Z-type's Tune Thread

Heeeey everyone!

I figured that even though it's early in the process, I'd start my tuning thread! I'm extremely new at this (just started today, in fact) and I know I'm really going to be relying on the input and advice from everyone.

Some background:
I got a DHP software and hardware package from a member here on the board several months ago and just hooked it up to my computer today. As most with DHP, I had to fuss with the setup for a little bit before it would communicate with my PCM. I was able to read my PCM and 'download' it onto my laptop, take the laptop away and edit it a bit and explore the tables and the program.

So far, I have changed the fan settings to come on earlier with my 180 degree thermostat, and raised my idle to 700 in gear (because solid front mount - touching the gas a little to get it to 700 on my own seemed to help, I figured adding it to the tune couldn't hurt) .

I suppose my main goals are really to make the transmission do what I want it to do. It's a mostly mushy Buick transmission. I do have a modified ZZP shift kit in it and it's quite nice but I know it can be better. I have studied Aaron's and Scott's shift pressure and shift time tables so i think I know what I want to do there. I also want to get rid of TC lockup in 3rd gear altogether.

Just from reading and poking around in the tables all of this sounds pretty harmless and mostly easy.


So now just a question so I make sure I get EVERYTHING RIGHT. For those of you who still use DHP, like I said before I 'downloaded' my PCM and edited a few things, but I'm just curious if all I REALLY have to do is write that file I edited back to the PCM? I know there's a few Write settings to pay attention to and/or adjust, but if my thinking is correct, a Full Write is probably the best option?

Since I'm using my stock downloaded file, just edited, I can't forsee any problems in particular, but I wanted to know everyone's thoughts.

Thank you everyone!

Awesome. This is exciting stuff.

Without spoiling things too much, I'll say that tuning the shift settings was one of my favorite mods, and it will likely change your perception of this car altogether. I tossed out my INTENSE "med" shift kit and never looked back. Tuning just makes it unnecessary.

I'd do a full write the first time, just to make sure everything gets a nice burn into the PCM. From there I've always done partial writes, unless I'm editing more than one area of the program. Example, if just making MAF (fueling) curve adjustments, a partial. If changing shift points, fueling, and timing all with one flash, do a full.

People say to do a CASE learn from time to time. I've never done one - even after removing the entire engine.

Can't wait to see your tuning results!

Another good thing to start with besides messing with the trans tables and removing the governor is to import the timing tables from an 04+ Grand Prix. They're a bit more aggressive so you should see a better throttle response and higher highway MPGs (I get ~30 more miles on a tank now). Obviously do some scans to make sure your AFRs are good and you're not knocking.

I agree on the trans tune. It can/will change the whole car IMO. Tuning the trans is probably by far the most "felt" tune compared to anything else. You're gonna have a lot of fun with it.

ALWAYS keep a stock tune on hand. Every time you make a change, make sure there's a copy of the previous tune to revert to. I got lost in tuning land once, and I'll never do it again. I'm fortunate due to my job though. I ended up having to flash my PCM via GM programming, and then downloaded that file to DHP. That bone stock file will always stay saved and NEVER tweaked.

Wow thank you for all the advice, guys!

Aaron - I thought doing a full burn might be better. I will likely be doing a few tables at a time at least, and it doesn't look like writing to the PCM will take very long. Maybe 5 minutes tops. No big deal. I'm just so paranoid about 'bricking' the car lol.

Matt - I had read that somewhere, about the 04 GP timing. That would be the GTP's I assume? I'm not sure I saw where to edit the timing tables...I'll have to do more poking around.

Scott - Funny you mention keeping a stock file around. The first thing I did when I saved my PCM's downloaded file was copy it to a different name so I could edit it lol. My dad and wife work in IT and they're always beating it into my head to save everything all the time, which I'm pretty good about doing. So yes I'd really like not to cross any wires, so to speak and upload a tune which would cause actual mechanical problems. Or any problems.


In general I think I have a pretty good understanding where I need to go and what to do with transmission tuning. I really think I'd like to rig up a Performance Shift button, like Turtle did. I think I would improve upon the 'normal' tune and performance shift tune would be mostly TCC setting changes and slightly more line pressure, etc.

