September 20, 2021

Using an Evo 8/3G Eclipse ECU in a DSM: By [SPOOLIGAN]

I am starting this post with the intention to simply help myself document any and all information I find throughout my own Evo 8 ECU–>1G DSM process. There is a sufficient amount of information out there on the web between DSMtuners, EvolutionM, DSMtalk, club3G, the GVR4 forums, etc. But the information is amazingly spotty at best and takes a LOT of time shuffling through it all. Including the 40+ page long threads which most of the information lies in.

There are several different combinations and variables that affect you and your exact setup.

  • 1G vs. 2G chassis
  • 1G CAS vs. 2Ga cam/crank sensors vs. 2Gb cam/crank sensors
  • 1G MAF vs. 2G MAF vs. 3G MAF vs. Evo MAF vs. GM MAF-T, vs. SD
  • DSM 450cc fuel injectors vs. Evo fuel injectors vs. aftermarket fuel injectors
  • Evo ECU vs. 3G vs. other similar ECU
  • Ton’s of other stuff.

Over the years, I have tried contributing to our community via Eat Sleep DSM (website/social media groups/pages) and this is no different. I want to use the Evo ECU for many reasons. I used a Blackbox in my 2G and fell in love with ECUflash/EVOscan, though it does also have its downsides. I think the biggest reason why I want to use the Evo ECU is to learn more about it and hopefully clear things up for others that find future interest in the swap.

A lot of people put a ton of effort into giving us another option for tuning over the years. ECMlink, Jackal, Ostrich, Ceddy, Tephra, etc. Some of us take their work for granite or don’t even consider it at all. I would like to promote their efforts, more importantly the efforts of those that contributed to the Evo ECU stuff.

A little background about my exact build that I am using the Evo ECU in. It’s a 92 GSX, bought it as a shell back in October of 2015. Since then, I have been building it while recovering from what should have been a fatal accident in my 2G. See project log for more details. I am using an Evo III 16G (for now until the car is up and running with all the bugs worked out, then switch to a Holset setup), RC 550’s (again for now, have FIC 1600’s ready to go in), 2G MAF (for now, switching to SD in the future).

I have done a wire tuck, fuse box relocation, battery relocation, deletes (AC, cruise, PS, ABS, heater core, windshield wipers, emissions, EGR, FIAV, IAC, etc.), with a built-ish 6 bolt. I have been doing way too many things at once, which is why I am sticking with a very basic setup with the small turbo, injectors, and MAF. I don’t want to add to the list of things I have to configure. One problem directly affects the rest of the setup in some way.

Now, onto the good stuff.


I am using a 3G Eclipse ECU (2001, i4, manual trans). Contrary to what I have found online, the ECU pinout’s between the Evo ECU and 3G ECU are the same. So if you stumble upon this information like I did, don’t believe it because it’s not true. I have successfully put a 3G Eclipse ECU in my DSM using a patch harness built for an Evo 8 ECU. So, the pinout’s are indeed the same. You may also find that it is near impossible to find an actual pinout diagram on the internet for the 3G Eclipse ECU with the 4 cylinder engine. The Evo 8 ECU pinout diagram is much easier to find, so use this when building your patch harness.

There is, however, ONE major difference between the Evo ECU and 3G ECU. Before I touch on that, let me specify which 3G ECU will work since there are a few different types of ECU’s available for the 3G. The only 3G ECU that will work, is out of the 2001-2005 3G Eclipse with the 4 cylinder engine and manual transmission. None of the V6 3G ECU’s have a compatible ECU nor does any automatic 3G.

Now, the major difference between the Evo ECU and the 3G ECU. The Evo ECU’s have a pin for the BCS (Boost Control Solenoid/Turbo Wastegate Solenoid). This pin resides in pin #11 of the Evo ECU. Pin #11 in the 3G ECU is empty. With pin #11 being empty in the 3G ECU, the only thing this ECU wouldn’t be capable of doing that the Evo ECU can, is boost-by-gear using an electronic boost controller. Now, if you are like me and use a MBC (Manual Boost Controller) anyway, you will never suffer any affects from the lack of the pin.

Once you flash an Evo ROM onto a 3G ECU, it essentially becomes an Evo ECU. The really good thing about using a 3G ECU is that you can pick one up for dirt cheap, if not free, from a junk yard, craigslist, Facebook Groups, etc. The Evo ECU’s aren’t that expensive though themselves. Prices of an Evo ECU range anywhere between $100-$200, unless you shop on eBay in which case you will find the Evo ECU’s go for over $300. Also, be sure you use an Evo 8 ECU, not an Evo 9 or any of the others.

