After some suggestions, I set closed loop enable temp pretty high so I could monitor my O2 at idle in park. Now my O2 was pretty high but the P730 article put me at ease and made me realize what was going on (more radical cam...need to lower VE at low RPM's, etc).

Are there any rules of thumb for using open loop to tune certain parameters (ie idle speed) or now that I know why I was rich, should I just re-enable closed loop and start doing D'com runs and make educated changes to the VE maps?

Right now it looks like I am just going to make an stab in the dark as to where my idle should be. On a carb, I used to tune the mixture screws for the highest vacuum reading possible. Is there any similar way to use a method like this for finding a good idle set point to program?

One other question. Has anyone ever tuned their chip so it ran great in nice weather but once winter came around, it was awful? If so, what are some areas I should keep in mind to keep that from happening? I would assume IAT has a large role in that, but it isn't all there, is it?

BTW, 85 w/ a 730 conversion successfully completed! Thanks, -Matt-

 

If there is not IAT timing correction table, then you'll always be a little off in summer or winter depending on when you tuned.

VE tables are always a cut and try routine. There are jus no absolutes, unless your staying in open loop, and then a WB would be an aid. You can wind up with some really odd tables depending on how touchy you get.

Don't forget that you have AE stuff to play with, if needed

 

Thanks Grumpy. No WB here so I guess I will enable closed loop. Hopefully I will be able to get it on a Dyno w/ a WB and record some baselines shortly. -Matt-

 

BTW, I have a WB and in general don't even use it. They are a nice option, but not hardly mandatory

 

This is a interesting comment as the WB was very high cost when this was first written.

My guess is he relied on the lost art of plug reading, and listening very carefully to what his engine was telling him.

And maybe the DIY WB had not been perfected quite yet.

 

Grumpy was always known for stating that looking at numbers on a screen didn't tell the whole story and that they shouldn't be read as gospel.

I agree, and have tried to teach other people the same, sadly not too many people can tune properly, or give the engine what it really needs. They look at numbers and shoot for target AFRs, because this guy on the interweebnetz somewhere said this was the best number to shoot for.

Real tuning is a lost art form. That's why I'm glad I learn some techniques from guys that didn't have computers, infact computers weren't even a thought when the guys I know were tuning.

 

I have read and been told the same about treating the AFR as gospel, but I guess that it is a good starting point. I am trying to tune in AE and PE now, so should I just try reading the plugs at this point? Should I try to get the commanded and WB AFR close and then start changing the commanded to see how the car reacts?

Have to admit how glad I am that the car is running as good as it is in this weather. It was -5 today on the way to work and the car just screamed probably more than it ever has. How do I translate that into regular weather.

Do you guys use the IAT/CTS blending? Not sure what bins have that capability, just know that it is an option on EBL.

 

03-09-2002, 03:50 PM #1 Grumpy vbmenu_register("postmenu_557718", true);
Senior Member

Tuning Help Available Ya'll just need to do whatever it takes to get yourselves a WB.
Period.
Trying to get around it is just a waste of time.

I'd venture a guess that I've done 3-4x more chips then anyone around here, and have been tuning for going on 40 years. I have built a couple of the DIY-WBs, and now have one of Bruce Roe's LED displays.

WOW,

You can see all the AFR transistions clear as a bell. AE, MAP increases, DFCO, it's all there. Just out of the corner of your eye you can see what's going on, now.

If you don't know how to solder, it's time to learn. There is no reason not to learn something new, and if saving $400-800 isn't worth it, well your on the wrong list. No one is making a penny off of this on the USA version. It will pay for itself damn near just in gas. All the worry about injector constants bas pulse widths, all the little stuff that drives ya crazy to rough things out just is sooo much easier to see and figure out.

Ya ya, data logging, if you can't figure things out with Bruce's Display, well dunno what to tell ya.

If you haven't gotten a WB to work, you need to sit down and figure it out.

Not everything is going to be a gimme in life, some things ya gotta work at, and forgo the instant gratification stuff.


It seems that maybe something changed in his way of thinking, this is after the DIY WB was released.

 

1. As you can see from the box date, the DIY WB was already available (for several
months) by Dec of '01 when I put this one together:
http://www.corvetteforum.net/c4/doctorj/pix/wbboxc.jpg
http://www.corvetteforum.net/c4/doct...bboardc800.jpg


2. The world of Physics changed some 300 years ago, whether posters on car boards
acknowledge(d) it or not. In particular-

If you plot AFR & RPM (or VSS) vs time with a fast ADC, you have more than enough data
to evaluate fuel (or spark) vs engine power. You just need to remember that delta
power is from the exponential curve: KE = 1/2 mV*V ; and you can only measure the
transients at WOT with this method.
http://www.corvetteforum.net/c4/doct...taq24apr03.jpg

The equation comes to us from Isaac Newton, who never owned a TurboBuick in his life.
He was however pretty good with looking at numbers on a sheet of paper.

http://www.corvetteforum.net/c4/doctorj/carwb.htm has some additional discussion.

There are lots of uses for a wideband.

HTH

 

That's the key. I found a wideband a distraction. I sold it after like a month.
The only thing a wideband is good for is being able to tell people your AFR on forum posts.

-- Joe