I am working on my 87 GTA and here are the list of mods:
350 bored .60 over, forged pistions (10.77:1) Dart II heads 200 cc intake runners, LT1 intake, comp cam .510 lift and 220int and 230 exh duration, I think 114 lobe seperation angle, 1.6 roller rockers, hooker long tube headers and a 2700 rpm act converter. I have the 89 maf and the arap as a base bin file.

The problem is when it is idleing the blm's slowly climb to 140-150ish but any slight movement to the throttle it goes to 128. then when I am going down the road 35 mph or so and the scan tool says tps voltage .84 the blms are at 108. I have burned several chips and have not fixed this problem. I iniatialy have messed with the maf table 1 and had the injector lbs per hour set at 26. And it had very good power from 3000 rpm and above. Today i changed the maf tables back to stock arap and changed the lbs per hour to 28. I then had a very lean condition (160). I have got it as close 128ish as I can get. I then took it out for a drive and it has lost alot of power. Although I have about 30 knock counts and durning a wot run I see no degrees of knock retard. And also when it shifts into second it now falls on its face till the rpms get up. Any ideas on to what tables I now need to modify, or where i need to pay close attenion to. I am much a newbie and have alot to learn. I have spent many hours searching the archives and have not really found an answer that I understand.

 

Use injector constants to get your driving ranges close to 128.
After you have gotten them pretty close use MAF table 1
and 1 only to get your idle richer.
Look at what your Grams a second are when you are lean and
raise that part of the table by the % you are from 128.

 

I seem to have a similar problem. Except when I give it gas it goes almost full rich and when I am cruising the O2 mV drops and stays at double digits. Could the lean at cruise be cause by a manual transmission? Figure the momentum alone will spin the motor while the computer is trying to let it idle.

I was originally trying to use the MAF table but was told that it would cause other problems. So I tried to use the injector vs. battery voltage to richen things up at idle. I still have my fuel pressure pretty high to keep from going to lean. My fine BLMs went up to 182 at idle once!!

So whats the story, can I adjust the MAF table without really messing up things or not?

 

Many will argue the point,But i can tell you it solved my idle problems and no other problem arised except for
better drivabiliy and great response.
Alot of guys lately have been looking into the code and talking with GM's old engineers and have been told small changes to MAF tables will have no negative effect. I believe them..

 

Right now when the car idles it is right at 126-130ish. I call that tuned. Now when I am crusing it instantly goes to 108 when I touch the gas. Which table do I look at now??

 

Unless im missunderstanding you,under normal light cruise you are rich - correct?
If that is the case raise your injector constants till you get the normal driving range close,upon doing this your idle will go lean
when that happens i suggest you use MAF table 1 to make idle
back to 128..

 

I basicaly had this the last time and the idle surged. I will try it again and see what happens.

 

Well I'll give it another shot and hope for the best... I was making a litlle headway with the MAAF table so it wasn't all that bad.

 

Make small moves ,and only at the grams per second that you are having trouble at.

 

Also before you make any MAF table moves make sure your idle air counts are between 5 - 30 at warmed idle.
That should be the first thing you check for idle.
If idle air counts are 30 plus shut off car open idle screw 1/2 turn
then restart and check again. opposite for idle 5 and under.

 

Alternatively, you could increase your injector size to get the overall BLMs while cruising in part throttle up to 128 and then use the Injector Pulse Width Correction vs Battery Voltage to get the idle back to 128.

I think this would be a lot faster with a lot less playing with those MAF Scalar Tables. I would avoid touching those when you don't have too. And in your case, there is a way of getting you much closer to 128/128 without playing with the MAF Scalar Tables.

 

Well my MAF is ported, so it is further off than it should be. I also tried the injector scalar vs. battery voltage but it did not seem to do anything. How much adjusting does it take to see a difference from that table?

 

Well you will change it in %,
(also check the gram ps and BLM in park and neutral) .
Say your idle BLM in park/neutral is 150 @ 9.1 grams per second.
150 is 17% higher than 128 there for in MAf table 1 change
that value (9.1) x 1.17 = 10.6
If you want to mail me a bin and tell me your GPS @ idle (park and
drive) and blm value in park and drive i will make change for you
and you can see what i did.

 

I was actually making some head way with the MAF tables so I will concentrate on them some more. It was the injector scalar vs battery votage that didn't do much for me. But just to make sure I'm doing it right I would find the closest value to my idle and make the GPS higher by a certain percentage. If it falls between 2 values I will have to change both of them by the same %, correct?

Thanks for the help.

 

You got it.
You may just want to go 1/2 the percentage to start
but it wont hurt either way ,Let me know how it goes.