Originally Posted by 5 Liter Eater

The purpose of this thread is to discuss retrofitting a C5 with another compatible PCM with the flex fuel tables and setting up the tables to do just that; determine the ethanol content and alter stoich to in-tern alter fueling based on the content. Also to add or remove timing based on ethanol content.

Sure an aftermarket system with closed loop WOT is better but there are plenty of gen4 PCM guys making tons of power on varying levels of corn and the PCM adjusts fuel and timing based on the ethanol content in closed loop or open loop. Granted it's not correcting fueling at WOT in open loop but it knows the ethanol content and it knows how to adjust the fuel so if you're commanding .8 lambda you get it on pump or corn or anywhere in between. I haven't seen mine differ much. EG if I dial my tune in on 93 and then run the same boost on corn I don't have to alter my VE.

Originally Posted by Milan

LOL bro did you even read the first post?

Just because it can be done doesn't mean it should be or it's the optimal way. The factory PCM is great for the average supercharged car but with the standalone options out there now I don't see the purpose of keeping the stock ECU for anything but gauges when approaching something like this.

OP already has a Halltech, 99% sure Bret makes a PnP harness for it...I have no clue why people in here are harping on the getting flex fuel to work with the factory PCM when there is a proven solution out there that is a million times better. I have no clue what his prices are but in the grand scheme of making power I'm sure it's pretty affordable....

Originally Posted by Rkreigh

you are absolutely right but let me tell you where the interest lies. As the OEM ecms get more sophisticated they start to "sneak up" on the capability of the Haltech S2000 at a lower price point and I don't want to spend 4k every time I build a car. In this case I've got a sunk cost so I'm for sure going to use the Haltech, but as the OEM system could be upgraded to do things like

tranny control (already there, and programmable, missing from haltech)

dual wide bands (with more sophistication I'd love to see an OS that could do true wide band fuel corrections, a big plus on the aftermarket stuff)

flex fuel (already there)

so if I could somehow "bridge the gap" and get more out of the OEM solution it sure looks good.

the Haltech stuff is top shelf, but it also broke the bank a bit as well.

thanks for the feedback! It's a viable option to take a more modern ECM and "backdate it" into the C5 architecture and make everything work. Shucks, will all the complexity of this stuff I see some folks just piggy back a whole separate fuel system and set of injectors and another dedicated ECM (could be stock) to run pure alchy with another pump

since the c5 fuel system is such a pain, this seems to be a cool approach.

this is something I'm also interested in learning more about for the newer direct injection engines (I have a sky redline and hope to have a c7 or 8 someday) as this helps the direct injection cars that have maxed out the fuel systems. I'm interested in tuning when you "layer" a standalone ECM and injectors on top of the factory system

folks in fla built a cool turbo c7 on the z06 platform where they used a standalone haltech and additional 8 injectors on a custom intake to provide fueling under boost and they used pure meth

seems to me best of both worlds and easier to fit into the corvette design. OEM tuning with wide band and direct injection alchy under wide band control for fuel under boost

complicated I know, but indulge me

Originally Posted by Milan

LOL bro did you even read the first post?

Just because it can be done doesn't mean it should be or it's the optimal way. The factory PCM is great for the average supercharged car but with the standalone options out there now I don't see the purpose of keeping the stock ECU for anything but gauges when approaching something like this.

OP already has a Halltech, 99% sure Bret makes a PnP harness for it...I have no clue why people in here are harping on the getting flex fuel to work with the factory PCM when there is a proven solution out there that is a million times better. I have no clue what his prices are but in the grand scheme of making power I'm sure it's pretty affordable....

Originally Posted by Milan

That's why I don't think there will ever be a better car made then the C6 ZR1....