I wonder if the traction control button can be a trigger for the performance shift wire to the PCM?


I guess the next biggest thing I have to learn is fueling and getting my LTFT's closer to 0.0 more constantly. I haven't even LOOKED at those tables, nor do I have any idea where to go first. I really haven't had to learn this much since college lol.

I would like to see a nice scan/spreadsheet with some WOT of just how your Riv is now with no tuning.

Then let the games begin!

Looking at scans is like looking at:


It may look like a bunch of jibba jabba backwards japanese, rows, and columns, but I see a car in action.

Well I can tell you already the car has at least no knock under normal conditions. Sometimes, MAYBE uphill at WOT when it's completely heatsoaked I get 2-3 degrees, and I would expect anyone to get that.

LTFT's during WOT are anywhere between +6 - +10 and O2 is about 890-920. That's just from watching my Aeroforce constantly.

Once I learn how to properly scan and log (I've heard DHP is not a great scanner/logger) then I will certainly share. I really value the opinions and advice of the more experienced!

Z-type wrote:

Matt - I had read that somewhere, about the 04 GP timing. That would be the GTP's I assume? I'm not sure I saw where to edit the timing tables...I'll have to do more poking around.

Yep. To edit the tables go to Calibration Data - Fuel - Spark - Base Timing. Then just import the BFS, GFS, MBTS and ATS tables from this bin: https://www.dropbox.com/s/2l3leg442tektjn/2005%20Grand%20Prix%20L67%20-%20CompG%20Stock%20-%2012596629.clg?dl=0

To import you can either export the tables off the GTP bin, then Right Click - Import - From File, or you could open both bins then drag and drop the new tables.

Z-type wrote:

I wonder if the traction control button can be a trigger for the performance shift wire to the PCM?

Yes but it would require you to have a latching relay. What that would do is let you press and release the button and the relay would latch and keep the perfshift circuit active after you let go of the button. So it would behave just like when you press it to turn off traction control. I can point you to the relay I have used for that myself. The only issue I can foresee is that if the latching mechanism in the relay glitches once (it's a mechanical device after all) then the traction control state and perfshift state will be reversed with no way to readily correct it again.

What you're describing is called a soft latch switch. It can be done with a relay like described, or you can build a digital circuit without the mechanical "click". I can help if you want you build one, or I can build one for you. I do happen to have the supplies on hand.

AA wrote:

What you're describing is called a soft latch switch. It can be done with a relay like described, or you can build a digital circuit without the mechanical "click". I can help if you want you build one, or I can build one for you. I do happen to have the supplies on hand.

Yes. I haven't found that to be 100% reliable either though

The Arduino micro-controller hasn't let me down yet.

Oh I didn't even know you were suggesting a micro controller. I thought you were talking about something tuned with resistors and capacitors and stuff

It's a little more than I like to spend, but look around and you can find the mini boards cheap.

Matt - thank you that's very helpful! I think that will be the next round of tuning after I get my transmission where I like it. Saved!

Thank you Aaron and Codith! The TC button idea is neat but I don't know if I want to get THAT involved. No, it's not a lot of work, but I think I could just remove my CD holders in the center console and make some sort of button area. Just need to find a cool switch .

Codith, in the thread from a couple years ago that said you need to change two lines of 'code'? Then just have a switch to ground in that one PCM connecter pin? Seems simple enough. I really think I want to do that.

Well like I said before, I'm probably going to write my first tune here Tuesday or so. I have a car to detail in the morning but after that, it's fun time.

Not trying to sway you, but you can have Perfshift active all the time without a switch. Tune softer stock-ish shift values for the lower throttle/RPM operation, Perfshift-ish values for heavy throttle. Perfshift is all relative - the real decision you're making is to have a button or not.

It's kinda like a timing control. You could make a switch that gives you a hotter timing table when you want, or you can just program the hotter timing where it's needed and let the PCM do the work (as it's done from factory).

You know what, I knew that lol. That makes a lot more sense to do. That is how your program is set up correct? I may or may not go as aggressive as yours (I know it's not crazy).