The other thing that the missing pin would hinder is the lack of a functional stock boost gauge. Not that that is a big deal or anything because they are basically useless, but I am just throwing that out there. But, this also means that the stock boost gauge will not work for the “knock” tool fuction, which will cause your stock boost gauge to rise when knock is detected by the ECU. This is a pretty neat feature that ECUflash offers, as does ECMlink.


I have found that different setups may require you to change your firing order. While I have seen some say you have to use the Evo firing order (1342), this is incorrect, in my case anyway. The only thing I could see forcing you to switch firing orders is dependent on which CAS (Cam Angle Sensor) you are using on your DSM. With my 92 GSX and my 1G CAS, I’m using the regular 4123 DSM firing order. Some 2G guys with different combinations of CAS’s have been known to use 3214 (the backwards DSM firing order).








A patch harness is highly recommended, more so for the 1G guys like me. There are several pins that need to be swapped on the 1G harness in order to match up to the pins on the Evo ECU. The 2G guys, have a little less of a struggle as the 2G’s only require 5 pins total that need to be switched around, though you can certainly still use a patch harness so that way you can quickly go back and forth between the Evo ECU and DSM ECU in the future for whatever reason.

The patch harnesses aren’t that difficult to make but do take a little bit of time. If you are wire savvy, this will be cake. The patch harness requires you to use the internal connector bracket piece out of a DSM ECU. This is commonly snagged from a dead/faulty ECU instead of stealing one out of a perfectly working DSM ECU. The other connectors you will need are for the Evo ECU side. EVO ECU’s use 4 ECU connectors while the 1G ECU only uses 3. The Evo ECU wire connectors (the plugs that plug into the ECU) are the same exact connectors that the turbo 2G uses. So, you can simply find a turbo 2G at a junk yard and clip the connectors off of the wiring harness.

If you decide you do not want to attempt making a patch harness yourself, there are a few people out there that do make them upon request. Carson Jokkel makes them and he can be found easily on Facebook. Most patch harnesses sell for around $150 or less. If you find someone selling one that they made for their own personal use, you can probably buy it for less. I bought mine from a part-out ad on one of the Facebook Groups for $90.


You need to download ECUflash for tuning (free) and EVOscan for logging ($25).



You will need a 1.3u Tactrix cable and OBD2 connectors ( If you are using a 2G, you can use a 2.0 Tactrix cable. You will also need to run the flash cable wire from the Tactrix cable to pin 79 of the Evo ECU. I did not make my own OBD2 port, I bought the Tactrix cable with the OBD2 port, hopefully someone else can chime in on how to make one. Seems pretty easy from everything I have read. You use a black male and female OBD2 connectors. There is a pinout for that as well and I believe there are multiple wires that run to the ECU wiring.

Adding An OBD2 Port In A 1G:

1G DSM’s do not come with an OBD2 port, so you have to wire one into yourself as the other end of the OBD2 plug on the data logging 1.3u cable needs to plug into it. Below is a diagram.

  • Pin 4 of the OBD2 port needs to be wired to ECU pin 26 (Ground).
  • Pin 5 of the OBD2 port needs to be wired to ECU pin 26 (Ground).
  • Pin 7 of the OBD2 port needs to be wired to ECU pin 62 (Diagnostic K-Line).
  • Pin 14 of the OBD2 port needs to be wired to ECU pin 86 (Vehicle Speed Sensor) (not needed).
  • Pin 16 of the OBD2 port needs to be wired to ECU pin 80(Backup +12v Power) .
  • If using a 2G ECU in a 1G, OBD2 pin 1 can be wired to ECU pin 56 (Diagnostic Mode).


You can make a patch harness to use your Evo ECU in your 2G to easily switch back and forth between the Evo ECU and your DSM ECU. But, there are not many wires you need to switch around. So, simply switching some pins around will allow you to run the Evo ECU in your 2G. Above, I posted the diagrams of the 2G ECU pinout as well as the Evo ECU pinout. I will post it again below.

In this diagram, note the colors of a few of the pins. This diagram is at the Evo ECU side. You simply swap the pins with the matching color. Red to red, green to gree, black to black, blue to blue. For example, you will be removing pin 22, removing pin 8, then putting the pin that was in 22 into pin 8. You will then put the pin that was in pin 8 into pin 22. 

In addition, you will be removing some pins completely out of the 2G ECU harness side. The pins you are removing are listed below. There are 4 connectors that plug into the ECU.

