Hey all, so with my car going under the knife this winter for the new motor. I decided that I am going to push the Holley install now instead of in a year or so. Wanted to start this thread as there is good information out there on the swap and I have already gone through the pinouts of the factory computer (as I will be using the oem pcm to control the dash and such still) to see what I need to keep/get rid of. But I wanted this thread so others could share their install insights and hopefully we can get this pretty full of information out there.

So for anyone that has a good understanding of wiring do's and don'ts, this should be a simple install... BUT, with every simple install, there is always the small caveats that make it slightly less simple.

Here is where I am at with the pinout removal. As I mentioned, I plan on keeping the factory dash and I am keeping the ac working as well. Not sure on ABS yet or not, even though this would be the time to get rid of it and free up some engine bay space. What I need to know more detail on is if the factory pcm needs to see anything from the Throttle Body or pedal? I know Holleys DBW harness is supposed to be used with the C6 pedal, but Current Performance has a custom harness with plenty of connector options so I can use the C5 pedal, 6 Pin throttle body plug, and they can make each lead however long I need from the Holley to the pedal or tb. Also, with the AC, I know the factory computer has idle tables that effect the compressor and how it functions. Anybody have any insight into changes to make so it will work independent of these tables?

I planned on also using Current Performances crank signal splitter, which the signal wire I will just send to pin 12 on the blue connector of the factory pcm.

I will still have the passenger airbag in the car, so that is a no go for a mounting option of the Holley. I also have the coils located in the fenders, so I don't think that will work either. I wouldn't mind seeing where everyone has theirs mounted. I would ultimately like it in the back of the car where the battery is, but I doubt there is enough harness lead for that. And if you have it mounted in the car, where did you choose to put the wires/grommet at in the firewall.

 

Was really hoping this thread would gain some more traction than it has.. haha. Well to add to it so far, I won't be starting on the install until the winter, but I tore the glovebox out yesterday trying to determine how I wanted to mount the ecu itself. Some people have suggested under the glovebox, bolting it to the frame that goes across. This is a good option, but I would really like to mount it up inside the glovebox on the aluminum roof that the airbag sits on top of. Then cut the backside of the aluminum structure for the wire harness to pass through.

I suppose another option is the side of the trans tunnel on the passenger side. Would need to cut some of the insulation out on that side. As well as do some reflective heat tape work on the inside of the tunnel as we all know it gets ridiculously hot.

 

Another question I had for anyone reading this, where has everyone grabbed the 12V key on power that the Holley requires? I know it needs to remain on while cranking.

 

https://www.corvetteforum.com/forums...ghlight=holley

 

I went straight to the ignition switch,I forgot the color wire though.

 

 

 

Unfortunately, I cannot mount the ecu there as the coils are in that location. And I would rather it be inside the car.

 

I've been debating on going to this... does this have the self tuning feature, etc? Do you still need a tuner to dial it in with this? I have a little above average knowledge with HPT... Sorry Op not trying to jack your thread just a quick thought...

 

you should get on the phon@DRIVER456 to chat about it. He’s done it successfully and competes at the drag strip with it.

 

You can mount it any where you want,Just a matter of drilling a hole to get all the cables/harness through.

 

Yes it has a self tuning feature.I had EFILive for years and looked at HPTuners,In my opinion using the Holley way is easier to tune.

 

Hey Mike,

Let me know if you need any help with the install or tuning. I'm a Holley dealer now too.

 

The "self tuning" feature is the same as a fuel trim histogram being applied to your tune, so everything else still needs attention to get it dialed in properly. I sell Haltech and Holley systems and have a systematic way of installing these into C5's and C6's that makes it much easier. All the factory gauges continue to work. No check engine light, no messages. Basically you can't tell that the factory PCM isn't running the powertrain. Even the PCM doesn't know that it's not running the show..

Bret

 

The Holley is *NOT* self-tuning. If you follow the instructions on setup, it will get the car running well enough to take it to a tuner. Of all the countless Holleys I have tuned not a single one has been even close. You will think it is "okay" because the car will run/drive mostly decent, but the difference after having someone who knows what they are doing tune it, especially with driveability/idle/cold and hot start/etc will be night and day.

 

Brent now that you have installed and run both the Haltech and the Holley, which is easier to piggy back and tune on the c5

I'm also interested in e85 tuning with the stock 04 ecm. I'm interested in taking the plunge with e85 but like a limp home if I can't find it on pump gas.

I still have my old Haltech platinum on the shelf gathering dust. Need to get that installed!!

 

Just a word of advice
1. Dont tie wires together that carry significant current. For example starter wire near holley wires is bad. Fan wires, headlights, ignition stuff, keep it way away from the holley's wires and sensitive devices.

2. Don't mount, tie strap or fix the holley ECU into place until you are absolutely done tuning and finished with the project. There are many times you will need access to the wires and box itself during the course of installation and tuning

3. pay attention particularly to the Cam and Crank trigger wiring. I advise using shielded cables, grounded at the holley ECU like a factory ECU. Also the TPS and MAP wires could stand to be shielded as well. I always take this extra step to isolate and shield these wires because some vehicles have enormous issues with EMI and you don't want to have a signal suddenly goes crazy at some particular situation. For example 6400rpm that crank trigger wires loses its perfect signal for just 0.001 seconds and it scatters the engine.

 

My swap is up and running, factory harness depinned, and factory ecu 100% happy. After talking with a forum member, who I am extremely thankful for, the key to keeping the stock ecu happy, and not throwing a reduced engine power is maintaining the factory pedal and throttle body, at least it worked for me. I am using a LS2 throttle body and C6 pedal, with the factory throttle body remote mounted on the car, and the factory gas pedal tied up under the dash.

 

I feel some of that is very redundant.. I have a katech 103 c5 throttle body on the car, the factory c5 pedal as well.. I have a harness that connects to the c5 pedal and the 6 pin later connector for the tb so I don't need the c6 pedal. I planned on removing the tac module as I see no reason for keeping it in the car.

I started tearing into the harness yesterday a bit.

 

It is just the method that worked for me. When the car did not see the factory pedal/tb/tac module, it was extremely pissed off, throwing all sorts of codes, ses, abs, tac, and reduced engine power. Got all of that working again, and it is happy. There is always more than one way to do it. Best of luck, it is a project, and can make you really think at times!