Originally Posted by 5 Liter Eater

The only issue (aside from carbon buildup) with DI is that no one makes larger DI injectors and even DI pump upgrades are hard to come by. So power is limited without adding a secondary injection system. But you're saying you'd rather own a C6 because you can throw huge injectors in it to hit a power goal rather than own, say, a Procharged C7Z because you'd have to add a secondary injection system to meet that same goal? Big power GTR's have an extra set of injectors (most also running on corn) and later model (~'12+) UR Lambos and R8's are DI and use secondary injectors in the intake plenum. Granted these are using aftermarket ECU's to accomplish this, and we know you're a fan of aftermarket ECU's so why not like DI for big power? DI affords more timing and leaner mixture. It's more efficient than spraying fuel onto an intake valve. It's a good thing.

Originally Posted by 5 Liter Eater

UR/Calvo/DP all use Motec, and Prospeed (formerly D3) is even migrating from ProEFI to Motec. Some lesser known shops use Syvecs.

Originally Posted by Rkreigh

OK, I'm convinced that the Haltech S2000 is the way to go and now I'm focused on seeing if Brett has support for the wiring harness

that would be great!

I have a fresh short block ready to go and now is the time to start to get ready for spring!

Thanks for the advice

I'm also interested in upgrading the fuel system. I'm looking at a bosch 450 intank, and another magnafuel external commanded by the Hatech to take care of the fueling

I'm using FIC 127 bosch injectors, and plan on plumbing direct port alchy with the haltech controlling the pump pressure and actifvation
with the amp box on a channel

also working on a turbo system upgrade at the same time with 6 bolt heads. should be fun.

Originally Posted by LTstewy8

When you talk to Bret about the haltech, ask him about his multiple Walbro 450 pump setups.

Originally Posted by Rkreigh

OK, I'm convinced that the Haltech S2000 is the way to go and now I'm focused on seeing if Brett has support for the wiring harness

that would be great!

I have a fresh short block ready to go and now is the time to start to get ready for spring!

Thanks for the advice

I'm also interested in upgrading the fuel system. I'm looking at a bosch 450 intank, and another magnafuel external commanded by the Hatech to take care of the fueling

I'm using FIC 127 bosch injectors, and plan on plumbing direct port alchy with the haltech controlling the pump pressure and actifvation
with the amp box on a channel

also working on a turbo system upgrade at the same time with 6 bolt heads. should be fun.

Originally Posted by BLOWNBLUEZ06

Nobody makes a true plug and play C5 setup because the PCM plug manufacturer either doesn't exist or doesn't offer them. Many have tried to pursue getting plugs done with no good result. It seems to be cost prohibitive. My method allows you to jump over to your aftermarket ECU and jump back in a relatively short period of time if you want or need to for any reason. It's time consuming, but it works well. I also have a front wheel speed sensor kit that I make for C5's and C6's that's needed for traction control strategies to work best.

Originally Posted by Podium

What do you mean 'jump back and forth"? Just wondering. Also, can you not use the ABS signal for traction control? I may have to give you a call on Haltech set up and pricing.

Originally Posted by BLOWNBLUEZ06

I often prefer to set "stand alone" EFI ECU's up in a way where they can be reverted back to allow the stock PCM to operate the car in a relatively easy way. It takes extra time, but some car owners consider it worthwhile.

While playing with the C5's electronics, I quickly figured out how to tap into the factory wheel speed sensor, but tapping into it while allowing it to remain a part of the factory ABS didn't come so easily and I chose not to invest the time because I already had a good idea in place for an independent sensor. Besides, the last thing I want to do is have someone expect me to accept full liability for interfering with the factory ABS system after they have a bad day with their car.

I have sold systems to people that had no real experience with wiring and zero experience with tuning. The difference between me and the rest is typically the fact that I support my sales with unparalleled support, spending hours on the phone. I also include all the little tools and parts to help create the best chance for success. Believe it or not, I prefer to sell less so that I'm able to support customers completely.

Let me know if I can help.

Originally Posted by TTBlueZ06

first of all you need an 04 express van pcm "p59" with any of these serv number and hardware no.