First Connector- 22 Pin Connector

Pin 91 (large black) – remove – not used
Pin 87 (yellow w/ red stripe) – remove – not used

Second Connector- 12 Pins

Pin 58 – This pin may already be empty. It is for the tach signal and is not needed when using an Evo ECU.

Third Connector- 16 Pins

Pin 32 (?) – remove – not used
Pin 34 (?) – remove – not used
Pin 42 (?) – remove – not used
Pin 46 (orange w/ black stripe) – remove – not used

Forth Connector- 26 Pins (4 of these are removed, then swapped)

Pin 8 (white w/ red stripe) – remove – used
Pin 16 (red w/ black stripe) – remove – not used
Pin 20 (green w/ orange stripe) – remove – used
Pin 21 (green w/ black stripe) – remove – used
Pin 22 (green) – remove – used

Only one pin needs to be swapped in order for your 2G to fire up and run. That pin is pin 22, which is swapped to pin 8. This pin is for the fuel pump relay. The remaining pins that need to be swapped are for the cooling and AC fans. If you run your cooling fans to a toggle switch, then you won’t need to swap the other pins.


After completing the swap, you may find that your cooling fan(s) don’t turn on as prompted. The primary fan outputs on the Evo ECU are PWM and not compatible with the DSM fan circuits. The Evo fans also have relay/solenoid on each individual fan. This will cause the main radiator fan to go into a fail-safe mode and run all the time once the ignition is ON. 

Radiator Fan Notes

The EVO8 radiator fan is powered by a separate fan control module that expects to receive a pulse-width modulated signal from the main ECU to control fan speed. The DSM ECU does not do this. The DSM ECU only has two simple on/off outputs to control the low and high speed operation of the main radiator fan.

Condenser (A/C) Fan Notes

Condenser fan operation was a little sketchy too because the EVO8 configuration expects the ECU to control both the low and high speed operation of the condenser fan, but the DSM ECU (in factory form) only controls the high speed side of things.

How To Remedy the Fan Issue

One possible way to resolve this issue is by wiring both the AC fan and the normal fan to the AC output and both fans will turn on when cooling is required (its not a bad situation really to have both triggered from the AC output). You can use the fan tables in ecuflash to modify the behavior of the AC fan output to your liking. The only thing that is lost is individual fan control in that simple setup.

The easiest and quickest fix would be to simply wire up the fan(s) of your choosing to a toggle switch. This however can be annoying to have to always remember to flip the switch when you need the fan on. #BecauseRacecar

Another method is to modify the circuit so that one fan turns on to high from the AC LOW output and then both fans turn on to high from the AC HIGH output. This is easy to do with diodes and gives you that more progressive fan behavior seen from the factory.

Finally, you can modify the PWM fan tables to set 100% ground and perhaps have luck triggering the relays for the fan using the 100% ground PWM output from the normal output on the ecu. I have seen a few post where people have got this to work and in theory you can achieve factory like fan control with this. I gave it a quick try without luck, but I didn’t put much of an effort into it because I don’t mind having just two outputs from the ECU to control the fans (AC LOW and AC HIGH).

3G ECU Specific Notes About Fans

The 3G ECU has a few minor differences between itself and the EVO ECU as mentioned further up in the article. The 3G ECU also does not have a pin for the AC relay and is instead controlled by the fan controller. Because of this, your fan(s) will not work at all. Your only realistic option would be to wire the fan(s) to a toggle switch.


You have to use Tephra Mods V7. ROM’s and info is found here

Most people, and so far myself too, have had better luck with the 9653X706 ROM. Note the “X” in the ROM ID number.
If you are using a MAF (any MAF), replace the “X” with the number “0”. This is the ROM you will need to run on your car.
If you are running SD (Speed Density), replace the “X” with the number “1”. This is the ROM you will need to run on your car.


If you are running a MAF, you need to edit the MAF Size values, MAF Scaling values, as well as the MAF Compensation values.

  • If you are running a 1G MAF, you need to enter the 1G MAF values. (currently do not have this information. Most people switch to at least a 2G MAF)
  • If you are running a 2G MAF, you need to enter the values for the 2G MAF. (picture below)
  • If you are running an EVO 8 MAF, you can leave these alone for now.
    I don’t have any input on what you need to do with a GM-MAFT at this time.
  • 3G MAF’s are similar to the Evo MAF, if not the same, so you can leave these values alone if using an EVO or 3G MAF.

