Z-type's Tune Thread

Ok well none of that did any good really. The car ran more rich than I knew it could - between -17.5 and -22.6 the entire time. So yeah that wasn't good at all. I put the injectors back to normal and put the MAF table back to normal then raised everything above 4000 HZ 1% for now.

I drove the car for a few miles and it's back to it's usual self. I'll just have to do the MAF table incrementally until it's right.

No, I never got a scan logged. That's for when I'm off again this week. I guess I'll have to stay out of the throttle for a couple days.

Z-type wrote:

As I type, another tune is being uploaded to the car. Changed the injector skew percentage from 100 to 110, and adjusted the MAF table as much as 10% from the middle to upper end. It needed it. Ill take a couple days to drive and let everything settle and see what happens!

I'd probably leave that alone or use it strictly for skewing the injectors against eachother, not correcting fueling overall. In the case of skew, the PCM knows that's happening so it cannot be used to modify AFR/fuel trims. If you need to make a big straight compensation (like for different fuel injectors, different fuel, scaling) use the injector flow rate table. Otherwise try to keep it all in the maf table if you can.

Another thing to point out is that the maf table is designed to do no more than calibrate the maf. If you find that the tune is not giving you enough fuel for your setup at wide open throttle and the maf table is already calibrated then you would want to change the Power Enrichment AFR table to actually make it richer or leaner at WOT. That table basically dictates AFR once you get into power enrichment so the number you stick in there is what it'll try to do (although there are other tables that work along with that one that changes AFR as well so it's not literally just that one number in there). If the maf is not calibrated at those open throttle ranges, then what happens is the PCM thinks it's commanding say 12.2:1 AFR but there's no way to verify itsself (because the o2 sensor doesn't work that rich) so if the maf table is perfect, you are at 12.2:1 like it wants but if the maf is off, it'll be way off.

turtleman wrote:

If you find that the tune is not giving you enough fuel for your setup at wide open throttle and the maf table is already calibrated then you would want to change the Power Enrichment AFR table to actually make it richer or leaner at WOT.

If you were still running the stock MAF, wouldn't it make more sense to just mess with the PE table? That way you could keep things simple, keep a nice MAF table that evenly increases, and eliminate variables? I don't know for sure which is why I'm asking....

On a slightly related note, what about PE Enable Vs. TPS? What's good settings for that, or leave it stock?

Quote :

If you were still running the stock MAF, wouldn't it make more sense to just mess with the PE table? That way you could keep things simple, keep a nice MAF table that evenly increases, and eliminate variables? I don't know for sure which is why I'm asking....

I would say no, because the MAF table isn't calibrated to the stock MAF sensor, it's calibrated to stock air flow. When we add boost and breathing mods, we're increasing air flow, so adjusting the MAF table makes total sense.

AA wrote:

I would say no, because the MAF table isn't calibrated to the stock MAF sensor, it's calibrated to stock air flow. When we add boost and breathing mods, we're increasing air flow, so adjusting the MAF table makes total sense.

Ah alright that makes a lot more sense now. Thanks.

matt270avian wrote:

turtleman wrote:

If you find that the tune is not giving you enough fuel for your setup at wide open throttle and the maf table is already calibrated then you would want to change the Power Enrichment AFR table to actually make it richer or leaner at WOT.

If you were still running the stock MAF, wouldn't it make more sense to just mess with the PE table? That way you could keep things simple, keep a nice MAF table that evenly increases, and eliminate variables? I don't know for sure which is why I'm asking....

On a slightly related note, what about PE Enable Vs. TPS? What's good settings for that, or leave it stock?

This is where tuning becomes an art I guess. Even with a stock maf, once you stick a smaller pulley on the blower, you're suddenly gonna be dealing with more air everywhere which changes volumetric efficiency. If the tune primarily uses a maf (not VE/speed density), then you end up playing with the maf calibration table to represent the change in VE. It sounds retarded but that's basically what's goin on.
The PE table could be critical to tune if your setup needs to be richer or leaner than stock to be ideal but that's kinda more something you'd play with on a dyno or at the track to see what gets you faster, again, after the maf is done. Personally, with all the stuff I've done to my car, my PE AFR table is stock because I'm always dealing with the maf not being straightened out. If you just can't seem to get rid of some mild KR while maf tuning, enriching PE might be something to try among many others but I don't think I'd make any big changes one way or the other without a wideband to know what the real life result is. PE enable TP can be totally left alone. You can play with it if you like. James likes to increase it sometimes to get a little more fuel economy out of it - it's all about throttle position so it depends on your build and how you drive in the first place. Generally speaking these engines can tolerate being lean longer quite well.

Thanks guys that was a good explanation. Seems so simple now lol. So, two things:

I scanned and logged on the way home with DHP...and it won't save the log. That's annoying. So I still have no information to share. In the mean time, I have a question.

If I were to do a partial write, say just the MAF table and DONT reset the fuel trims, after a few miles will I start to notice any changes I made? I didn't know if it really took days or just a few/several miles for the computer to figure out it changed.

I only ask because after that crappy tune I uploaded yesterday it almost instantly ran super rich and stayed that way the entire time.

Z-type wrote:

I scanned and logged on the way home with DHP...and it won't save the log. That's annoying. So I still have no information to share. In the mean time, I have a question.

