ECU choice for OBD2

[Jeff W]

I’m shopping around for an ECU for an LS and I’m going to be emissions/OBD2 compliant. I can’t seem to figure out the whole controller thing. There’s the one that comes from GM specific to my crate motor, but it’s non-emissions compliant, and apparently they won’t sell their ECUs separately from the E-Rods due to matching serial numbers in the engine and ECU.

So how the heck does one get an OBD2 compliant ECU set up on an aftermarket LS engine in a car that never had an ECU to begin with. Anyone got experience with this?

 

[Tom]

hi Jeff, I just got a used GM E38 ecu to run my LS7 motor. My motor is only mildly modded, so it shouldn't have any issues passing emissions. Things might be a little more complicated with an E Rod motor, in NY you are not allowed to use any ECU which is not native to the engine (though I'm not sure how they check this).

 

[Jeff W]

Yeah, that’s the problem. If it’s a custom motor, how do you get a “native” ECU? It’d be easy to get a used ECU out of say a pickup truck and tune it to the engine, but I have no idea about the SN# business. My motor isn’t E-rod, just a regular GMPerfomance crate engine.

 

[Mark B.]

It really depends on the requirements for your state/county. Some counties just require that they can plug the test rig in, and it shows no errors (meaning you can just disable error reporting on the ECU for tests that you don't want/have like purge canister, etc). For this type, an E67 (like the GMPP one I use) or E38 will work fine as long as you can tune it or take it to someone who can. Other jurisdictions require specific results and even visual inspection. I'd suggest talking with a local tuner (with a good rep obviously) who is familiar with local requirements.

 

[Joel K]

Jeff, if you require full emissions compliance then you will need a factory ECU with a factory tune, and stand alone engine harness wired with the emissions components you want to use.

 

[Joel K]

Speartech inc can set you up with the ECU, tune, and harness. If you are building the car, wait till you know where everything is going to go then they will custom make the harness for you.

That is the route I went with a full emissions compliant build. Hoping to install It in October.

 

[Jeff W]

Thanks Joel, that's exactly what I'm looking for and will help get the car registered as a 2022 SLC. What sort of measurements were they looking for as "where everything is going"? According to their site they don't make custom harnesses.

 

[Joel K]

Well they have a standard layout, but I wanted things layed out in specific places so I drew out a diagram and they followed it. Ask for Justin and be clear you want full emissions.

Here is my diagram for an LT4, some of my branches are too long but better than too short...

Here is the harness…

 

[Jeff W]

Would you mind sharing your order # via PM? I can forward that and my engine info to Speartech to give them a starting point. Just subtract the intercooler/turbo related sensors. No reason to reinvent the wheel, and definitely agreed too long is better. Can't cut it longer.

 

[Tom]

there are a number of vendors who can custom build a GM harness. Speartech makes good stuff from what I know, but a little more expensive than some others. I ended up using Current Performance in FL to build mine and I'm pretty happy with it - it was built using braided loom rather than split loom, and had heat sleeve on the knock sensor leads. Had them supply a 9 or 10 foot throttle pedal harness to make the run from ECU to front firewall. They also supplied the ECU. One thing I learned subsequently is that E38 ECUs can come with two different operating systems, the newer one being more adaptable to tuning changes. So far as SN#, that was not even examined. I have a crate motor built from the block up, so it has no SN.

 

[Jeff W]

I was finally able to navigate the Byzantine NY DMV structure and find the people who actually know what the heck a self-built car is and what regulations apply to such a vehicle. The vast majority haven’t a clue and it took quite a few department transfers to get to the right division. Bonus, I got to talk to a real person! According to them, self-built cars don’t need to meet production car requirements for matched serials, however they do need to need to meet emissions equipment requirements for the specified year the vehicle is being registered as. Sure would have been nice if that info was in the homebuilt car registration package I got from them earlier this year. So that’s that, Speartech and similar setups are fine so long as they meet emissions requirements.