2G MAF Values-

  • MAF Size
  • MAF Scaling
  • MAF Compensation

Enter the values shown in the picture below if using a 2G MAF.

esd 2g maf


You will need to adjust your InjectorScaling and InjectorLatency values to accommodate your exact fuel injectors. You can easily find this information by Google’ing your type of injector.


Using an Evo/3G ECU requires you to use the Evo 8 knock sensor. The 1G knock sensors are a completely different sensor as far as how they work and are practically deaf compared to the Evo knock sensor. 2G knock sensors are very similar to an Evo knock sensor and some people have had success using them. The Evo knock sensor plugs right into the factory knock sensor pigtail of both the 1G and 2G wiring harness, insuring a direct bolt on unit with no wiring needed.

Adjustments are required in the Tephra ROM within ECUflash for knock control. For whatever reason, the Evo knock sensor is extremely sensitive with the Evo ECU in a DSM. Below is a screenshot of all the Knock Sensor settings in ECUflash. Edit all of the ones that are different than what you have with your Tephra ROM using the values shown in the picture below.

Knock Settings


In ECUflash with the Tephra v7 ROM(s), Launch Control is achievable by simply activating it in the Tephra Mods option menu. Change the “0” to “1” to enable Launch Maps, like shown in the picture below.

Tephra Options- Enable Launch Maps

You then go to the limiter options and you will see 3 limiters.

  • Speed limiter
  • Rev limiter
  • Stationary rev limiter

The “speed limiter” is the max speed your car can reach before the ECU “shuts off” the car. Which means you just wont be  able to exceed that number (speed), and the car will “shut off”.

The “rev limiter” is how much RPM your engine can reach at any given time.

The “stationary rev limiter” is the maximum RPM value your engine can reach below 5MPH, this is the limiter used for antilag/launch control.

Being able to use the stationary rev limiter function requires modification to your patch harness at pin 43 of the EVO ECU for the Clutch Switch. On an EVO, 12v is sent to the ECU when the clutch pedal is pressed. On a DSM, this pin is grounded when the clutch pedal is pushed in. My patch harness that I bought didn’t have a pin in pin 43. My rev limiter worked, but not the stationary rev limiter. What I did was add the pin to pin 43 and run a wire straight to chassis ground (ran a wire from pin 43 to a bolt on the metal bar under the dash). Ever since then, my stationary rev limiter has worked and I’ve been enjoying antilag.

I’m not too familiar with how the stationary rev limiter works with the clutch pedal, but I would imagine that running pin 43 of the EVO ECU to pin 104 (neutral safety switch) of the DSM wiring harness, would also work. But, I haven’t tested this out. Until I verify, you should simply just run pin 43 of the EVO ECU straight to chassis ground.

Here is a screenshot of what my limiters are set to:



Many of you may have experienced fuel cut in the past with our stock ECU’s. The the factory, our stock ECU’s are set up to “cut” fuel when our load values reach a specified value. A stock-ish DSM will see much lower load values than a built DSM would. When you raise the boost or swap to a turbo that flows more air, along with a couple fuel mods with a SAFC or GM MAFT, you will begin reaching higher load cells.

A load value is simply how much load or “stress” the engine is under. When you start making more boost and thus power, naturally your load value will climb along with it. The EVO or 3G ECU is programmed to generate fuel cut when load reaches a specific value. It is used as a safety feature so that if something goes wrong and you overboost, fuel will be cut. 

To remedy this stock value, you need to go into your Global Fuel Settings tab in your Tephra Mods ROM on ECUflash. You will see the following:

  • Fuel Cut Multiplier
  • Fuel Cut Load x1
  • Fuel Cut Load x2

The picture below illustrates what you need to do to fix this. Open Fuel Cut Multiplier. By default, it is set to run Fuel Cut Load x1, which has much lower load values than Fuel Cut Load x2. You simply change the value to run Fuel Cut Load x2. You can also just set your own load value. I use it as a safety feature as it was designed for. But I am hitting 300 peak load, so it is set to hit fuel cut when the load exceeds 350. In the event that I overboost or over-rev, this will ensure I get fuel cut before anything catastrophic will happen.


Another thing that I have found personally that I needed to modify with the Tephra ROM is the short term fuel trim (STFT) values. My car would start up and idle great (after a couple minutes of warming up) initially, but after I began driving, it wouldn’t idle very well. The idle would keep going up and down and eventually would stall.

