Has anyone ever completely eliminated the stock ECU? I'm curious to know what kind of issues I will have making the stock gauges work without the ecu.

Thanks
Chuck

 

Why do you want to totally do away with it. Its not like it weights alot. I am using Accel DFI and plan on keeping my ecu. I should have mine running by next week. Will pull ecu for you and see what does not work.

 

Actually, man, I dunno anymore. I don't know how this ever turned into me building a 9 second race car. But it did. I'm thinking I'll just finish doing what I'm doing to see if I can make some 9 second n/a pass's with the thing... then pull the motor back out, put in some flat tops, a mild solid roller, go back to LT1 edit, and have myself a nice street car. No more of this race car bs. I'm chopping up a beautiful 97 SS. That is pointless. If you want a race car, build a race car. But don't turn your street car into one unless you have a reason to. It's a waste of time and money... and enjoyment of a nice vehicle. I'd rather a 10 second street car than a 9 second race car.

Later
Chuck

 

Hehehe Chuck I hear you. We are shooting for the 10 Second Street car thing but it looks like 9s will not be out of the question. I am going to tune the heck out of my stock PCM before I make the dedicated hack for a after market ECU.

Good luck!

 

Odd... I did the same thing, and thought the same thing about a year ago.

 

So now the question arises, is it very difficult to hook up the Fast in conjunction with the stock ECU? I mean I know this can be done, don't think i'm stupid... Basically I'm asking if anybody has a diagram of what wires go where.

Thanks
Chuck

 

you can buy a piggyback harness that will retain the factory PCM so all your gauges work, but the FAST will control engine functions.

www.fasttrackperformance.com is where I got mine.

FWIW, I'm taking the stock PCM out completely and rewiring the car with a stand alone FAST harness.. We could probably work out a deal on the piggyback harness if you want it. I have the installation instructions too.

(I'm going with a different engine so I need to change wiring harnesses).

laterz
...Brady

 

Ahh, cool... How much do you want for it?

Later
Chuck

 

Chuck,

Do a drag car you will not regret it! There is a big difference from 10's to 9's to 8's regarding the feel and what a great rush. I have had other cars in the past that one was a backhalf car and the other was a firewall back setup and my car todate is a 25.1D chassis car and let me tell ya I have drove the others on the street and I plan to drive this new one I have. There is nothing like anything else when you pull up next to a $80,000 Viper or high end supercharged Saleen Mustang with your drag car that really shouldn't be on the street. LOL!! It's always funny how these cars always allow you to leave first and never decide to speed past you.

I have my stock ECM out of the car and I use Autometer cages in the stock dash. My whole car for the most part is functional via a control panel mounted on the top role cage bar. I use a Tim McAmis ProMod control panel.

But I can understand what your saying about being able to cruise for hours or going out of town. I loved my car and the way it drove after Lingenfelter installed the 383ci. That was endless fun from start to finish and all on pump gas.

Think it over long and hard.

 

Well I'm around fast drag cars all the time. So having my own isn't anything that really interests me. If I were to build a drag car, I'd start with another 4th gen that is a little more suited for drag racing (no t tops, less options), and build from there. And instead of an LT1 I would build a 15 degree bowtie blocked sbc.

Later
Chuck

 

Just to clarify... the only "stock gauges" that run off the stock ECM are the speedo and the tach. The oil pressure, coolant temp, fuel level and voltage comes directly from sensors that do not interface with the ECM. Tach can be driven off anything. So can speedo. I think it can be interfaced directly with the VSS using a Dakota Digital conversion box.

I kept the stock ECM with the MoTeC, because the MoTeC can not drive the stepper motor IAC valve used on the LT1. And I actually tried to keep all the emissions systems (AIR, EGR, EEC) functioning, which requires parallel sources for some of the pure resistance type loads like temperature sensors - e.g. dual IAT and dual coolant temp sensors.

You also have to remember the stock ECM looks for the Opti low res pulse, or will shut down the fuel pump, so you need an alternate source of fuel pump activation if you are getting rid of the Opti.

 

For some reason when we wired the stand alone harness into my buddies car, we lost all gauges. I'm not sure why, the wires from the sending units were left intact- and they went straight into the cab of the car.. Oh well.

FWIW, the FAST will ground the fuel pump relay You just have to rewire the coil + side of the relay to a wire that's hot in key on and cranking.
FAST even has a fuel pump prime parameter. It's easy to wire in.

laterz
...Brady

 

Fred, I was just told by Robert at NE Dyno that they are running several cars without opti's... Everything works fine except for the tach... which is easy to fix. And like Brady said, the Fast is able to control the fuel pump relay, so everything should work pretty good.

Also, did you ever think about just trying to drill a couple small holes in your throttle blades to make up for not running an IAC?


Later
Chuck

 

The Fast Track Performance piggyback harness keeps everything working even all the gauges. If you use an edist box the only thing that needs to be done when you use the piggy back harness is run the tach output from the edist to the factory ECU which is pin 13 in the red connector. That makes the tach work.

Rob

 

I am running an IAC. It's just driven off the stock PCM. Provides a good "fast idle" on startup, and comfortably drops down to the stock 800rpm setting as the coolant temp comes up.

The alternative would be to use a PWM IAC controller, and just locate it in a small bypass from the inlet air box to the plugged port (93/94 only. 95-97 uses it for PCV port) on the intake manifold under the TB. The MoTeC can drive a PWM IAC.... its just the GM stepper motor it can't drive.

I figure its time to unhook the stock PCM and get it out of the car. I don't run a speedo. And I can control the fuel pumps with the MoTeC as well.