Negative effects of a tuner, and supporting mods?

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mattsmall1972

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Matt, how much did the MPG go down with the AFM delete? Thinking about it but curious as to the MPG.
Thanks, Keith
I have a hard time saying because my foot is more in the pedal now that it used to be. :)

Edit: I am about to get a tune. I want to sell my AFM module and if you want to, I'll send mine to you to test and you can buy it if you like it or send it back.
 
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I added a HyperTech tuner that eliminated AFM below 50mph and gave me a half dozen option on trans shift points and firmness. The shift adjustment was a huge plus for me and I don't see anything as far as mileage loss.
 

16rgs

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I have a hard time saying because my foot is more in the pedal now that it used to be. :)

Edit: I am about to get a tune. I want to sell my AFM module and if you want to, I'll send mine to you to test and you can buy it if you like it or send it back.

Matt, how much would you want for it if I liked it? Really couldn't go wrong with the offer? What MFG? Thanks, Keith
 

drakon543

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only downfall of a tuner is worse mpg until you get done playing with the extra pep and go back to driving it normal. basic intake and exhaust upgrades benefit more when combined with a tune but aren't necessary. hypertech is nice and simple but its mostly designed for stock everything. i would suggest getting an updatable tuner see what you think if you want more start doing the intake and exhaust and change the tune. if you have the cash to burn do the intake and a catback exhaust and the tune.
 

noob

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I'm curious, It seems like my torque converter shudder started to develop AFTER I decided to drive my car hard at ~30k miles. I'm wondering with the more aggressive shift points, it was cause the shudder to come back quicker.
 

CMoore711

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I'm curious, It seems like my torque converter shudder started to develop AFTER I decided to drive my car hard at ~30k miles. I'm wondering with the more aggressive shift points, it was cause the shudder to come back quicker.

I'm no tuning expert and I couldn't write a TCM tune... However, I do know that most TCM tunes do a handful of things to increase the performance of the transmission. Most of those things include but are not limited to:

1. Reducing Torque Management - Which can lead to harsher interaction between your transmission's hard parts.
2. Increased Line Pressure - Provides quicker firmer shifts.
3. Slightly raised shift points - multiplies the impacts of 1 and 2 above (in regards to the transmission).

Now, the above are not necessarily bad things or bad for your transmission if implemented in moderation, most auto enthusiasts don't complain about the increased performance of their vehicle after a tune. And the factory GM settings on the 8-speed definitely leave a lot to be desired. To your point, if you have any sort of potential weak part, problem that has a band-aid on it, or a part that is wearing prematurely a performance tune will exploit it.
 

noob

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I'm no tuning expert and I couldn't write a TCM tune... However, I do know that most TCM tunes do a handful of things to increase the performance of the transmission. Most of those things include but are not limited to:

1. Reducing Torque Management - Which can lead to harsher interaction between your transmission's hard parts.
2. Increased Line Pressure - Provides quicker firmer shifts.
3. Slightly raised shift points - multiplies the impacts of 1 and 2 above (in regards to the transmission).

Now, the above are not necessarily bad things or bad for your transmission if implemented in moderation, most auto enthusiasts don't complain about the increased performance of their vehicle after a tune. And the factory GM settings on the 8-speed definitely leave a lot to be desired. To your point, if you have any sort of potential weak part, problem that has a band-aid on it, or a part that is wearing prematurely a performance tune will exploit it.

That's pretty much what I was thinking, Though everything would be "better", wear would be increased due to harder shifts and more pressure which would exacerbate the poor design of our 8 speed transmissions.
 

CMoore711

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That's pretty much what I was thinking, Though everything would be "better", wear would be increased due to harder shifts and more pressure which would exacerbate the poor design of our 8 speed transmissions.

I haven't quite bought into the whole "poor design of the 8 speed" just yet, I realize that's somewhat of a common perception/opinion on this site, maybe because I come from a Trailblazer SS that had a 4L70E. I know the 8L90E has had some issues and things that have or need to be addressed with TSB's etc. but what automatic transmission hasn't? The current 10 speed has had similar issues, hell there are forum members with '18+ Denali's experiencing the "rumble strip" symptoms of the TCC issue and getting a similar TSB done on their 10 speed to fix it as often required on the 8 speed.

Additionally, GM is still putting the 8 speed into many current vehicles; the Camaro SS/ZL1, Corvette Stingray/Grand Sport/ZO6/ZR1, Cadillac CT6, ATS-V, CTS-V, XT5 to name a few. If the 8 speed were that much of an abomination and "failure" GM would stop using it.
 

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