I couldn’t figure out what was causing the issue at first, but then I noticed something strange with my STFT readings while logging via EVOscan. My STFT (displayed as “Oxygen Feedback Trim- STFT” in EVOscan) would be around 9% when it idled correctly. But after I drove around and the idle began going up and down, it would read 25%, which is maxed out.

So what I did was change the values in the”ST Fuel Max Trim” table. Originally, 93* and higher on the table was set to 25.6% while the -26 – 68 were 10.2%. I changed the values so that it was 10.2% on the entire table (as shown in the picture below). After making the changes and flashing the ECU, the car has been idling amazing all the time and the adjustments didn’t affect my AFR at WOT or cruise, although my AFR at idle is very high. It’s not a concern to me at all though.

STFT values

From what I have read online, many many people have had similar issues at idle. This may be the fix for most of them. I suggest that you see how your car idles before making this change. It seems like once the engine temperate reaching 93* thus altering the STFT values from 10.2% to 25.6%, the ECU sends more fuel, thus sending more air causing the idle to rise. Once the idle raises, the ECU tries to lower the RPM and then the ECU sends more fuel and/or air back into the engine, raising the idle again. It could just be due to the differences with specific sensors (like the TPS) between the Evo 8 and DSM’s.

It could also just be the lack of me using a ISC as I deleted it along with my FIAV. This is why you should see how your car idles first before making this change. Your DSM may not need this adjustment.


Something that I have recently discovered through some reading online is that a lot of people need to make changes to their Ignition vs. Air Temp table. In fact, most tuners modify this themselves. The reasoning is this table is designed to add or pull timing depending on the air temps that the ECU is registering.

For example, lets say at 5000RPM at load 280, your timing on your ignition map is supposed to see 5*. Well, if the air temp is 122 degrees, your timing will be lowered x amount (or raised) of degrees. In stock form with the Tephra Mods base, your timing will be pulled 2 degrees based on that air temp.

Generally, you want your timing from a log to match your ignition map. The ignition vs air temp table is generally edited to ensure more consistent readings, although this table is designed purely for safety purposes. But it can cause some problems still.

If you take your car to get a dyno tune on a very hot day where you are seeing much higher air temps, your tuner will tune the car for x amount of timing at x amount of RPM. Well, the air temp will vary day to day, week to week, month to month. If your tuner gives the car 5* of timing at 5000RPM, maybe the next day will be colder and your will be seeing 40* lower intake air temps. Now instead of seeing 5* of timing at 5000, maybe now you are seeing 7 or 8 degree.

Below is a screenshot of my personal modified Ignition vs Air Temp table. From what I have read, most tuners zero out all the values in the bottom row (timing axis). But, it isn’t a bad idea to allow the last two columns to have a little bit of timing taken away at the extreme hot air temp areas. If you live in the south and seeing crazy high temperatures on a regular basis, you may want to zero these all out.

I have opted to retain a small portion of the safety feature and allow timing to be pulled at the last two columns, even though the likely hood of my IAT’s seeing 171* and higher is very very slim. Even on a hot summer day, I don’t usually even see 100* in my logs.



Compared to DSMlink or an AEM Standalone, the Evo ECU swap using ECUflash and EVOscan is very cheap. The only other legit route to tune your DSM would be using ECUflash and EVOscan with a 2G blackbox ECU, especially for the 2G guys since there is no need for a patch harness or swapping any pins.

Cost of ECU: The cost of the ECU depends on which ECU you decide to use (Evo or 3G) and how easily you can find one. Maybe you have a buddy with a junk 3G and you can get his old ECU for free. Maybe you can find one at a junkyard and stuff it in your toolbag.

Cost of ECU:

  • 3G ECU- $0-100
  • Evo ECU- $100-200

Cost of Tuning Software:

  • ECUflash- $0 As it is available for download online, legally.
  • EVOscan- $25

Cost of Flashing/Logging Cable:

  • 1.3u Cable- $60-130 Depending if you buy new or used.

Cost of OBD2 Port Connectors (for 1G guys):

  • OBD2 Port Connectors- $0-5 Can be found in nearly any OBD2 equipped car.

Knock Sensor:

  • Evo 8 Knock Sensor- $0-65 These cost only $65 new, currently cheaper than a new 1G knock sensor believe it or not.

I might have $300 max invested into my Evo/3G ECU setup, and I paid $100 alone for the ECU. I could have easily gotten one at a junkyard if I knew then what I know now. You can easily spend a total of $150 or less on your whole setup if you are lucky enough.

Please see our Getting Started With Tephra Mods V7 tech article for more information.