Andreas_91GTA

Yes, 3-4 is as perfect as it can be!

BobLarryPaul

Did you figure out the factory speedo? I am just finishing up a 38350 on an 89 GTA and it's my last hurdle.

Looks like you used the Dakota digital box, If it did work can you give me a quick and dirty walk through of how you wired it?

Beater79TA

89 GTA should be an electronic speedo. That means it should be a simple splice of the output wire from the Fitech to the speedo wire from the factory ECM to the gauges which is located under the passenger side of the dash. Then set the FiTech output to 4000ppm. At least that's what it took to set up the FiTech LS system on our 88 GTA. Then it's just a calibration of the FiTech tune to match your tranmission and gears to the ECU is seeing the right speed.

Komet

I found the wire that goes directly to the speedometer in my gmt400 and hooked it up to the speedo output of the FiTech harness, works fine. Ironically I couldn't get the tach output to work, and tech support couldn't tell me what their settings mean, so I took tach output directly from the coil and piped it to the gauge which works fine.

ratfink6923

iTrader: (2)

This thread has me wondering if I should ditch my plans for the 0411/OBDII swap and just go this direction. I have so far been unable to find an unmolested vortec 5.7 harness, and when all is said and done, the investment wouldn't be too much lower. I do like the ability to tune more closely with HP tuners and a true sequential fire. But this seems more economical and far simpler.

I'm open to any input anyone has to offer

BobLarryPaul

Thanks for the response I'll make that happen this afternoon, fingers crossed I am free of this car after that lol.

BobLarryPaul

I ended up taking a few days off this project to finish another, now that I am back to it I have it all together now however I dont see anything in the handheld or on the PC software to adjust PPM what ids it listed under? I also have the speedo output from the Fitech attached to the Speedo wire that ran to the ECM (Small Plug Pin A10 Brown) from the double connector under the passenger side dash is that correct?

Also with it hooked up like this when the car starts first starts moving the Security light flashes like its being pulsed then eventually just lights up solid with more speed added, I have the car strapped to the shop dyno so you get to notice alot of this stuff.

BobLarryPaul

I was on the wrong speedo wire you do not go to the A10 wire you go over to the VSS buffer and attach the Fitech Speedo output to the Speedometer wire of that unit easy to do., I also figured out the speedo calibration immediately after that/had already figured it out unknowingly so it was bang on as soon as I fed it signal.

Wray

I posted last year, but have lost track of this thread for a while.
I was looking how to keep both the speedometer and cruise control working using the FiTech system
I asked Fi Tech technical help but they couldn't tell me how to make it work and keeping all the creature comforts working.
This is our travel car for car events around the south east.

I have a very original 31K miles 1991 Z28 5.7L that is still in stock form and runs and drives great.
I was looking into FiTech to up grade the old computer and and old programing to something in the 21st century.
Since then other car projects have occupied my time except having to replace the old rear exhaust on the Camaro when I had to drop the fuel tank and replace the fuel pump.
I also replaced the good original fuel sending unit with a new aftermarket part and now fuel level reading is very inaccurate and way off. Bummer!!!

I talked to Dakota Digital and they were very helpful.
They said they have a simple converter box and gave the details on how to hook it up and keep both the speedometer and cruise control working using the FiTech computer.
On this generation vehicle, it was relatively simple.
The speed signal from the VSS is split and changed by their converter box.
One properly changed signal is sent to the ECM/FiTech computer and the other signal is sent to the original Cruise Control module.
Dakota Digital was very knowledgeable of the different signals being used where FiTech said they didn't know.

This post has some useful information for me if I get around to bringing the 1991 computer and program up to 21st century technology.
Sometimes it can be difficult when people are posting about different years and modified combinations.

Komet

I would highly recommend not swapping out the ecm on a stock engine. You will never achieve the safety and reliability of the factory tune with the FiTech. The main advantage of a self-learning system is the ease of adapting to custom configurations when compared to the factory method of burning and swapping chips.

