Today while working on my WOT I dropped .7 sec off my 0-60 time. I had allready made a few corrections to the table previously using my but dyno. Today I drug out the Gtec and measured and tuned my way down in about 4 chips adjusting just one table ( PE - AFR Vs RPM). It seemed to run decent before, but I knew there was more in there somewhere. Tomorrow I might play with the PE timming chart and see if there are a couple more ponies hiding out somewhere.

Morral of the story. If you arent spending some time tunning it your self, you are probably down alot of horse power that you allready payed for. Dont pay some one else to guess. I guessed and got it close, and if I didn't know better I would have though it was good enough and left it alone. But I knew I would benefit by fine tunning and testing.

 

Wow!

I'd like to find about a .4 reduction in my 1/4 mile ET that way.

Out of curiosity, were you leaning out the AFR?

 

 

Yes. I leaned it out .2 at a time till the first time I didn't see a improvement, then went back to the previous AFR setting in that block. I cut .6 tunning the 4800 rpm block, and gained another .1 in the 3200 rpm block. Others reading this should keep in mind that the boundry between the 4800 and 3200 blocks is 4000 rpm and covers everything above that. Being my torque peak is at 3500, I was tunning most of my power band in the 4800 rpm block of the power enrichment AFR to RPM chart. I had the main fuel and spark charts pretty close before working on WOT.

All in all I was trying to do what Grumpy says and give the motor what it wants. Not what I thought it needed.

 

Good advice.

How did you conclude that the torque peak is 3500?

 

That is an assumption. What I did was some what replicate a ZZ4 crate motor, and am using their dyno chart as a guide to the characteristics of of this cam-motor combo. In real life the results will vary, but I bet I'm some where in the ball park. I am not going to make any HP or torque claims based on some one elses motor and dyno chart, but it did help to know what I should expect out of the combo.

My main point is that there are alot of people out there who need to tune or they never will get close to the power they payed for.

 

Yeah, I'm totally clueless on this chip burning stuff.

 

i was clueless until i started searchin for info and PMing DIY PROM genius's, so far i've managed to burn quite a few chips....with success at that.

 

Hey Z28,

How would you feel about holding a class and teaching some fellow thirdgenners the finer points of chip burning.

Bill

 

im still in the learning phase of this. im sure if you PMed Dimented24x7, JPrevost or Dewey316- just to name a few, im sure they can be of way more help than I can...

 

Out of curiosity, what were your commanded WOT AFR's? In mine, GM has a commanded WOT AFR of 12.0. I need to get some datalogging with the wideband and Datamaster to compare......

 

i had mine set to 12/1 PE AFR. on dyno the WB was 11.9/1 and 12.1/1. two runs back to back. i was shocked. i thought would be way lean or way rich(PE). i guess if underlying fuel tables decent it all falls into place. i reset to 12.5/1 andf left alone. what i still dont understand is this pe delay of 60-100 secs in stock bin. what is purpose of that much delay? that is an eternity or a 1 mile wait at 60 MPH. i understand reset to 0 secs or so but what is GM's purpose in that initial constant ? fuel economy vs power?

 

I ended up with 12.0/1 in the first three tables. 12.3 in the 3200 block. And 12.5 in the 4800 block. But like Ronny says it all depends on how close your main fuel table is. I may be off alittle in the lower blocks. It passes through them so quik its hard to tell. I tried 12.5 /1 in them but the off idle stuff felt alittle flat, so I put it back.

 

i set them all to 12.5/1 for all pe range of rpm. dont know if that was wise. maybe should be richer at lower rpms? again with pedal to metal would not AE be bringing the A/F ratios 11/1 at lower rpms till it times out and PE then would be in around 4000-5000 rpms for the duration of the blast?

 

I set it that way because it responded best off Idle. It might be that the lower part of my VE table at 100 kps is acually alittle lean and that made up for it.

 

The only case for being rich around the area of peak torque is the cat. conv. With overly rich AFRs, alot of the oxygen is starved out of the exaust and thus prevents the cat from burning off the excess fuel. With reasonable AFRs, there is still a good deal of oxygen with the unburned fuel to react and it can destroy the cat. if there is extended high loading. The super rich WOT is especially noticable with some of the newer cars. They leave trails of black smoke when in power enrich to prevent harm to the cat.

