Stock Harness to Holley Adapter?

[TireFryer]

Hear me out. Couldn’t one create an adapter for our cars to run a Holley ECU in our cars similar to the ms3 PNP? Some of us like the ability to plug in a ms3 and have tons of tune ability, but the i/o is very limited. I know the ECU Gn is also a good alternative, but a lot like Holley. Isn’t all that the Casper’s or Cruz harness is? Takes the stock ecu sensors and pins them to the Holley pinout and adds all the new wiring and relays? Couldn’t you just make a small harness to convert the stock ecu plugs, and make a harness to pin them to a Holley style? So you could keep all the stock harness and just plug in a Holley, tune it and go? Surprised this hasn’t been done yet.. I may take this on as a project to see if it can be done for us younger Buick enthusiasts that don’t have 6 grand to spend on a complete overhaul..

 

[THensley]

you should have enough worms in that can to fish for the rest of your young life.
If your doing it on the cheep buy a universal harness from Holley, don't try to fix a 40 year old GM harness
Just my 2 cents, My harness was junk and repaired two many times to even think about a ECUGN . I was ordering a OE from Caspers but went Holley instead of OE. If my harness was good I would consider ECUGN. Im very happy with my Caspers harness for Holley and Im too old to build my own.

 

[GNVenom]

The main problem with using an adapter is that the original wiring on our turbo cars commonly fails due to deteriorating connections, oxidized copper, unsealed connector failure, etc. And the Holley has many extra inputs and outputs that won't interface with the basically simple stock turbo harness. Power feeds, O2 wideband connections, etc. add to the complexity of trying to interface to the factory wiring. Much better to rip up and replace at this point.

 

[BEATAV8]

I’ve not seen a Holley connected to a stock ignition module? Always seem to be set up with coil on plug. You’d really need to butcher a stock harness for that. Not to mention the missing items like the wideband that would need to be added.

It would be a mess of unnecessary connections at the stock ECU connector, and a bunch of added items going around that. Better off just eliminating the stock ECU connector and replacing it with Holley ECU connectors.

For example on the ECUGN, the wideband and the coil on plug harness come in through their own harnesses and plug into the side of the ECU. They don’t go through the stock connector

 

[Chuck Leeper]

I Have been involved with several Holley installs on other cars.
Buying a "complete system" is the least expensive.
However, "ala carte" is more user/installer friendly..
Were we doing the last system again, we would bite the bullet with these choices.
ECU, unterminated main harness, handheld unit.
Modifying a specific harness is a total PITA. The unterm harness is plenty long enough to put the ECU
where you want it.

 

[TireFryer]

Thanks to all for the input. Answered some of the questions I had. I’m already having some issues with losing cam sync. May be time to bit the bullet and get a harness and new ecu.

 

[Mr.Spool]

Surprised this hasn’t been done yet.. I may take this on as a project to see if it can be done for us younger Buick enthusiasts that don’t have 6 grand to spend on a complete overhaul..

The reason it's not done is because when your spending the kind of money on a top notch computer system its wise to want all new stuff.
The labor involved and the car on the newer parts is a computer reset of the whole car.
If your stock computer is working and getting the job done then stick with that.
Especially if you know that setup.
Every computer holley,fuelteck,ms3pro/gn ecu,fast can all work it's up to the tuner,period.
There are advantages in certain systems over the other in terms of range and speed mainly in the traction control system.
But that's another topic.

 

[mblum]

In the end I don't think you will regret getting a new harness. While I don't have a Holley or any other aftermarket ECU, I did just replace the stock harness on my 86 GN with a new Casper's harness. My Stock harness "appeared" to be in great shape from the outside appearance. Last year I started having some random electrical issues that would come and go, plus some continuity issues. I was finding corrosion inside the harness and terminals that were no longer tight in their connectors. I got fed up with it and put in a new harness. Man, what a difference, car runs so much better, and I thought it ran well before.

I know the aftermarket ECU's are powerful and can do a lot that the stock ECU can not. I do hear of a lot of success stories of people switching to an aftermarket ECU and them saying the car runs so much better. I wonder how much of that improvement has to do with the new engine harness that was installed with that new ECU.

I'm not taking away from the aftermarket stuff, the capabilities are just bad ass and they certainly have their place, and I definitely think I will end up there myself in the future, epically when I build an engine. But for now at my power level I am happy with the stock ECU and new harness.

Just my $.02 regarding harnesses.

 

[Reggie West]

Acccording to Caspers, they are working on a harness to use with the MS3 Pro not the Plug N Play. It is not ready yet and no idea when.

If you want a new harness to work with the Plug N Play, Cruz said he would build one. I have not ordered one yet to do it but I have not had anyone needing it.

I am in the middle of putting in a MS3 PNP and DD-EFI dash on well built car right now. It is getting all the goodies to with it. Ill keep you posted.