong log that was sent? Oh and what do you mean by slow 2-3? Do you mean soft, long, or late shift?

Hmm, I was definitely more than 30% TPS. I wonder if that channels was not being picked up correctly due to me loading that channel list. Next time I'm with it i'll reload that channel and confirm it's reading correctly.

It's too long (when cold) and and maybe marginally soft IMO. the timing is fine to me. I don't want this thing hitting gears hard and honestly if it would just work like you would expect a stock truck to work I'd be OK, i really don't mind the shifts being on the softer side. But I originally took it to ZG to work on the 2-3 and that shift has just never been that good (stock tune or ZG). And when i say not good, it's always had this feeling where the truck loses torque and puts it back on quickly leaving you with this jerky feeling. Additionally i remember on the stock tune it would also flare the 2-3 once or twice when cold.

Next plan will be to copy the stock parameters over and drive and rescan, but appreciate any additional thoughts.

[TransGo Robert]

Hmm, I was definitely more than 30% TPS. I wonder if that channels was not being picked up correctly due to me loading that channel list. Next time I'm with it i'll reload that channel and confirm it's reading correctly.

It's too long (when cold) and and maybe marginally soft IMO. the timing is fine to me. I don't want this thing hitting gears hard and honestly if it would just work like you would expect a stock truck to work I'd be OK, i really don't mind the shifts being on the softer side. But I originally took it to ZG to work on the 2-3 and that shift has just never been that good (stock tune or ZG). And when i say not good, it's always had this feeling where the truck loses torque and puts it back on quickly leaving you with this jerky feeling. Additionally i remember on the stock tune it would also flare the 2-3 once or twice when cold.

Next plan will be to copy the stock parameters over and drive and rescan, but appreciate any additional thoughts.

My guess is that it was the wrong log that was sent by accident. The maximum engine RPM for the first 9 series of upshift was only 2750 RPM, and then the 10th and last one at 30% throttle it shifted at 5800 RPM on the 1-2, but the maximum speed you reached was 64 mph and then you let go of the throttle just as it made the 3-4 shift and stared coasting down after that. It never made it to 5th under acceleration. In any event, yea that 2-3 shift is pretty bad. It is a lonnnng and uneven shift, the command is just bizarre to me. Not sure how to address that in the tune, I am on here to help with transmsision issues and at the same time learn about tuning as I am very green on that side of things. But it is definitely not commanding it properly, hopefully other guys' will be able to help you get it right and I'll get to look at the changes adn learn along the way.

[Phillipm]

My guess is that it was the wrong log that was sent by accident. The maximum engine RPM for the first 9 series of upshift was only 2750 RPM, and then the 10th and last one at 30% throttle it shifted at 5800 RPM on the 1-2, but the maximum speed you reached was 64 mph and then you let go of the throttle just as it made the 3-4 shift and stared coasting down after that. It never made it to 5th under acceleration. In any event, yea that 2-3 shift is pretty bad. It is a lonnnng and uneven shift, the command is just bizarre to me. Not sure how to address that in the tune, I am on here to help with transmsision issues and at the same time learn about tuning as I am very green on that side of things. But it is definitely not commanding it properly, hopefully other guys' will be able to help you get it right and I'll get to look at the changes adn learn along the way.

Sounds right. I was in a business district so could only get up to so fast. Previously it was mentioned to drive it a few hundred miles after the change. Is that so the adaptives can settle in?

[TransGo Robert]

Sounds right. I was in a business district so could only get up to so fast. Previously it was mentioned to drive it a few hundred miles after the change. Is that so the adaptives can settle in?

Yea, anytime you make changes you have to get them to adapt before you can really tell how they are working.