 

Try pulling some timing out in the PE Spark Adder table above your peak torque. i had alot of luck droping 4* from the 4k cell.

but as we all know each motor wants something diffrent, your going at this the right way, just start running, and find out what you motor wants.

 

I been woundering about that . First gear is gone so fast, but second and third are pulling longer and I get the fealing that a little less timing would help above 4000. I PMed Grumpy and I might do some messing with the extended spark slope.

 

The high gears will definatly bring out any flaws in your tune.

 

I'd attend! From what I've gathered with a little chip work I can wake up my stock LO3 and STILL keep my fuel economy...

Bruce (90RS305)

 

So you guys are shooting for 12.0/1 a/f ratio at WOT for the most part?

 

While it's fine to talk about commanded WOT AFRs, you really have to be careful about assuming what works for someone else is going to work for you. Kinda obvious, but sometimes that get lost in the shuffle.

In the stickies at the DIY PROM Board is an old tuning Article I did. While geared for TBI, it's true for any EFI.

Over this past weekend a few guys were over, and with an Innovative WB, and test pipe I had, within minutes we could see who was having problems, and worked on curing things.

BTW, Ken Kelly is working on something called the Speedreader that will about revolutionize TBI ecms and tuning. heavily modified source code, real time tuning, full ROM datalogging. While it sounds kinda complex, with not too much work, it is masterable. And for the price he's mentioned, it's Killer.

 

well, i don't have a wideband so i don't really know what i am shooting for

 

i have a wideband but still need a benchmark. drag strip is too far away. so i am thinking G Tech. Does it pay to spend the xtra $$ to get the deluxe version? Is that the better choice? i bring this up since i was at 12/1 on dyno (PE). i changed to 12.5/1 "commanded" in TC. i am guessing that was a good move. plugs were pulled once but not for WOT inspect. just general condition.

 

Ronney, have you been able to verify how accurate the command WOT AFR is with the WB?

I always wonder if i were to nail the VE tables with PE disabled, if i were to enable it, if the command AFR would work at all. Maybe Grumpy or Rbob can verify exactly what it is that the table is doing.

 

well that is what i did. disabled the PE and worked on 3200 and 3600 main fuel tables. seems i could poputate 2800 regularly but lack cells in those higher tables. if any other map not populated i just guessed. result on dyno WB was 12/1 just as what was commanded. so it all worked out. guess if VE in line the PE falls into place as was engineered to do. i expected who knows what on dyno. fearfull of lean. yes i have a WB but not installed cept the bung. i have some mods forthcoming and have not yet had the window of opportunity. needless to say weather here is awful for spring. rains every day.

 

was that with a cammed motor, that the command AFR actualy worked right?

maybe it is time to diable PE, and go for a LONG drive

 

yup. the first cam in sig. the bigger one going in next week(?????)
that first cam is tame.

 

that first cam is tiny.

i'm running bigger than that in my 305, and i think it is too small (i'm going bigger)

 

the plan was to run stock ECM and not tune. That changed fast when the heads were put on same time. that cam with headers and xram may have been OK not tuning. the heads changed all that. for better.

 

If your in the market for a G-tech definetly go for the delux "competion" version. The hp and torque graphs are great for zeroing in on your WOT tune. Just start really rich and take out fuel till the curves look nice and smooth and are maxed out. Don't take too much stock in the HP numbers though even with the correct weight entered they are off a good bit. I'm running high 13's with 180 hp at the wheels Just use it as an A to B comparison. Also the "competition" version is a good bit more accurate than the old style. With 4 excelerometers you don't have to level it out every time you put it in the car.

 

Hmmm... thats an interesting question. I would think that the WOT commanded AFRs should at least be pretty close to actual when PE is engaged. Granted, the VEs will probably change some when in PE vs stoich given the fact that the motor will be making more power, which will affect how it exausts and such.

 

This is definetly a DIY-PROM thread now....

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