8L90 minimum driving rpm

[vet57air]

Am a newbie here. Have a 2019 LT4 8L90 connect and cruise package in my 66 C10. Since I've been on the road I noticed that the driving rpm's seem low. Works well otherwise. Driving around at 30 mph in auto rpm is 1000. Stays there until your on the highway and in 8th gear and goes up with speed. Speedo was good out the gate. I used the Gear/tire wizard to input my 3:73 gear and 31" tall tires with no real change. I have searched on how to increase minimum driving rpm many ways with nothing found. Looking for guidance.

[5FDP]

If you don't like it shifting up so many gears and basically lugging the engine, you can just increase the mph shift speeds.

I do that on all the 6 speeds because it will shift into 6th gear below 40mph if you let it.

[vet57air]

If you don't like it shifting up so many gears and basically lugging the engine, you can just increase the mph shift speeds.

I do that on all the 6 speeds because it will shift into 6th gear below 40mph if you let it.

Sounds super. But I have no idea where that is? Can you give me a hint?

[blindsquirrel]

Sounds super. But I have no idea where that is? Can you give me a hint?

Not if you don't post your file so we can see what you see.

[vet57air]

Hope I did this right. I see normal part throttle shifts and throttle position? Is the coloured portion mph? What are the pattern A and B used for? 7-8 shift after 56% 272 mph, why would they do that, I can't go that fast, LOl ?


LT4 8L90 tire gear change.hpt

[5FDP]

That's what you should be seeing.

In the shift scheduling tab, that is where you can adjust the shift speed. The normal upshift table is showing you what MPH the shift can happen at, at a given throttle percent.

Just start pushing the MPH up at the lower throttle percents and it'll be a lot better. Like for example it has the 5-6 shift under 25% throttle at a pretty low MPH of 32. You can raise that speed to say 40mph or whatever to match the 25% throttle. Then just work the rest of the cells so it's a smooth transition as throttle percent increase. After the upshift stuff is done you can go to the downshift table and increase those speeds a little bit as well.

It's trial and error to get things how you want them.

[vet57air]

Thankyou. Thinking I don't need big changes to be happy. Do I need to consider converter lockup table or should it be fine?

[vet57air]

So I have read my LT4 8l90 in my 66 Cgt. I have previously used the tire/gear wizard to change my tire size and rear gear ratio in scanner mode. Read two ecu's and gave me two files. I have modified the part throttle shift schedule and am ready to write. Expected to be instructed to buy credits, which it did. Showed a E92 ECM. "Do not license" was highlighted and my controller serial # with 2 credits needed was greyed out. 1) is it greyed out because I am not plugged into vehicle? 2) If 1st question to true, once I buy the credits and plug in to vehicle will I be able to make the changes to the transmission? Would rather not pay for credits if I can't use.

Playing around I noticed in the tire wizard in editor there is auto scale. I tried the manual scale and set the multiplier for 1.15 and low and behold the normal shift tables along with a few more tables all changed all more to my liking. Is this a better way to do it?

[blindsquirrel]

Read the ECM & TCM at the same time and it will save both in a single file.

[vet57air]

I reread both E92 and T87 and this time it allowed me to place in one file. Made changes to part throttle shift schedule and went to write to vehicle (connect and cruise LT4/8L90). Got message to buy 2 credits for E92, but doesn't mention T87. I only need to make changes to trans shift points, will it work or would I be buying credits for nothing?

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[vet57air]

Figured it out all by myself. Now to get the shift points right.

[vet57air]

I am raising part throttle shifts. It maybe a "connect and cruise" thing, but the normal part throttle shift tables don't seem to be used. Took me a couple of tries to realize. Not wanting to try Pattern a and b and hot trans tables separately I copied and pasted my work to them. From the start they were all the same as the normal anyway. Now I have some decent auto shifts.