Sneakin' up on it a little at a time! When you're workin' with a
system that costs as much as yours, CAUTION and SMALL STEPS are
definitely good ideas to follow! Keep pluggin' Rich, and you'll get there
without needing to buy any more "expensive" parts.
Andy
Did another run yesterday. Boost hit 11.7 psi. Everything seems to be holding together OK.
Found an EXCELLENT road to let it all hang out on yesterday. Virtually the middle of nowhere and nice and straight and flat. Gentle curve in the road just a bit past where I need to be slowing down anyway to let me know when to quit pushing it. So I dropped it into fourth gear from a rolling idle and once the rpms were high enough where I didn't think it would bog, I opened it up to 100 percent until just over 6500 rpm. I didn't take it to redline because the slight curve in the road was coming up pretty darn quickly.
Boost comes on pretty strong and earlier than I had expected. I was at 105 kPa at just 1750 rpm at 69% throttle. I was only going 39 mph at that point. Acceleration was very smooth all the way to the point where I bailed off of the gas pedal.
Here's a video of that run:
The logged data I took is showing a directly linear relationship between engine speed and vehicle speed, so there wasn't any clutch or tire slippage noted. Heck, I just remembered that I neglected to take traction control off. Ah, no big deal I guess. It was a gradual increase in speed so I wouldn't expect traction control to really kick in anyway.
Car feels REALLY good lately. Throttle response is good, no errors showing up and the scans look OK to my untrained eye. Looks like car speed is pretty linear with engine rpm till I took my foot off of the accelerator pedal. Looks like a couple of rich spots in the AFR when I am in boost, though, but doesn't look too bad to me. Only thing I still have nagging me as some slight engine surging around 1200 rpm at 40 to 50 kpa while in higher gears. One of the guys on EFILive forum gave me some tips that might help out with that, so I'll make some changes to the tune and see how it does.
Did a short test run again to day just to check out some changes I made in how PE (power enrichment) kicks in and also working with idle speeds. Idle was a little bit low yesterday from earlier changes I made. I idles fine at 750 rpm but it just SOUNDS low to me. So I want to bring it up to around 850 rpm. The changes I made are doing that when the AC is engaged, but it is idling higher when the AC is off. So I want to get them as close as I can. No big deal, but heck, might as well try to figure out how to do that while I'm tinkering with this stuff.
That's the old drag strip Rich. They start where the road meets the dirt and have a line painted on the road going back towards Crawfordville. It gets busy down there on Friday and Saturday nights. Mostly a bunch of kids.
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I Have Noticed That A Lot Of People Demanding Free Stuff Are Not Wearing Work Boots.
That's the old drag strip Rich. They start where the road meets the dirt and have a line painted on the road going back towards Crawfordville. It gets busy down there on Friday and Saturday nights. Mostly a bunch of kids.
Yeah, I could see rubber on the road already there.... I probably won't go there often, just when I need to check out the tuning up in the boost levels.
That road is pretty narrow, so I hope they don't run two cars side by side there.
Well, I didn't have much headway trying to smooth out the low rpm surging. Matter of fact everything I tried just made matters worse. At one point I couldn't even keep the car running after popping the gas pedal. What I was playing with were the parameters defining the throttle body plate size and the table that converts the amount of airflow you want referenced by the number of steps the throttle plate has to open or close in order to provide that airflow. Honestly it seems that some of the options in EFILive are just rough guesses concerning what they actually do in the PCM. And the explanations are necessarily obtuse reflecting that situation. Which probably explains why the best tuners are the ones with the most experience and have done a LOT of trial and error to learn what exactly does what when changes are made.
Anyway, I rolled back to an earlier tune before the changes I made had the idle rpm a bit too low and did some driving with that. I noticed that there was a pronounced surging at low rpm when I took the transmission out of gear, and it seemed to be keeping step with what the fuel trims were commanding. So on a hunch, I disabled the long term fuel trims completely and the idle short term fuel trims and that appeared to have cleaned that up quite a bit.
The next change I am going to do is to disable short term fuel trims just in the lower rpm range where I'm having the surging in gear and see if that helps. I kind of would like to keep the fuel trims at least partially active at cruising speeds, but if the only way I can get rid of the surging is by going strictly 100% open loop, then that's what I will have to do. I think having fuel trims active to compensate for different blends of gasoline is a good idea, but I can live without it if needed to.
