MY-EFI Since 2006

Professional Engine Swap Wiring Harness And ECM TCM PCM ECU Programming and Tuning Services.
Call us with your questions at 1-800-395-1208 or 518-410-3802 9AM-9PM EST or email


Frequently Asked Questions

1. How long does it take for the Engine Wiring Harness Service?  The Harness Service is done on the week that was given to you over the phone. There is usually a waiting list. You can call ahead to see how soon it can be done. It can be done sooner if requested for an aditional fee. It can also take longer such as a week if there are additional add ons or if there are several repairs to the engine harness.

2. How long does it take for the ECM PCM TCM Programming Service?  Programming only takes a day or two but is shipped with the engine wiring harness in the same box. If you only sent an ECM, then we will have it shipped back to you in 1-3 days.

3. Who do you use for shipping?  We use the United States Postal Service or USPS. All packages are shipped USPS Priority mail with more insurance than the contents are worth just in case. We have never lost a package in over 9 years.

4. When do I pay and how?  You dont have to pay until we are finished. We take credit cards over the phone or we can send you an invoice to your email address. You can then go to our online store and pay there.

5. What information do you need?  We only need your name, phone number and address on a sheet of paper in the box so we know it is yours. We will call you when it arrives and ask you several questions about your engine swap. This information is recorded by us and used when we work on the harness and or ECM.

6. What do I need to ship you?  We only need the engine wiring harness and ECM. You can keep any Fuse Blocks, ECM brackets, TAC modules, Foot Pedals and Battery Cables.

7. Is the Engine Wiring Harness labeled and have instructions?  Yes, the harness and all of its connectors and wires are labeled. The return box will have the simple instructions that identifies each connector and wire.

8. Do I have to run emissions, air conditioning, evap, egr, air pump or rear oxygen sensors?  You do not have to run any of the above mentioned emissions or air conditioning if you do not want to. You can choose to keep or delete and add in any connections you like.

9. What transmission can I run?  Most engines run a 4L60E, 4L65E, 4L70E, 4L80E, 4L85E, 6L80E, 6L90E, T56, Allison, or a stock transmission that the engine came with. Some engine harnesses and ECMs can be changed to run several different transmission. It is best to call us and we can verify if it can be run. Alot of customers can run NV3500, 700R4, Th350, TH400 and other transmissions too.

10. Is there an OBD2 or Diagnostic Port for reading trouble codes and custom tuning?  Yes, we can send the New OBD2 port attached to the engine harness or seperate to pass through a firewall. Just let us know the length needed.

11. Do I have to run the Vehicle Speed Sensor?  If you are running a 4L60E or 4L80E variant then yes. The transmission will not shift without it. If you are running a manual transmission or older automatic then no. Some newer transmissions have the VSS built into the transmission.

12. Is there a temperature output for my gauges?  Yes for 1998 and older engines. 1998 was generally the last year for a temp output wire. Most 1999 and newer vehicles had a serial data line or can bus signal to the instrument cluster for temperature instead. We can add on a 1998 temperature sensor connector and run the wire lead for a temp output. You just need to buy the 1998 LS1 3 pin temperature sensor and install it in place of the older 2 pin sensor.

13. Can you extend the engine wiring harness to put the ecm pcm in the vehicle?  We dont usually do this because of the extra time and cost it would take to make the engine harness longer. It is alot of cutting, solder and shrink tube. It is sometimes better to find a different style/length/routing engine harness that would meet your requirements or buy a new one premade that is longer.

14. Do I have to run the Mass Air Flow Sensor?  If the engine is a LT1 style engine you do not have to but it is recommended. If it is the LS1 style engine then we recommend keeping the maf sensor. We do not have a speed density tune for the LS1 based engines. Some customers have us remove the MAF connector and wiring for a turbo or supercharger build and that is fine.

15. Do I have to run the front oxygen sensors?  Yes, both left and right. We can delete the rear oxygen sensors. It will run better if you run the front sensors and get your air to fuel mixture correct. If you are running the engine in a marine application we can delete the front ones for you.

16. Are there output wires to my gauges?  Yes, there are several outputs for your check engine light, tachometer, temperature, oil pressure, vehicle speed, serial data, air conditioning request, cruise if used, torque converter lockup and park neutral switch. These output wires do not need to be used in order to run and drive.

17. If I change my axle ratio and tire size or if I dont have the size now, can I send the ECM or PCM in again at a later date to be programmed for the correct shift points?  Yes, and its free forever.. All you have to do is pay shipping to and from us.

18. Are there wire leads to the fuel pump and fans?  Yes. The harness service has 2 foot 12 gauge leads. We have an option to purchase longer wire leads to the fuel pump and fans on either relays or a fuse block for an extra fee. Just let us know how many feet of wire is needed.

19. How many wire are there to hook up?  There are usually two positive wire leads to the fans, a positive wire lead to the fuel pump, one keyed hot wire lead, an ECM or PCM Positive wire lead, and a starter relay trigger wire lead. The engine harness receives ground through the engine.

20. Is the ECM PCM or TCM locked after you program it?  No, it is unlocked. We use an unlocked version of programming software that will not lock your computer. Anyone can still access it at any time.

21. Can you program for a camshaft, supercharger, turbo or larger injectors? We cant program for major modifications but can refer you to a mail order dyno tuner that you can send your PCM. You can also get basic programming and go to a dyno at a later date after you get the engine running.

22. What information will you need when I send in the PCM and Engine Wiring Harness? I will need engine year and size, transmission, axle ratio, tire size, fan on off temperatures, octane of fuel, keep or delete a/c, emissions, oil level wiring, and sometimes much more. It really all depends on what has been changed and what you are running. I will ask you several questions and take notes on what exactly needs to be changed.

23. Will truck style injectors fit in an LS1 intake?  They are 11 or 12mm shorter than a LS1 injector so they wont really work safely. If you have a truck engine harness we can add on LS1 EV1 or LS3 EV6 injector connectors for you.

24. Can I run cable throttle on my 2007-2015 Generation 4 LS Engine instead of the Drive By Wire?  You can run cable throttle a couple ways. One is to drop the crank and press on a 24x reluctor ring instead of the 58x one. Or you can get a Lingenfelter 58x to 24x converter box. You will also need LS1 knock sensors, a camshaft sensor extension harness and a knock sensor extension harness sold by lingenfelter or racetronix. You will need a cable throttle body with the TPS and IAC sensors. Generally, it is more expensive to add cable throttle onto the newer Gen 4 engines.

25. Can I convert to cable throttle on my drive by wire engine harness? We can convert your engine wiring harness to cable throttle if it is 2007 and older and Gen 3. These engines are already 24x and can run both cable throttle and drive by wire. We can add in the tps and iac connectors and wiring. We can also rewire your oxygen sensors for the 99-02 cable throttle pcm.

26. Can my drive by wire PCM or ECM be converted to cable throttle?  The 99-02 PCMs can be programmed to cable throttle. Certain 03-07 PCMs can be converted if they have the IAC hardware. If you take the back conver off and call us we can tell you if it is cable throttle compatable. The 2007-2015 ECMs cannot be programmed to cable throttle.

27. Can I run a LS3 MAP sensor on a 99-07 Gen 3 PCM? I havent seen anyone successfully program a PCM to run the LS3 MAP sensor. It is best to fit a LS2 MAP sensor in place of the LS1 MAP sensor.