Regarding the Dakota Digital box, I would try to split the VSS signal with a piggybacked connector at the VSS first. You might be able to just reuse the GM DRAC for gauges and cruise control and not worry about accessory output from the FiTech ecm.

C305

iTrader: (2)

Hey just recieved my fitech tpi standalone kit for my install I basically unplugged the original harness and laid in the new harness starting at fuel injectors I was just wondering for all the stuff the fitech replaces did you cut out those sensors from original harness or just pull back and tie out the way. I am thinking its alot of wires to hide away like all the original fan/fuel bulky relays and maybe about wires shorting together that are cut. Let me know if you have any ideas thanks.

sublimed

I purchased a donor v6 harness off ebay and separated the loom. From memory I needed to keep the oil pressure witch, ignition coil, gauge temp sender, AC components, power distribution and grounding, brake pedal switch, I kept the original tach output and fed the speedo signal through the airbag pin.

C305

iTrader: (2)

Yes a spare harness is something I've thought about aswell, also where did you guys place the fitech ecm in the engine compartment? Is it long enough harness to make it into the vehicle where OEM ecm sits? I know once those original relays are removed by the brake booster I can maybe make a mounting bracket their for the ecm and supplies fuseblock and add 2 more relays for the fans

sublimed

I have seen them placed by the factory relays. I have seen people cut a new hole where the HVAC harness goes through the firewall. It is, unfortunately, too short to go through the factory location.

sublimed

I cut down a factory V6 harness. Most of the ecm harness can be cut away. All of this information is for a 91-92 harness.

The fitech has connections for brake switch, tach, speedo, fan 1, fan 2, key on power, fuel pump.

Items that are left on the c100 connector for gauges.

A4 power distribution - Red to battery
A5 brake warning goes to master cylinder - Tan
A7 Emissions Controls - Pink Black +12v with key

B4 Starter Solenoid Wire - Big Purple Wire
B5 M/T Back Lights - Dark Blue

C4 M/T backup Lights - Light Green
C7 Engine Ground - Black White no start without

D4 TBI VSS sensor. -Yellow mine did not have
D6 Tachometer - White I did not connect to fitech. Kept on coil connection.

E4 TBI VSS Sensor - Purple mine did not have
E5 Oil Pressure Gauge - Tan Goes to oil pressure sender by the oil filter.
E7 Engine Torque Converter - Purple connects to fitech brake switch.

F4 Engine Ignition - Pink goes to coil - power on with key
F5 Water Temp Gauge - Green - Driver side head sensor.
F8 Air Bag - Black White - Ground

G4 fuel pump - Gray - Connects to fitech fuel pump relay. I left the lead from the oil pressure switch. The oil pressure switch provides +12v if the relay fails.

G5 Power distribution - Red to Battery
G8 Fan Relay - Brown - Provides Key on Power to Fan relay.

I connected the I/P Pin D connector by the factory ECM to the fitech speedo out. It was pin D. Ran this wire through the factory ECM wire passthrough in the passenger fender.

The Factory relays on line seem all to be Dark Green and White. I connected factory fan relay to fan 1 on the dark green.

I did wire in the factory A/C connectors just in case I decide to keep it. The V6 has a A/C relay. This wire trail also runs to power steering switch. The TPI cars did not have this switch. I changed the wires around a little so the ground calls the relay and tell the fitech the AC is on.

Wired a second fan relay in down by the distribution block. Used the A7 pin for the key on for this relay and triggered it off the Fan 2 wire.

Key on power to fitech was provided to via the old fuel pump relay.

C305

iTrader: (2)

Yes nice write up I just wrote out my connection notes today you beat me to it haha. My info is for a 91 aswell, all the wires ran under the fender are what is to be removed from original harness everything above fender im keeping and the fitech stuff is all routed starting on drivers side by booster

white from ign coil to my digital gauges works good I was thinking of not connecting to fitech aswell but doesn't the fitech need to know what the rpm is also?


