Know what to modify, how much to add or take out and WHAT to modify in a custom chip's programming to match your car's mods ? I'm buying the necessary equipment to burn prom's next week. Only problem is... I would have no idea WHAT to change in order for my car to run better ? Diacom isn't a whole lot of help either. More timing and fuel ? More fuel ? Less timing ? LOL What do you change in there ? Any FAQs on this anywhere ? thanx

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92 Z28 L98 350
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Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

 

Some guys here think you can do it without a scan tool... Wel, you can, but it is totally seat of the pants guessing...

This is what a scan tool will tell you:

1) EXACTLY how much Fuel to add at the rpm/load (in VE tables) you are driving at (there are a lot of different "cells" you will need to fill-in, though). Therfore, you can fill-in your VE table(s) with optimized numbers, thus getting BLM as close to 128 as is possible AS SOON as possible, too.

2) EXACTLY how much spark your advance combo will take under the load/rpm you are driving at. Therefore, you can fill-in the spark table with optimized values.

3) Other extraneous parameters. like IAC vs idle speed, etc, all of which can be used to change a chip...

Got a scan-tool???

 

YES !! A Diacom Plus setup. Problem is... I really dont see how I could improve anything. I guess I need to have a better understanding of what is what. LOL

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92 Z28 L98 350
---------------
Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

 

I've given this question some serious thought and this is my answer.....

Time, Research, Experimentation, and MORE Time.

I read everything on the internet that I could get my hands on. Then I read it again. Then I researched the internet and found some more stuff ... read it, reread the old stuff, and then read the new stuff again Then I got involved in boards like this one and on mailing lists. I asked A LOT of questions and also lurked there just to read everything that everyone else was saying. Finally, I started programming some PROMs. At first I only changed the little stuff ... idle speed, fan on/off temps, TCC lockup speeds, etc. Then I went the the bigger stuff like fuel and spark using the info that I learned over that past 2-3 months. You can't just read once source of information and expect to know what you are doing ... not yet at least.

As far as Scan Tools are concerned .... I use to believe that they were necessary. In fact, I can't imagine tuning a car without one. However, Pablo has made some very interesting points that I wholeheartedly agree with. The TBI equipped vehicles have baud rates soooo slow that the Scan Tools don't give as much valuable information. AFR can be determined by and EGT guage and, if you know how to read plugs correctly you can read the plugs. My theory is that if you have an ECM with 8192 baud capability then use a Scan Tool but never ever ever rely totally on the O2 for fueling. The OEM O2 is just a guess meter ... that's it. If you have an ECM with only 160 baud capability then, IMHO, a scanner can be left out of the equation.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.587 @ 107.97mph (1.710 60ftr) on the long runner setup.
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels. Stock Wheels. No Weight Reduction.
Gunning for NA 11's with the MiniRam II and Hooker LT Headers.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

I understand why you would not think a scan tool is not becessary and I gues it really isn't. It's just that you can make EXACT fuel and spark changes if you use one instead of guesses. Yes, you may have to drive around a lot and be patient while your scan tool updates, but don't you think it's worth it for EXACT data? I do.

Yeah, a scan tool doesn't help much for WOT events and rpm situations, but to fine tune the VE (fuel) and SPARK tables, perfectly, there can be no substitute.

 

Before doing any tuning changes, one very important thing to know is how an internal combustion engine works. I've seen countless chips done my 'tuners' that were complete junk.

Traxion made some good points about doing research first. I'll add reading some books on internal combustion engines. You have to have a good understanding of how spark timing and fueling affects an engine's operation before you start making changes. Just adding (or removing) timing does not make an engine powerful. Same goes for fuel.

Nick

 

Nick is right, and when you make any changes, a scantool will give you the EXACT results of those changes on the behavior of the motor. (ie, with changed BLM and knock values)

 

Nick - GREAT. I am assuming that everyone knows how the internal combustion engine works. I didn't realize that some people here might not know that.

FastBroker - I agree. As I said ... I, TRAXION, cannot imagine burning chips without a scan tool. But, is it NECESSARY? No. Is it helpful? Heck yea! I can't imagine tuning without a scan tool. If I were forced to choose one application that gets the LEAST benefit from scan tools it would be the 160 baud ECMs. Is the scan tool still beneficial for the 160 baud ECMs? Heck yea!

But, let me make one thing perfectly clear to everyone here. Although scan tools aren't necessary, if you choose not to use a scan tool then you better have other tools at your disposal and a lot of experience at reading plugs.

Tim


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TRAXION's 1990 IROC-Z
Best Time = 12.587 @ 107.97mph (1.710 60ftr) on the long runner setup.
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels. Stock Wheels. No Weight Reduction.
Gunning for NA 11's with the MiniRam II and Hooker LT Headers.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

I agree with Tim on this . Scan tool is so very helpful. To me, I dont leave home without it I run diacom on everypass down the track.
Anyone know how to save a screen shot from diacom. I would be willing to post some of my runs. I have a latest run of 11.05 @127 with 100hp of nitrous on my 383
The diacom looked good on the run.

Dennis

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85 vette,383,miniram,ZF6,4.10's..best ET 11.81@117.00 60' 1.65
w/100HP nirous 11.05@127
http://geocities.com/bowtie8

[This message has been edited by BOWTYE8 (edited October 06, 2000).]

 

Finally I found someone who sees my point. I think that people who don't think they need a scan tool have neved use a scan tool. i cannot explain how invaluable they are if you want to be precise and concise. No games/guessing, just the facts, maam...