Thread: Overkill's transmission settings

Will,

I'm putting this out in the open so others might see this and find the help they need. This was posted to me over at NAIOA and intrigued me, so I wanted to talk to you about it.

Just a FYI

Hopefully ZZP is aware of the trans pressure limit that is needed for the 04 and up vehicles. Apparently the original (and current) DHP tunes contain a max trans pressure of 96 PSI and is not very good for the 04 and up vehicles (according to "Overkill"). The 1.5 BIN I received from DHP contained a max trans pressure of 96 PSI and I had to lower the trans pressures. I have the article on my laptop so I'll post some excerps when I get home tonight.

**edit**

Found it on the web again. I will only post the known pressure / slip issues and not the fixes due to the fact that they are proprietary of the creator (Overkill).

There are a few settings within the 04s that are very different than 97-03s that need to be dealt with. There are also some coding changes in DHP's coding vs stock that I think leads to an increase of the problem and needs fixing. No offence DHP!

Transmission slip: This can be caused by a few things..

1) 96 line pressure corresponds to a very aggressive force motor control setting. You can't see this table in the PT, but every 04 I've seen has very aggressive settings compared to pre-04.

2) DHP 04 computers have a greatly reduced torque abuse spark control table. This is the lookup table for torque reduction. At a certain percentage of torque reduction, it removes the corresponding degrees of timing advance as listed on this table. I don't know why this was reduced, but reduced timing removed on this table means less engine power cut means transmission slippage on some cars and obviously 04s have difficulty here.

Hard shifts:

1) referring to #1, if the transmission doesn't slip, this high value can definitely cause some firm shifting, overly firm. But the main thing is #2.

2) To combat the slippage, some people have raised the torque reduction upshift % greatly to try and cut power on shifts. I tried this too, and this really causes the firm shifting to become apparent. I don't know precisely why but obviously the PCM is trying to do drastic things to cut power output by that large percentage so the transmission can shift.

I'm assuming that the Overkill he mentions is you, so I wanted to ask...

I recently installed a ZZP PCM. I did put in there that I have an 04 Impala. But, my 1->2 shift seems sluggish most of the time, and before long on a drive all of my shifts are hard as a rock. Is this what is happening to my trans (slippage)? And is it trying to save itself by going to extreme shifts? I'll put my original PCM back in if that's the case, and I plan on sending it to you for adjustments anyway. I just want to know if my ZZP PCM is hurting my trans by causing slip.

Thanks.

Very interesting post. Thanks for sharing the info. I am running the ZZP pcm and notice the shifts are very firm and quick. I'll have to take a look at the tables when I get the chance.

The force motor control parameters do apply to all 04+ cars I've encountered, including Impala/Monte Carlos. I discovered this after a customer with an 04 CompG rebuilt his transmission at ~25,000 miles due to slippage and his new transmission started slipping immediately as well. He was running a DHP PCM. He was the first 04+ I tuned, this was about 3 years ago. This info pertains to #1 up there.

Some of the 04+ information pertains to Grand Prixs and Allures with the Series III engines and PCM controlled electronic throttle bodies, #2 specifically. The high shift torque reduction seems to cause the throttle body to shut momentarily to decrease engine power.

I can't comment specifically on ZZP PCMs in 04+s but I do know that they remove torque management, something that I don't agree with or emulate. Instead I've put a lot of research into how to rework the torque management settings so everything operates efficiently, and this in particular includes 04+ vehicles and all turbo vehicles, where eliminating torque management entirely is the "quick fix".

HTH
- Will

Sabrewings. My trans doesn't slip any more, but the 1>2 shift is very harsh. The only time it feels semi normal is the first time it shifts in the morning. The longer I drive the worse it gets.

A long time ago, I read Will's free tip about the 04 transmissions on the PT forum and applied his recommendations and they did somewhat help. Back then I was getting slipping and harsh shifting.

fwiw I had a ZZP PCM for about 15 minutes. Not sure if you saw my post about it on the Impala board or not.

I think I'm getting issues with the #1 side of it. I'll go swap it out in a few minutes and hopefully things will return to normal. Then it's off to Will.

Im having shift issues with the ZZP too. I was wondering about it because I dropped the pan and switched to Dextron VI that morning before the PCM install. Guess I'll switch back and see if things clear up. Then you'll have my PCM along with Sabre's

Chalk me up on the shift probs from ZZP PCM. Seems to down shift or upshift around 50 mph alot. Also when slowing to a turn the down shift is a little harsh some times. Yea I'm looking for another option. Maybe I can send it some where and pay someone to "look" at it *hint hint* lol

i've fried my transmission twice in the past 1 year!!! think god i bought the warrenty. only thing i can think it came from was shifting to neutral and revving???????