injectors too big?

[IsaacHayes]

There is the A body's 3100 that came with a MAF (but no MAP) that are OBDI and have a removable chip. They had a weird plenum/TB/MAF (2 of the 3 were built into as one). Other than those cars every other 3100 that was obd1."5" has nothing available for it.

[Superdave]

OMG.. what a lazy ass..

there is 1 constant to change IF your idle MAP is higher than 45Kpa (somewhere around there). Mine was so i had to up it a little. That's what lets the ECM go into the idle fuel table. He just keeps changing constants that are for the DIC or display only, that's not how you tune $A1.

I've now gone beyond $A1 and am working on getting $8D S-AUJP (modified V8 Camaro code) to run mine. It's got a better VE table and is better supported than ARUR.. but still, $A1 is pretty simple to tune for a large cam. Once i get it done (and my engine is in the car) i'll post up a V6 starter bin and all the info to run it.

I'm sure either Ben or myself could get you running in half the time.

[Alxsmt]

The older MAF sensors used on these cars did have major issues -- that's why
GM came out with the speed density update programming. However, GM later
went back to using a MAF sensor after they discovered the engines ran a lot
better with them (especially since the technology for the sensors got
better) starting in 1994.

The problem we are having here is by nature speed density systems (like what
you are using now) are very difficult to tune when you are using a lot of
aftermarket parts on an engine. This is true for any engine, 4cyl, V6 or
V8. The reason why is because the computer bases fuel and spark delivery on
the MAP sensor reading (it reads manifold vacuum) and aftermarket cams tend
to make the vacuum level less at idle vs. what it would be with a factory
cam. This tricks the computer into thinking the engine is under a load at
idle (even when it's not), therefore it dumps more fuel and pulls out timing
advance. We can go back into the programming and force the computer to keep
the idle lean and keep the spark advance where it needs to be, BUT, then
when the engine is really under a load the computer isn't going to know this
and won't give the engine the fuel and timing it needs at that point.

MAF based systems measure actual airflow going into the engine at all times
and adjust fuel/spark delivery accordingly giving the computer the ability
to self-compensate for a wide variety of operating conditions.

I wouldn't even consider having you go back to a pre-speed density update
program and having you use the factory MAF sensor that came on your Beretta
due to the issues these systems were known to have. Instead, since you are
using a newer 3400 block, I would recommend you upgrade to a newer computer.
In that case I would recommend an OBD2 system. BUT, this is going to
require a bit of rewiring work for you since the OBD2 computers use
different wiring terminals and connectors at the computer.

There is a crossover system that was used in 1994-95 applications that MIGHT
work for your application. The 94-95 Buick Century and Olds Ciera came with
a 3100 SFI MAF V6 that used a computer that looked identical to your 1227730
ECM. It used the same type connectors and wiring terminals. However this
computer is SFI which means you would have to do some rewiring (add wires
for individual injectors + cam and crank sensors). I do know the wires at
the computer connectors are in much different locations than where they are
on the 7730 so you will need to do some repinning. But nowhere near the
amount of rewiring work required for the OBD2 PCM swap. The only question I
have not been able to answer about these 94-95 computers is GM showed a
different part number for the CAM sensor used in these applications vs. what
was used on later engines and there is a question if the signal is
compatible with other sensors like what your engine has. We wouldn't know
if they were compatible or not until we try it out.

-OR- we can continue working with your current programming and see if we can
get it to come around.

Let me know what you want to do here. If this were my car, I would at least
"upgrade" to the newer 94-95 MAF computer (but would probably just go with
the OBD2 computer since there are many other advantages to doing this).

this is what he told me today. i thought you couldnt touch 94 and 95 computers

[johnnymossville]

^^^^^ HE IS THE MAN. I can vouch for his tuning knowledge, and a few other people on here can too.

[Superdave]

I won't post the username but another member got sick of their failures an came to me for a tune.

[SappySE107]

This .bin file is never going to idle. He has no clue what he is doing for OBD1 60V6 chips. I have seen it before, told him what to to, and its all the same.

http://www.grandamgt.com/forum/showthread.php?t=69916

Your answers are right there.

[Alxsmt]

i think he was trying to see if a leaner setting would help my idle on that file. WOT was 14s at 6k

which is too lean...

[Superdave]

well, it is $A1 but i don't know what he's thinking.. that BPC is way too low for 28lb injectors.

[Alxsmt]

oh. well i hope he tells me what mask he is using and sends it to me. i hate not being able to play with the little things i acually understand!! i wish he would just use the a1.bin

[Alxsmt]

i have no idea, he said i could use my $a1 code mask..

i will email him and find out

[Superdave]

well, it's not $A1.. and i have no idea why they wouldn't use the latest code...


do you know what mask they are using?

[Alxsmt]

lol i was thinking that too... and it wont let me change my idle vs temp at all with out going in limp (code 51).

the 2nd time they started tunning it i was getting files that were set up for 4bangers (rpms)

here is the latest .bin and log.. i should have a new one tomorrow. this is only the 3rd file so far since we started over... total of 18 different files since we started

[Superdave]

they're full of shit.. lol


have them send you a copy of the latest bin file they have for your car, then post it up here and we can take a look at it..

[johnnymossville]

I wouldn't think that your injectors are too big. My build is very similar except 11.5:1 cr and a #1161 grind cam (specs are below) and I'm running 32 lb. injectors. My BPC is set at 140 currently and it my need to be higher but I don't know that for sure yet as tuning is an ongoing process.

[Alxsmt]

so gmtunners.com is still working on my tune. had 2 start over 2 times... the car still wont idle when its warm and the afr is in the 10s/11s.. they are telling me my injectors my be too big to get a decent spray pattern with that little fuel..

just 28lbs injectors...

what do you guys think?