If I were to do a partial write, say just the MAF table and DONT reset the fuel trims, after a few miles will I start to notice any changes I made? I didn't know if it really took days or just a few/several miles for the computer to figure out it changed.

For part 1, run DHP in administrator mode. Sounds crazy, but my logs don't save unless I run it as an administrator. I'm assuming you're running Win 7/8?

For part 2, any time you flash a tune that changes fueling you need to reset the fuel trims. Over time it will probably change, but it's faster and more accurate to reset them.

Im actually using XP because i have an XP machine with a serial port still haha. I havent tried to use it on W7 yet. Ill give it a shot.

And ok cool, i can do that. I can also reset trims in scanning mode correct?

Alright finally some good news on this fueling fiasco. I've been driving the car the past couple days and the fuel trims seemed to have settled out, and they're looking much better already, even with just a 1% increase (where it starts to lean out). I still can't go WOT without knock (~4 degrees, sometimes 5) but my LTFT's don't go up to 12.5 anymore. I've only seen them as high as 8.4 at the most, and they usually don't go above 6.7.

It's running richer while coasting and at light throttle, so I adjusted for that and added another 1% where it's starting to go lean again. Hopefully that gets it closer!

Also, related but unrelated - I am still going to do a Performance Shift button. I think I have all the shift pressure tables set where i want them, and raised shift points ever so slightly in performance mode tables. Got rid of 3rd gear TCC, raised 4th TCC, and raised the TCC release point for 4th gear.

I will be looking into the torque management tables once my MAF settings are squared away.

This is fun as hell!

Ahh, the memories of early tuning days. I miss it. Maybe it's time to open up the shift tables and try a new, more aggressive downshift program.

AA wrote:

Ahh, the memories of early tuning days. I miss it. Maybe it's time to open up the shift tables and try a new, more aggressive downshift program.

Ha! I'm seriously impressed at how "personalized" you can tune this tranny. One can literally program it to do ANYTHING they want. I have a good friend who's amazed by what I've done to this Riv. He just can't get over the fact that it's a Buick lol.

I honestly see no need for a Perf Shift button. As long as you aren't on the throttle constantly, you can just firm everything up at WOT. Keep everything below it to a tolerable level. The only reason I could see a Perf Shift button is if you set up a road course shift table or something....with super high shift/downshift points with no TCC. This is my opinion of course. Make it your own! Tuning is so much fun...

Yeah i know what youre saying Scott, but theres too many things I like about the factory programming to get rid of it completely. I upped the shift pressures quite a bit from stock, but aside from changing the 3rd gear TCC lockup mph to 35, it's mostly the same. i changed the performance tables quite a bit - enough to make a switch worth it for me.

So, in the next couple weeks while I get the MAF straightened out, i have a question to ponder.

What good does changing knock retard decay rate do? I have a pretty good idea of what will happen if I change the rate lower, but I wasn't sure if I should bother.

Changing the decay will allow the engine to recover more quickly in a situation where there's KR. This could be a bad thing in cases of sustained knock, because the pistons will take more abuse with each recovery.

Every degree of KR decreases power by some mystery amount.

If you are a good responsible scanner and you have identified you have false KR, I feel that is safe to increase the decay rate.

If it's true KR, it wont go away. It will keep spiking until you die.

If it's false KR it's more likely to quickly decline. Increasing the decay rate will bring your power back faster.

Use responsibly.

Got cha....no touchy.

Shouldnt need to mess with it unless you have false KR spikes and you want them to go away faster.

Thank you Charlie.

I did another MAF tune Friday night, and saw improvement with LTFT's and slight knock improvment. Never saw any LTFT make it over +6 and KR doesn't occur as easily. I watched my LTFTs and MAFF on my Aeroforce again while I was driving to and from work today (since I still can't save my scans) and made more adjustment to the MAF sensor tune. Hopefully by the end of the day tomorrow I see more improvement in my LTFT's.

The only real time I have knock is in higher boost 3rd gear applications, or sudden high-throttle downshifts. The downshift knock is just a blip and will go away in a second or two, but the 3rd gear high-load/boost knock is steady and constant until I let off the throttle. I hate MAKING it knock but I have to know the limits.

Plug +6 into the spreadsheet at the MAFF value you're seeing it. Reprogram and reflash...

Just to clarify again, +6 in the actual frequency cells?

First, make sure you have the "Current MAF" (green column) set to match your existing MAF table values.

In the sheet, under "Scanned LTFT (%)", where it says "Enter values below..."

Find the row with the MAFF value where you saw +6 and enter "6" in column 1.

Your new MAF value will be in the yellow highlighted column.

Ok that's what I thought. Thanks!

Doing the change with the MAF table didn't really do much unfortunately, so I put the tune back to how it was, and readjusted twice more in a couple days. It's much better now in general. LTFT's not going over +3 now.

I know I could probably get a little more aggressive but I'm just taking the adjustments one step at a time. It's getting much better, almost exponentially, every time I tune it. Most times I'm on throttle, LTFT's are at 0, heavy it gets up to 3 as I stated. Light throttle and coasting it's usually -1 or -4ish. Not horrible, if my knowledge is serving me!

If not MAF table, what did you readjust to get LTFT closer to zero?

Im sorry i should have clarified. I did change the MAF like you suggested with your chart, but it made it way too rich.