Night run.....Cobalt SS/SC vs 3rd gen Eclipse GT

It was a nice quite cold night, I was bored so I decided to run some logs for the cold air and tweaking the tune a little. I Drive into town and make a few WOT runs along the way. I park at the post office, check my mail and tweak the tune. I was running a bit lean on the top end so I adjusted accordingly and flashed the computer. Now to drive home and see my results.

I roll past the Wally world I see a nice couple in their 3rd gen eclipse as I pass the intersection and he's eyeing my car as I drive by. He quickly makes a right hand turn and follows me out to the hiway. Once again I'm at the last light leading out of town and he's got to be inches from my rear bumper. I give a little more gas than needed and inch forward while I wait for the light. He does the same.

I pull out normal and clear the car next to me, he whips over to the left and pulls up next to me, I look over and I don't hear an exhaust, no blow off, nothing so I figure he's gotta be stock, poor guy doesn't know what he's getting into. The computer screen is lighting up the inside of the cabin and I guess he sees me laugh a little after I look over at his car. I hear acceleration but no down shift, I laugh a little more cause he's gotta be auto. Oh well I need to make a few WOT runs to test my tune anyway so I follow. As we clear the last car we have a nice open road and were coming on the straight where I do my WOT runs anyway.

According to the logs we were doing about 90 the first run. I paced him for a bit then he floors it, I down shift and pass with ease. I pull a few cars tap my breaks and slow to 80. I wait to see what his reaction will be. He comes up quick and I thought he was gonna do the ricer flyby when he slows to pace me, I wait for him to floor it again and we get the same result. I tapped my breaks again slowed back to 80. This time he just kept on going. I got my WOT logs and decided not to persue. When he got to his exit I waved as I passed. Checking the logs my AFRs were a nice straight line during those runs. Not a bad MAF calibration if ya ask me......

Umm? Nice Races?:dunno:

I'm assuming you're using HPTuners for all that, have you ever had to adjust Long Term Fuel Trims under the Main VE table?

I haven't tried that yet. It would be simple enough while in closed loop, you could just copy and paste by % the LTFT and smooth the cells that were not hit. The problem for me comes when I go into open loop the LTFT are all zeros. You have to rely on your wideband. Since I don't have the pro version of HPT and I don't have a histogram to monitor % AFR difference.

There is a method where you can splice into another sensor and send the output that way but I'm still leary about splicing wires from another sensor. You can then set up a histogram to get the % difference.

I've read adjusting the VE table along with the maf will get you a better transition to WOT, so some day I will be doing the VE table..

Shame on you, picking on an auto DSM. So, do you know if it was an N/A, GS-T, or a GSX?

Being that it is a 3rd gen not a GST or GSX.

Most likely not. I would assume that he would know by the laptop what he was getting in to, as I have raced twice with HP tuners going and both times the kids were pretty weary of the laptop :)

I havent had any time to do any logs of any kind lately. Im just saving up for the wideband so I dont blow shit up!

Nice run man. I raced my buddy's GT back when I was stock and put a healthy amount of cars on him, I posted the video last spring on here I think.

Being that it is a 3rd gen not a GST or GSX.

http://i228.photobucket.com/albums/ee262/m0skaudancer/TacticalFacepalm.jpg

I'm surprised you didn't razz me a little for that.

^^ nice! I totally didnt remember that 3rd gens werent turbo...

Yeah, stock we put 7 or so cars on these guys, so with your mods it probably would get ugly in a hurry.

nice...

http://i228.photobucket.com/albums/ee262/m0skaudancer/TacticalFacepalm.jpg

I'm surprised you didn't razz me a little for that.

Haha, I'm just to nice of a guy. :D

Haha, I'm just to nice of a guy. :D


Since when? :eek7:


:biggrin:

jeez you call yourself a moderator of a car forum??

:icon16:

Mods of car forums are notorious for being...well...

One thing I'm curious about tuning with HPTuners, how do you guys adjust your A/F ratio in order to get the car just right? I have to use an FMU on my truck because I don't have much of a choice (they don't make bigger fuel injectors for my style of fuel system), so I don't get involved in the A/F ratio part of HPTuners.

I think its all in the timing aspect of the car, though dont quote me on that.

I think its all in the timing aspect of the car, though dont quote me on that.


Timing and AFR's are two completely different things.

Devil, I don't have a wideband yet so I haven't messed with my AFRs yet. I think you may have to tune by calibrating the MAF, but I'm not too sure.

Meh i thought timing influenced the AFRs in some way. I know nothing of tuning.

All I did was make a "penis" gauge on the dashboard :D

Timing, or Spark Advance as its sometimes called, won't effect your A/F ratio. Ultimately you want as much Advanced timing as you can possibly use without the engine knocking (You can tell that by the Knock Retard sensor being anything other than the value 0). More timing, more power. Air and Fuel is only affected by just that, how much air goes through the intake, and how much fuel must be added to keep the ratio 14.7 cruising or roughly 12.5 WOT.