The original fuel pump relay dark green/white runs through ecm and inside the ecm has a internal relay that energizes for 2 seconds with key in run then continues to engergize aslong as their is a ignition pulse

The coolant fan relay 1
brown wire hot in run fuse power + port D
Dark green /white ground signal/switch comes from ecm port F
orange hot at all times port E
black/red to fan 1 port A

coolant fan relay 2
brown wire hot in run fuse power + port D
grey wire ground signal/switch comes from
single wire coolant fan switch/ac switch/ecm port F
Orange hot all times port E
Black/pink to highspeed fan port A

The original cooling fan relays are too bulky so I am going to replace them with generic 30amp relays

i will cut out the original fuel pump relay and only keep the grey wire to feed the fuel pump
the rest of the harness I will tie back and loom it and tie close to the factory wire pass through passenger fender side

sublimed

I think the Fitech gets the tach signal from the distributor connection plug. I think the white from the fitech is an output only. Could be wrong…lol

Andreas_91GTA

Correct. Speedo and tach are outputs.

C305

iTrader: (2)

Yea your right about the tachometer out signal I have a question about the fuel pump relay
are you still using the oem fuel pump relay to control fuel pump you mentioned leaving the lead from the oil pressure switch which provides 12v or did you run that to the fitech fuel pump relay for extra safety feature

their is a pink/black wire that is hot in run that is shared for all the emission stuff like egr/air diverter/ canister purge I dont run any of the emission so is that a good source for keyon and cranking power supply? Its also has a 10amp fuse, I am trying to stay away from the ignition coil as a source because I may be running msd

Komet

FiTech recommends you run the factory small cap HEI with divorced coil for ignition.

sublimed

I bypassed the fuel pump relay. I ran the fitec orange wire to the junction for the gray wire between the oil pressure switch and the c100 connector. I left the gray wire connected to the fuel pressure switch/sender. I know people say that it is safe switch to cut fuel pressure if the engine has no oil pressure. I do not think that is accurate. I had a factory fuel pump relay fail. The car would still turn on after some cranking then run perfect. The car just did not have prime and would run after the oil pressure switch triggered it.

I do believe the pink/black emissions wire stays hot even during cranking. From what I can tell that circuit powers the brake switch and the injector drivers. I used that circuit for the key on for the secondary fan relay. I also used it to trigger a relay for the key on to the Fitec. I ran a new fused lead to the battery for the key on Fitec. This relay replaced the fuel pump relay. Now that I’m done it seems like overkill….lol.

I originally was going to put the secondary fan relay in the 91-92 tpi location. I then realized how close the fan connector was to the power distribution on the starter size. In an attempt to limit the amount of big gauge wires going behind the motor I just grabbed fused power over on the starter side and ran the pink/black wire and the fitech trigger down by the fan connector.




Do you have the service manual? If not I can upload any pictures you may need.

wruiz

For those who installed the 38350, where did you connect the red key wire and the orange fuel pump wire?

sublimed

You will need to grab the wire that goes to the fuel pump. I have no idea what year yours is. What I do know is you can grab it at the oil pressure switch or the fuel pump relay.

I used a wire of my c100 connector called Emissions for the key on power.

wruiz

Thanks!!

wruiz

Hi there,
I did not see any wiring for oil pressure in the fithech 38350. How should I montor oil pressure? Thanks

Andreas_91GTA

Stock dash gauge, or don't you have one?

wruiz

Yes, I do, but I assumed the fitech had a dedicated wire for oil pressure. It does have for coolant temp, knock, O2, MAP, air temp but not oil pressure.

Andreas_91GTA

Ah, ok. No the oil pressure is still monitored by the car.

wruiz

OK, thanks

wruiz

I have pretty much figured out where all the FiTech wiring goes. But not sure which connector/cable goes in the circled connector in the pic below. I know there is a cable that connects the distributor to the coil’s right side connector. Should I plug in the factory cable? See pic.