Tuning a 93 3.4 Firebird

[tkoforpresident]

that one flew over my head obviously...

i'm saying normally, the kill value is say 108 and restore is 105. my theory is that if kill is still 108 but restore is above it, like 111, the PCM would still limit speed to 108, but it won't suffer the massive bog down to 105 before the fuel kicks back in.

basically, instead of waiting for the speed to drop, it will maintain it at exactly 108 by alternating between cycles where fuel is injected to speed up and fuel is held to slow it down. a much softer way to limit speed.

ah, now i see what you mean. So instead of hitting a brick wall, it's more like a soft pile of marshmellows????


i think you should test the theory out, since i won't be going over 100 any time soon lol

[robertisaar]

i might have to.... although i'll set it at 61 and have the wife tell me how well it works out

yes, marshmallows, not bricks...

[ForcedFirebird]

[tkoforpresident]

awesome John!

so the 4 smaller connectors are going to plug into the 7727 pcm, and my original 3 harness connectors will plug into the other two ports?

[robertisaar]

AHH, it's a log manifold!

[ForcedFirebird]

AHH, it's a log manifold!

Twin turbo!

It's a prototype

[robertisaar]

Twin turbo!

It's a prototype

you don't have to tell me twice, my almost-tarantula harness is sitting happily under the hood of the MC now...

[tkoforpresident]

answer my Q??

[ForcedFirebird]

answer my Q??

You had it right. 4 connectors go to the 7727. The grey one should be green, but since you don't have A/C, I was able to use up one of the other's I had.

Anybody know what ECM the black connector comes from? The 7727 should be orange, white, green, blue - but I have seen them orange, white, gray, blue and black, white, gray, blue.

Some of the pins are missing and/or open so they don't match exactly.

[robertisaar]

here is some info for ya john.

all of the ECMs in these vehicles use 7727 type connectors. i THINK this is a complete list, but i could be wrong.

labeled from A-D in order wherever possible.

there are a few interesting ones in there as well...

L98 Corvette
90-91 yellow/gray, red, green, brown

LT1
92-93 gray, red, green, brown

LT5
91-95 gray, red, green, brown

LQ1
94-95 gray, red, green, brown
93 orange, natural, green, blue
91-92 orange, white, green, blue

LH0
93-94 W orange, natural, green, blue
90-92 W orange, white, green, blue
89 W black, white, gray, blue

LN2 (2.2MPFI)
93 W, only uses last two plugs: green, brown

LR8 (2.5TBI)
91-92 W orange, natural, green, blue
90 W orange, natural, gray, blue

L27 (3.8Series 1)
92-93 W gray, red, green, brown
90-91 W brown, purple, red, gray

LB6
88-89 W black, white, gray, blue

LG0 (Quad4 HO)
90-91 W orange, white, green, blue

[60dgrzbelow0]

Well, technically my 24x Sensor IS bad. (the one behind the HB)...I installed a new one during the build and when I scanned it post build it was throwing a code for the 24x sensor signal loss. But my Bro's 3.4 Camaro ran with the same code for a long time and only had difficulty on starting the car up from now and then. Also, when I switch over to OBD-1 with the swap kit, that sensor will be made irrelevant anyhow, as well as the cam sensor and one of the O2 sensors, etc.

Now if your talking about the more important 3x crank sensor in the side of the block, I'm not getting a code for that on my scanner, and I didn't even replace it during the build so there's a good chance that sensor is still fine.

That last part surprises me...because I saw your images of all three brand new sensors and just assumed you replaced them ...just to be sure that having them fail at any given moment would be eliminated. I forgot that you did not have the engine on a stand where this would be so much easier to do. Without testing it... How do you really know whether or not it has been a factor in the problem of stalling?

I guess what is also puzzling me is that even with John's "Adaptive ECM" Designed Lumina Unit... It still has to rely upon knowing the dynamic positions of the crankshaft and camshaft relative to each cylinder's BTDC and ATDC to know when to feed fuel ...and how much...and when to fire the coils...and with how much to lead or lag the spark to accommodate the power curve needs as the RPMs climb the scale. So with that in mind... what sensors WILL be relevant once the new "Brain" is doing all the new thinking for the car?

FWIW... As a Mech with practically no understanding of what all these new things you are trying out will mean, I looked into getting a better understanding of the basics and this Tech Article is chock full of the whole spectrum of DIS information about the GM Car Line Series, including the MFI and SFI set ups. In addition to the interesting historical background about the development of EI from its origins at the turn of the century, there are some particular and unusual Tech Tips showing ways to investigate certain electrical issues that I've never seen before:

http://www.search-autoparts.com/searchautoparts/article/articleDetail.jsp?id=20037

[IsaacHayes]

Just the 7x(3x) crank trigger is used. The 24x and cam sensor are not used.

[tkoforpresident]

yeah, what isaac said ^^

the less sensors used, the less that can go bad so i like it.

Technically your right Bob, and I have no idea if it is the camshaft alone and not a sensor or two gone haywire causing the vehicle to stall out and idle irradically. But like robert mentioned before, we can assume that once a radical cam is installed there will be radical results. Remember, my car ran FINE before the cam install and has developed driveability issues directly after the new radical cam was installed.

I think you should just wait and see how much tuning will help out


Forced: Harness looks great imo, what is that black wrap around the wiring?

[IsaacHayes]

Friction tape.

[tkoforpresident]

So John... does this mean i'll be getting a tracking # soon?


I can't wait to get some data logs up for you guys to look at.

Edit: off topic a bit. Can I burn the current tune i have right now onto one of the spare chips i have since it's the "finished tune" at least before data logging?