Will the fast relearn work on a 8l90? If so, what's the proper procedure?
Will the fast relearn work on a 8l90? If so, what's the proper procedure?
Yes, I've used it a couple times. It does help with the jerking from P to D and M.Originally Posted by dave01gt
First add the fast relearn PID to HP Tuners and monitor it. It will be updated with the status of what to do and when complete or aborted.
Transmission fluid temperature must be between 167?F (75?C) and 185?F (85?C).
With the engine running, shift the transmission to the Drive position with the brake applied.
Perform the Service Fast Learn procedure.
It takes about 5 - 8 minutes with my Corvette.
Turn car off for 2 minutes or more.
Done.
Are you saying I can initiate a fast learner with HTP? I was under the impression that I needed a dealer tool for that. If I don't, that would make my day.
yes, HPT has this feature.
I have tried this a few times in my Camaro SS with the A8. I can never get it to work fully. When i get the trans to temp (takes forever) and start it , it starts the ?Learning D? and continues to jerk the hell out of the car over and over until it finally goes to ?abort?. My TCM is unlocked and tuned if that has anything to do with it.
Anyone know what is causing this?
You might perform global reset by removing battery cables and touching together. This will power down all modules. Then perform fast learn. Start cold and power torque in reverse for quickest warm up to 75c or a few degrees below. Then put in drive. Don't let off brake until complete. I've seen temps over shoot range and abort. Have had to run with external fan on some too cool to prevent overshooting temps during fast learn. Have performed at dealer 100 plus times with Cadillac Escalades and sedans. Not sure how refined process thru HP Tuners, but may very well wind up at dealer if you can't get performed. Have also had to program TCM, then perform fast learn. Depending on year, there are likely factory TCM updates ,flushes, and even some new torque converters to correct TCC chatter and shifting issues. I know more info than you needed, but just telling you my experience in the dealer world.
There is also an extensive drive cycle to relearn clutch fill rates and times. This is done in manual mode at specific rpm to force relearn. One can drive and eventually learn all gears, but this will take much longer.
Send me email and I'll send you a bulletin for the process.
I have took it to the dealer for the triple flush when i first started experiencing the infamous shudder the 8l90 has. The shudder is gone thanks to the tuning I had done. But now that I am tuned, the shifts from park to reverse and park to drive, as well as between reverse and drive are very rough and clunky.
It now is also clunky on some downshifts. I think I fast relearn would help but I cannot get it to execute fully. Thanks for the info will give it another go. Last time I tried it kept violently jerking in driving while HP tuners read ?learning D? . Is this what it should be doing when learning d?
It is usually not too violent but I have had a few wild ones. Basically the computer is commanding different amounts of throttle while testing how much pressure is required to get certain amounts of clutch application/RPM drop.
Yes, it will sound like metallic snapping inside trans and jerky. Sounds like something may break inside trans.. This is all normal. Definitely set parking brake and you may want to double foot brake. Towards the end it may seem like nothing is happening. Just continue to hold brake and let it finish. It could take up to 10 minutes. If you let off brake, then you are going to start over. It will abort. After finishing, shut ignition off , open and close door, and wait for 3 minutes or you will have no gears when you re-start. Then drive like the bulletin states to refine the "problem" shifts. Driving in a specific manual gear at a steady rpm listed in bulletin will force into learn mode for that gear. That's why it takes so long to learn all the gears in. Good luck.
Last edited by DGS; 11-24-2018 at 11:34 AM.
Hi sorry for hijacking this thread , i have the Lt4 / 8l90 connect and cruise package fitted i a 55 chevy and tried to do the fast relearn but the problem i have is that there is no connection between a brake switch and the ecm (no wire designated in the Gm provided Harness) so it does not get the needed brake pedal signal
does anyone know wich connector and pin # i need for the brake signal and how to wire ? does it need a 12v feed when braking or the other way around ?
or is there another way to perform the Fast learn.
thanks Sander,
did some more searching on the wiring reading the instruction sheet supplied with the engine and transmission
i only found the mention of top of travel clutch/brake switch 2 wires but no explanation on how to hook the up ?
see attachments these 2 wire go to the Ecm connector 1 on pin 64 and 67
i hooked up a switch to these 2 wires but it does not react while trying to perform the Fast relearn the status stays on apply Brake and after a while it aborts
the issue i am having is when i select from Park to R or from N to R it realy shift harsh into Reverse with a ''Clunk'' this just started suddenly i have test driven the car for about its first 150 miles and performed like a dream
since this came up, i also noticed it does not down shifts from 3rd to 2nd and starts to stall or down shifts realy late.
https://drive.google.com/open?id=1iU...vDwvVkdoR2hC0Y
https://drive.google.com/open?id=1iZ...KjMAqwLee-bPs9
https://drive.google.com/open?id=1iQ...a5u61j24m7wxWD
Can relearn process be done without purchasing credits ?
Yes
after you done with the process do you still have to drive the vehicle for clutch learn? i mean like it say in the bulletin? thanks.
The fast learn process is not perfect but for people that suffer harsh shifts it can improve their situation by getting rid of old shift data that might not include enough light/no throttle accel/decel up/downshifts and starting over with the basics that the computer can learn while sitting with the brake on. As the bulletin says (if I remember right) if a certain shift is still harsh you can basically run it through that shift over and over until the computer figures out how much pressure is needed and how fast to apply it. This step is rarely needed.
Hi Guys, quick help please!
i have done the fast relearn procedure twice with my camaro 8 speed transmission 8l45, now i am doing the recommended procedure by GM without any tool, could you guide me what does this mean,
Copied from gm doc,
Further Learns:
? Complete 15 light throttle 6-7 upshifts at approximately 15% throttle to further learn.
Does this mean i have to shift from 6th gear to 7th gear 15 times on lite throttle approx 1.5rpm?
What if i shift to 7th gear i can go back to 6th gear and do the same steps 15 times?
After doing the fast relearn, the manual procedure you are describing is not needed.
Appreciated your reply,
I see no change unfortunately in downshifts it is still harsh
I get kind of buck/jerk when its coming to stop and coming down from 5th to 4th only rest all seems to be fine.
I am not an expert i paid twice to dealership to do fast-relearn.
Please your suggestions will be highly appreciated.
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