Actually I'm getting comfortable enough with EFILive where I am actually pulling over into a parking lot to make changes on the fly now while testing. I can even find many of the tables I need to work with pretty quickly instead of the agonizing searching that I used to go through just trying to find what I am looking for. The stuff is kind of logically laid out, but not always with the same sort of logic that I would have applied....... I've heard that HPTuners is better in that respect, but I don't have a copy any longer to look over.
Well, my "hunt and peck" style of tuning seems to be working out just fine. Nearly all of the surging is gone and the car drives pretty much like when it was stock, just with a lot more muscle under the gas pedal. Only exception is that it idles high when I push the clutch in and take it out of gear when drifting to a stoplight. Clutch in or out doesn't change the idle at that point. Idle is between 1200 and 1300 rpm during that time. Once it comes to a dead stop, idle drops down to around 1050 rpm. But the kicker is that it only does this during the first 20 or so minutes of driving. After that, the high idle goes away and it idles around 1000 rpm while drifting, then settles down to 850 rpm at a dead stop.
I can't find anything in the tuning or logs that indicates something that would change just after a period of driving like that. And I've played with every setting I could find that might cause this. The only thing that did make a change were some of the throttle follower tables, which I copied from a stock Z06 tune, and the car wanted to stall out even when just starting out. So the answer may be in there with a lot of fiddling, since there were just minor changes in those table values. Otherwise coolant temps, air intake temps, everything I've monitored doesn't change at that 20 minute changeover point. Just the idle changes for some reason. First time it happened Connie and I were driving out to the Tallahassee Car Museum and I had the initial idle running around 850 to 900 rpm. So when it went into the lower rpm period after we had been driving for a while, the car actually stalled coming to a dead stop at one point. So I had to change the tune to increase the idle overall to compensate for this problem.
Beats the heck out of me. I'm probably going to just leave it as it is, and to heck with it. Honestly it shifts better between gears with the idle staying kind of high, so it's no big deal. And it really doesn't spend that much time in that limbo period drifting to a stop, so as long as it doesn't get to irritating that "perfectionist bone" in me, then this will do.
Otherwise throttle response is great, and I even saw the gas mileage hovering between 29 and 31 mpg running at 58 mph on level roads. So I certainly can't complain about that. I might just make one more run under boost to log it and make sure that is still OK. If OK, then I will pull out the wideband and be done with it. I can live with that minor high idle thing, everything else I have been through with this car considered.
Sounds like you've got it where it needs to be! Mine does that high idle thing too when it's not at full operating temperature, idles up to 1000, then drops down to 650 or so when it comes to a stop. I'm so used to it that I didn't even think of it until you brought it up.
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I Have Noticed That A Lot Of People Demanding Free Stuff Are Not Wearing Work Boots.
Sounds like you've got it where it needs to be! Mine does that high idle thing too when it's not at full operating temperature, idles up to 1000, then drops down to 650 or so when it comes to a stop. I'm so used to it that I didn't even think of it until you brought it up.
There is a specific table in the tuning that controls that idle speed, which is what I have been playing with. It gets pretty complicated because there are separate tables for "in gear" and "park/neutral" and both for with or with the air conditioning running. Then there are further modifier tables for when the engine is considered to be under load. Idle can be controlled directly by the throttle blade position, by the air fuel ratio, and by the timing. Some of my problem might be because of the 90mm throttle body, which means that the 310 steps that the PCM can command the throttle blade will have a different value of airflow associated with each step. I think I have the correct values, but with so much of this, I'm just shooting in the dark.
When you look at all of these tables and think back what we used to have with the engines that didn't have all this computer controlled stuff, it seems like a miracle that they even ran at all.
One of these days I need to just jot down some mental notes here of things I've learned, or at least what I think I have learned.
When you're workin' with a
Keep pluggin' Rich, and you'll get there
Ah, no big deal I guess. It was a gradual increase in speed so I wouldn't expect traction control to really kick in anyway.
I probably won't go there often, just when I need to check out the tuning up in the boost levels.
Linear Mode