2004: Serv. No. 12586243 with Hwd. No. 12583659
2005-2006: Serv. No. 12589462 with Hwd. No. 12589161
2007: Serv. No. 12602801 with Hwd. No. 12589161

since you arent converting to a cable throttle body (i presume) then all you need to do now is get a tune for your setup and to get the flex fuel sensor and to pin it to the computer. If you are going to use the oil pressure switch and oxygen sensors then you need to do the following :
"If you have a RED/BLUE connector PCM, you CAN use this pcm on a 03+ harness (GREEN/BLUE connector) with cable throttle, with a few simple modifications. The only thing that needs changed, other then what was talked about above, is some of the oxygen sensor wiring. On the 2003+ blue/green connector PCM's, the PCM supplies a GROUND for the oxygen sensor heater's, and 12v+ comes from the fuse block. In the 99-02, power and ground is fed directly to the o2 sensor heaters. To make the changes needed to 2003+ blue/green harness, to work with a blue/red computer is this:

REMOVE: BLUE PCM connector pins: 24,27,64,67. These should all be black with white stripes. These were extra ground wires provided to the 03+ pcm so it could control ground to the o2 heaters. The 99-02 pcm does not need these. Just pull the pins out, don't cut anything yet, we need to hook these to a few other wires we pull out of the PCM connectors.

Next we need to remove the wires from the PCM connector that go to the oxygen sensor heater control. There are 4 wires, one for each oxygen sensor. If you are only using front oxygen sensors in you conversion, omit anything to do with Sensor 2.

Bank 1 Sensor 1 - BLACK/WHITE - GREEN connector pin 72

Bank 1 Sensor 2 - BROWN - GREEN connector pin 52 - after CAT o2 sensor

Bank 2 Sensor 1 - LT GREEN - GREEN connector pin 74

Bank 2 Sensor 2 - RED/WHITE - GREEN connector pin 53 - after CAT o2 sensor

Now, you should have 4 ground wires, and 2 (or 4) oxygen sensor heater control wires pulled from the PCM connectors.

You need to locate the 4 tan oxygen sensor low reference wires going into the BLUE pcm connector. If just using front o2 sensors, its BLUE pins 26 and 29. If also using rear o2 sensors, add pins 25 and 28. These wires will always be TAN and may have a white stripe. The easiest way I can think of to splice into these, is pull the pin out (REMEMBER WHERE IT GOES BACK) remove some insulation with a knife, solider on a wire, and slip some heat shrink up and past the terminal and shrink the heat shrink down over the splice. Then reinstall the pin in its original location. Leave about 12" of wire loose for each wire you splice into. Do this for all the o2 sensors you will be using.

So at this point. You should have 4 black/white ground wires loose. 2 to 4 oxygen sensor heater control wires loose, and 2 to 4 wires going to each of the TAN wires. All of these wires need hooked together in a big splice pack. First get some larger heat shrink, 1/4 or 5/16 should work. Put about 4 inch long piece of heat shrink over all 4 ground wires. Next strip off about 1-2 inches of insulation off all your wires. Start hooking them together end to end, you should be able to solider all these together, and slip the heat shrink over when done.

The last step, is to make the connectors fit inside the PCM. This will require cutting the rib off the GREEN plastic terminal cover, so it will fit in the RED pcm socket.

You will need to use oxygen sensors for a 2002 chevy truck, 5.3L, will be a white plastic connector, and will plug right into the 03+ harness without changing plugs."


You will need a FF sensor and this pigtail connector

you will need to plumb this sensor in the return line to prevent any restriction as its a 3/8" diameter orifice.

once plumbed, the wiring will need to be plugged in the sensor and the other end will be cut off.

wire A will go in pin 56 in the BLUE connector in your computer.

wire B (the middle one) goes to a switched power source.

Wire c goes to just any ground.

The rest you will need your tuner to activate the sensor and populate the flex fuel tables. After you have done this, your tuner should be able to work out the kinks and all that good stuff, you should have flex fuel capability, 3 bar, and fueling and timing on the fly.