[mdhopt36]

Talking with a mechanic at dealer's, they won't even talk about AFM cancel.

I want to know how to get rid of it.
In another thread, a guy remarked he got it tuned out.
AFM seems to be the instigator in the A* shudder, which is when I notice it the most.
Damn the warranty, I want that to go away.
Car will sound better after fuse pull, too.

What do I have to do to obtain this tune?
Thx,
M.

[arpad_m]

You should talk to a good tuner who has experience with TCM tuning.

That said and to answer your question directly, the AFM master disable switch is this one in the HP Tuners screenshot below, but I doubt this alone will be sufficient, you need a comprehensive trans tune to obtain the outstanding A8 operation you are after. At the very-very least the allowable slip amounts need to be set to 0, although that is not all there is to it.

[18ss376]

You have to buy 1 credit from HPtuners to unlock the FSCM & tune out the AFM valves.
This is way different than DOD which can be disabled in the ECM with HPtuners. The one above is just for DOD & not AFM.

[dmcmahan60]

I had the Range AFM disabler and it did not help the shudder problem. It actually made my situation worse so I removed the Range AFM.

[Mark114]

If you have the A8 shudder then I suggest you take it to the dealer to get the new flush with the latest fluid before you have it tuned. That will flush out whatever contaminates have collected and give you a fresh fill of the latest fluid.

https://www.camaro6.com/forums/showthread.php?t=527133

[mdhopt36]

Thx for the info. Made appt to dealer, but don't have a lot of warm fuzzy feeling. Think they're gonna try the "can't verify..." routine.

Setting allowable slip to zero-
What does that change? No slippage after moving?

[arpad_m]

Originally Posted by mdhopt36

Thx for the info. Made appt to dealer, but don't have a lot of warm fuzzy feeling. Think they're gonna try the "can't verify..." routine.

Setting allowable slip to zero-
What does that change? No slippage after moving?

Start here: https://www.camaro6.com/forums/showthread.php?t=510599

[18ss376]

Originally Posted by Mark114

If you have the A8 shudder then I suggest you take it to the dealer to get the new flush with the latest fluid before you have it tuned. That will flush out whatever contaminates have collected and give you a fresh fill of the latest fluid.

https://www.camaro6.com/forums/showthread.php?t=527133

This is correct for the A8 shudder, the OP is to disable the AFM valves. 2 completly different things, HPtuners will not fix the A8 shudder.

[KingLT1]

Originally Posted by 18ss376

You have to buy 1 credit from HPtuners to unlock the FSCM & tune out the AFM valves.
This is way different than DOD which can be disabled in the ECM with HPtuners. The one above is just for DOD & not AFM.

Those tables are for the NPP exhaust valves not AFM. Turning off DOD in the ECU disables AFM. If you remove the AFM valves due to replacing the X-pipe then you need to disable the AFM valve to keep from getting a CEL in the FSCM controller. Its the first switch in the list above the NPP valve tabs that you have open in the picture.

[arpad_m]

Originally Posted by 18ss376

This is correct for the A8 shudder, the OP is to disable the AFM valves. 2 completly different things, HPtuners will not fix the A8 shudder.

With all due respect, OP is talking about the A8 shudder and how to get rid of it via a tune. This is what we are addressing here. The FSCM change to clear the CEL after AFM valve removal was brought into this for no good reason.

HPtuners can actually be used to make TCM adjustments that fixed the shudder for several people, see https://www.camaro6.com/forums/showthread.php?t=510599 that I linked earlier for the initial idea from a reputable tuner.

Originally Posted by mdhopt36

Talking with a mechanic at dealer's, they won't even talk about AFM cancel.

I want to know how to get rid of it.
In another thread, a guy remarked he got it tuned out.
AFM seems to be the instigator in the A* shudder, which is when I notice it the most.
Damn the warranty, I want that to go away.
Car will sound better after fuse pull, too.

What do I have to do to obtain this tune?
Thx,
M.

[TJay74]

Originally Posted by arpad_m

With all due respect, OP is talking about the A8 shudder and how to get rid of it via a tune. This is what we are addressing here. The FSCM change to clear the CEL after AFM valve removal was brought into this for no good reason.

HPtuners can actually be used to make TCM adjustments that fixed the shudder for several people, see https://www.camaro6.com/forums/showthread.php?t=510599 that I linked earlier for the initial idea from a reputable tuner.

ARPAD is correct.

Turning off the DOD will help eliminate the shudder, also along with doing that if you zero out the TCC slip tables it will help as well. I have a 16 Sierra 6.2/A8 that I have turned the DOD option off since the truck was brand new. No shudder on the truck, plus I got rid of the TCC slip as well.

The AFM valves dont need any modification in the tune unless you are removing them from the vehicle.

[KingLT1]

^Agreed!

[mdhopt36]

Car went in yesterday, for a flush.
The maintenance clerk came out, said they couldn't replicate the issue.
Wanted to know if I still wanted the flush.
"yup, of course."
***
Asked me if I was gonna pay for it.
I said yes, i wanted it done.

So I asked him if he wanted me to take a mechanic up "depression hill" to prove it was shuddering.
He said the mech got paid a flat rate, etc.
OK, so I started to ask him if he knew there were issues with 8L90 and 8L45 trannies, and there was a lawsuit, etc.
He nodded.
I told him that -SOMEHOW, lawyers contacted me, I didn't call them.
***********
Anyhow, the flush took around 2.5 hours. i got to the counter to pick up my key, and he slid the receipt across the coubnter.
On the bottom of the BS on the sheet, it said-
NO CHARGE.

Well, that was cool, and somewhat a surprise.

But it burns my a$$ that he initially intended to make -ME- pay for it. He was a slick-talking bastard. This dealer is about the closest (convenient) but they're known to be shifty when it comes to service or warranty work.
I can tell the car is smoothing out, only put about 40 miles on it so far from leaving the shop.
The kicker, the actual mechanic that worked on the car opened his mouth, and said I should note a solid improvement after about 100 miles or so. These guys are fully aware of the situation with these trannies!

Many thanks for you guys, and the links you provided. Armed with all this info, I was able to turn this "screw-ing" to a rather pleasant outcome!!!

[ugxvibe]

As a trans tech at a GM dealer this is what I can tell you about the shudder.

1) The original DEXRON HP fluid was hydroscopic, meaning that it retains moisture much like brake fluid. This is causing the shudder. The new fluid formula does correct this.

2) The shudder only shows up in areas of the country that are humid. People in Arizona may never get the shudder for example.. GM pushed the tools to fix the condition first to the gulf state dealers.

3) In order for us to perform the flush under warranty GM requires us to verify the shudder with the Picoscope and attach a screenshot with the VIN to the repair order. Heck, I haven't even flushed my own Camaro yet because of this (it's not shuddering, yet) That fluid is very expensive and requires 20 quarts to get about all of the old fluid out.

Yes, we are all aware of the shudder but as always GM is having us jump through hoops with policy and procedures to save them money. The dealer would love to take GMs money, they just make it difficult. They aren't trying to screw you but cover their own butts.

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