I don't have my laptop with DHP around right now, is the 3rd gear TC lockup something that can be switched, with a button as I suggested? I cant remember what I saw...

What I'm getting at is keeping most of the pressures and shift times the same as yours for example, and being able to switch to perhaps a slightly different set of shfit settings AND adjusting the TC lockup settings. I'd like to keep 3rd gear lockup and 4th gear lockup where it is, but not all the time.

My perfshift tune is set up that way. It's not that aggressive at all - fast firm is good for clutches, but I'm not chirping tires or anything. Buttons can be fun, though. If I had a good place to mount one, I might try it.

I don't think TCC lock-up can be disabled with a button, but you can disable it in normal operation, then use cruise control to activate it (cruise TCC can't be disabled). That's what I did when I still had TCC lock-up.

I'd just disable TCC lock-up in third. There's really no point in having it. 4th gear is much more usable without TCC lock-up as well, imo, but fuel economy will suffer. Don't disable 4th gear TCC unless you have a good trans cooler.

Thank you for the explaination...yeah im definitely keeping 4th lockup, maybe not until 45 mph like my T-type.

Cruise control operation - do you mean just turning to switch on or having the actual cruise control in operation and cruising? Sorry for so many questions. Im just trying to clarify what i can REALLY do and not do.

I mean activated cruise control, as in engaged cruise. When you do this, your TCC lock-up values from the cruise table will be active, even if your "Normal" TCC lock-up is deactivated. I know, it would be cool to use the cruise on/off switch for TCC, but I don't think it works like that.

Haha ok....that's what i thought. Thanks!

The two lines of code I mentioned are two parameters you can change in DHP - perfshift enable and trigger debounce time or some such thing like that. You just change that perfshift enable to a "1" instead of a "0" and I'll have to check whether I changed debounce or not. PRJ Paul was the one who originally did that for me I think.

AA and I have been going at it for a while about the real usefulness of the perfshift feature but I say definitely do it. It's practically a free mod. What I like most about perfshift is I can make extreme changes and not really have to worry about if it's gonna be a problem some of the time. The main thing about it, though, is that you can tune the trans to do anything but you cannot tune it to anticipate your inputs (throttle, etc.) in advance. I have my perfshift settings hold lower gears even with basically no throttle and it's really nice and sharp about zipping around and manuvering. Sometimes I'm driving and want that, other times not. Perfshift gives you two personalities at your fingertips. I actually find that I use both states about 50/50. I've actually made the normal mode a little more lazy than stock. Upshifts are about the same but I've made downshifts slower to keep the car in the higher gears longer and I like it - less upshift-downshift-upshift-downshift when your just creeping in traffic or something.

That makes perfect sense to me - two different personalities. It's nice to have the choice but I'm just not sure what I want to do yet lol. I think I'm at least going to try Aaron's program first to see how it treats me in every day driving for a week or so, and if I feel I need to switch it up, it's easy enough to install a switch. Thank you!

I like how most of this thread so far hasn't been much about tuning - it's whether or not i want a stupid button lol. Either way, I'm really starting to understand a lot of this and I'm really excited to learn about this kind of thing. I like figuring out the workings of it all and seeing cause/effect. And it's not just sitting at a computer...it's getting out and doing things too.

The good thing about tuning, you can try one program while you're writing the next, then compare.

I see where Codith is coming from. With perfshift engaged using a switch, it will stay in the lower gears more, even when you're off the throttle. That can be a lot of fun. When I want that kind of performance, I grab the shifter and usually head for 2nd gear lock-out.

I'm in the middle of programming right now, actually. I kept 3rd gear TC lockup but adjusted it to a higher MPH, and same with 4th gear TC lockup. I changed all my shift times to at least .175 seconds (that's what my Aeroforce reports where I like it).

I'm not going to change shift pressures just yet, as my shift kit that's installed actually does a great job already at firmness, even at WOT, so I'm going to experiment to see what adjusting the shift times does first. If I don't like it, I'll change to the stock Performance tables, and then if I don't like that, I'm going to try your tables Aaron.

Finally, a goal! lol...