Aaron91RS

Here are my newbie questions for tonight. Ok I have two fuel tables I can edit. main fuel table #1 %VE has variables of Map,RPM,%. But the table only goes up 3200RPM's and the other main fuel table #2 %VE adder has variables of RPM,%. It goes up to 6200RPM's. So is the second add or subtract the amount of fuel at a given RPM I tell it no matter the MAP reading? Now the first table is much more complicated. Map value across the top ranges from 10,20,30...100. with RPM's down the side. Now at 400RPM's(idle) what is the standard Map reading? 10,20..? Now if it for example is 10 at 400RPM's how would it ever be 60 at 400RPM's. Then if you step on it does MAP go toward 100 as RPM's go up? This is just a guess. If so though wouldn't values read be along a diagnol line all the time? When would you use the other values. Anyway this is just a guess. Right now my goal is just to get a ruff chip to lean fuel from 0-2000RPM's a lot, and lean a bit from 2000+ Thanks [This message has been edited by Aaron91RS (edited July 12, 2001).]

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Grumpy

What ecm are you using?.
Too many folks around swap things out and leave that detail to be assumed. I'd perfer to know what ecm your using, and something about what engine mods you have.

Aaron91RS

I am using the stock ecm.
Mods are a complete 383 engine that would take to long to list.
But diacom tells me I am running rich. So I want to understand how to change fuel tables.

Brent

Are we to assume this is a 91 RS? Some people have cars different than their username. The Intro article covers fueling and so do some P730 articles.

If you don't mind I'd like to see your Diacom captures.

wildkat@paonline.com

89vette

sounds to me your looking at a VE table and the PE vs RPM table. If your using $8D, then the first VE table should be from 400 to 1600 and the second from 1600 to 5600. What software are you using?

Jason

leirch

Sounds as if your using the TBI computer still? The #1 VE on the 8D goes from 400rpm-1600rpm in 100rpm increments and the #2 VE goes from 1600+ in 400rpm increments.

Like mentioned, MUCH more info about the car and computer is needed.

To answer the question, MAP is basically LOAD on the engine. Whenever you give it gas it usually puts more load on the engine until the engine "catches" up with itself and then the load levels off or holds at a given position, the key is to get it held at a steady position with a given load that way you can get accurate numbers. Load at idle tends to be higher than when cruising down the road also.
I know I can get MUCH higher load at the lower rpms if I leave the car in 4th gear(manual tranny) and then go about 20mph. That puts ALOT of load due to the lower gear and the engine trying to compensate.


Brendan

------------------
1987 IROC-Z L98,SR,EB 6085's,LPE 219/219 SR Cam, Crane 1.6RR, EB TPI Base, 58mm TB, Stock T5 Tranny(SUCKS), ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, Aluminum DS, 94 Disk Rear, Adjustable Prop Valve, Precision 3.73 Gears, Weld in Sub-Frame Connectors, Hotchkis LCA's, KYB Shocks/Struts, Poly Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm, Big stereo, 730SD Conversion.

To see the ROC, Check out the webpage Here

Aaron91RS

Yes it's still a 91RS with the stock 8746 computer.

With the tables the RPM's go from 400-3200 on the 1st and 0-6400 on the second so I have a lot of overlap. So I don't know which table to edit.
The program says gm8746.exe. so I guess it's just for this one computer.

Brent

Edit the Main Fuel #1 for 3200rpms and anything under that.

Looking at your diacom log, it looks like the idle is quite rich.

Since you car is idling a 1000rpms and 35-40KPA you want to find those cells and change them accordingly.

BTW: changing the Diacom to Metric will give you a KPA MAP reading instead of Inches of HG.

[This message has been edited by Brent (edited July 14, 2001).]

HighHopes85

Long story short-find out why you are rich first. It is probably because your engine is less efficient at lower RPM's but is more efficient at higher RPM's then the original engine. If this is the case, then start tuning...but just make sure it isn't a problem with fuel pressure or something similar. -Matt-

leirch

A 383 idling at 35-40kpa isn't very good is it? Well I guess it depends on the idle.
My car idles at 55-60kpa. I guess it all depends on the cam huh?

Brendan

------------------
1987 IROC-Z L98,SR,EB 6085's,LPE 219/219 SR Cam, Crane 1.6RR, EB TPI Base, 58mm TB, Stock T5, ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, Aluminum DS, 94 Disk Rear, Adjustable Prop Valve, Precision 3.73 Gears, Weld in Sub-Frame Connectors, Hotchkis LCA's, KYB Shocks/Struts, Poly Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm, Big stereo, 730SD Conversion.

To see the ROC, Check out the webpage Here

Grim Reaper

Brendan, the 35-40 kpa can occur because of a couple of things: 1) he has a very high vacuum (the lower the Kpa, the higher the vacuum) or 2) the car is at a high elevation.

I note the latter, because I know that at high mountain passes, my kpa at idle drops significantly.

It might also be a combination of both.

leirch

Glenn,
That makes much more sense. I never even thought about that. So basically, I could drive a thousand miles and get some good tuning in huh?

Ok well that would be a little anal, I don't think I'll be doing that.

Brendan