How to make the move to an aftermarket ECU

By J.G. Pasterjak
Dec 31, 2023 | Shop Work, ECU, Buyer's Guide, GRM+ | Posted in Shop Work , Electronics & Electrical Systems , Buyer's Guides | From the Nov. 2021 issue | Never miss an article

Photography Credit: Kevin Adolf

In less than a generation–so, in little more than a couple of decades–the image of an engine tuning expert has shifted completely. It used to be a guy in greasy overalls armed with a set of vacuum gauges and a great ear. Now it’s someone–maybe not even in the same room or state as the machine they’re tuning–hovering over a …

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Hungary Bill (Forum Supporter)
Hungary Bill (Forum Supporter) GRM+ Memberand PowerDork
10/22/21 7:12 a.m.

It might just be me, but I'm getting the "oops, we're lost" page

BA5 GRM+ Memberand Reader
10/22/21 8:44 a.m.

This article came at a good time.  I'm looking into the what/why/how for the ECU for my project.

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
10/22/21 4:43 p.m.

Been remote tuning a car in the UK and another in Alaska this week. Both from the comfort of my lab in Pa. 

Junghole SuperDork
10/22/21 11:51 p.m.

Or do like me:  step 1) buy aftermarket ECU. 

Step 2) ask GRM for help  

step3) sell Ecu to a cringey kid on Facebook. 

Cactus HalfDork
10/23/21 12:04 p.m.

In reply to Junghole :

Or what I did 1) buy a megasquirt for a turbo project

2) lose interest

3) most recent 5 vehicle purchases are all diesel or carbureted

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
10/23/21 1:33 p.m.

Did I miss the elephant in the room? Any car newer than a quarter century runs OBD-II. No aftermarket ECU supports it. This can limit your ability to register the car and your resale market. It may also mean that your supplier may not be around to support you in the future if they are run out of business for selling emissions bypass parts. 

Buying an ECU from a supplier that has deep experience in your specific application is far better than relying on forums. Forums are populated by hundreds of people with experience on one car. A specialist like AIM has experience with hundreds of examples. It makes a massive difference in the quality of the base map, especially since most individuals just accept driveability problems because it's hard. Think about all the test drive reports you've seen of a car with an aftermarket ecu where it's acknowledged that the tune "isn't finished". 

Aftermarket ECUs definitely have their place. I have them on a couple of my cars. I would much rather work with an ECU than a carb because I can ask it questions :) But it's a bigger step than a lot of people make it out to be. 

MrFancypants Reader
10/23/21 1:45 p.m.
Keith Tanner said:

I would much rather work with an ECU than a carb because I can ask it questions :) But it's a bigger step than a lot of people make it out to be. 

That's funny. Reminds of of every conversation I've had with older enthusiasts who look at my car and say it's too complicated to deal with when something breaks, then I show them the scan tool tied to my phone that tells me precisely what's wrong with the car when I have a problem. Every time my car has failed me I've been able to diagnose the problem perfectly on the first try, and I'm a complete amateur.



Run_Away GRM+ Memberand Dork
10/23/21 1:46 p.m.

In reply to BA5 :

I vote FuelTech for your Lude!

BA5 GRM+ Memberand Reader
10/23/21 8:14 p.m.
Run_Away said:

In reply to BA5 :

I vote FuelTech for your Lude!

Might be a little rich for my build. I'm looking at MS.

Plus they're the only one I've looked at so far that even suggest they support the Honda J series crank trigger, which is apparently a kind of oddball setup.

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
10/24/21 6:33 a.m.

FT is workable for guys that hit the gas, then pull the chute. It annoys me for much else. 

The j trigger is supported by a few but def not common. We have done two on ms3 pro so far one na and one boosted. 

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