I noticed that there is this table in HP Tuners called Power Enrichment, and by looking at the description gave me the impression that this is the only real thing you need to adjust for your A/F ratio, but I'm not 100% sure. Hence why I'm curious. When you guys put bigger injectors on your vehicles for larger amounts of boost, are the injectors usually bigger than whats necessary? In other words, can you safely go WOT and hit full boost and not have to worry about it going lean?

Here is that PE table and the description. If thats all you gotta do for A/F tuning, then it looks pretty simple.
http://img380.imageshack.us/my.php?image=powerenrichmentpz2.png

The 42#ers are almost maxed on the 2.9 pulley on a GM stage 2 tune, hence why we get knock retard at around 6k in Torched's car. My tune is different, and I have yet to get a problem with that.

Maxed what? Maxed out fuel pressure?

Intector Duty Cycle, or IDCs.

What percentage is he at?

We havent logged since the car has been running, so we dont know yet. But I may be getting KR because I'm running rich up top with the GM tune. I dont think im leaning out even though I may be running up to 95% IDC. I may be getting 60# injectors soon so I have alittle more cusion....and then I can drop a pulley size after some cooling mods:evillol:

Screw droppin pulley size, I will just throw the GT30 on there :D

Still got a question or two about your experiences with HPTuners, as there is so much to the program that I'm not really using at this point but interested in understanding better. I think you all mentioned somewhere that you were doing "MAF Tuning", what table(s) are you adjusting with the Mass Air Sensor in HPTuners? What is that doing for you as well? Are you basically making adjustments to your A/F ratio through that?

We havent logged since the car has been running, so we dont know yet. But I may be getting KR because I'm running rich up top with the GM tune. I dont think im leaning out even though I may be running up to 95% IDC. I may be getting 60# injectors soon so I have alittle more cusion....and then I can drop a pulley size after some cooling mods:evillol:

Holy crap, 95%. Those things are running pretty hot. The highest I'd go before getting bigger injectors is 85%, that's me though. So, how's the idle with the 60# injectors, still decent? I'm used to CC ratings and I'm too lazy to convert.

Poly, I'm still not used to this lb/hr thing lol. Our 42.5 lb/hr injectors are close to 450cc. The 60's are close to 650cc. Some tunes seem to idle allright, but the ones we have for a buddy's car don't idle too great.

Still got a question or two about your experiences with HPTuners, as there is so much to the program that I'm not really using at this point but interested in understanding better. I think you all mentioned somewhere that you were doing "MAF Tuning", what table(s) are you adjusting with the Mass Air Sensor in HPTuners? What is that doing for you as well? Are you basically making adjustments to your A/F ratio through that?

I don't have my computer with HPT so bear with me here.

Under the Airflow tab there is a table for the MAF Sensor, its a one line table and increments up by frequency. I'm not sure if your truck would have that or not. Sounds like you do your adjustments with the VE table and the MAP sensor. With out a wideband to determine the difference between the commanded AFR in the PE table and the actual reading on the wideband it'll be hard to calculate the difference and adjust accordingly.

Quick and dirty explination of the MAF table. The MAF sensor uses frequency to determine airflow. The numbers in the MAF table represent that air flow at that frequency. Make these numbers higher and the computer thinks more air is coming in and will adjust the injectors accordingly or add more fuel. Lower the number and less fuel will be added.

The wideband is your source to determine the Air Fuel Ratio. The MAF is the Air and the injectors are the Fuel. The computer takes the reading from the MAF sensor and adjusts the injectors duty cycle to the commanded AFR.

So if my commanded PE is 11.7 AFR, or 1.3 on the PE table, during WOT and my wideband reads an AFR of 12.3. That means my MAF sensor is reading low and I have to increase the value of the effected areas on the MAF table by 5.3%. If you don't have a MAF sensor to adjust you will adjust the affected areas on the VE table by 5.3%.

My duty cycle is running about 90% by redline. If I lean out my commanded afr to about 12.3 my duty cycle drops to about 87%. but then I get knock and have to adjust the timing which will affect the AFR slightly, not sure why though but it does.

Don't know if that explained anything but PM me if you have any questions and I'll try to help....

Thats very interesting, and it sounds like a better way to tune than the VE table. From what I've always heard is that the MAF has been a superior way for computers to read the air going into the engine rather than just have the car use a lookup table to assume whats going into the engine.

The computer in the '01 and beyond Chevy S-10 uses the LS1-style computer, so I have all of the stuff you have. I can do MAF tuning, VE, PE, torque management, all that good stuff. The problem I run into however, is the fact that GM decided to continue using an archaic fuel injection system with their 4.3L V6. Its like a mixed breed of a throttle body style injection system and multiport, and no one makes bigger injectiors for this setup. However, there is a conversion I can do by buying the intake and fuel rail setup they use with the 4.3L V6 in boats, and one day if I decide to do it, knowledge of this kind of tuning will come in real handy. Its crazy how powerful this HPTuners tool is, so much you can do with it.

I hear ya, there are so many tables to manipulate. Now I need some dyno time to learn more