3500 engine swapped into 93 3000gt, came with both ECU modules, but mechanic never put these in,

Asked by Sep 20, 2014 at 09:41 PM about the 1993 Mitsubishi 3000GT 2 Dr STD Hatchback

Question type: Car Customization

Guy sold us car with bad engine, then changed it out for a 3500 engine, he said he
was told, "no need to change ECU's" however it will not pass inspection cos emissions
are way off.My immediate question was, " surely an engine half a litre bigger will need
different tuning parameters". The 2 units that came with the 3500 engine have different
wiring ports, so will not just switch over. Any thoughts ? The car also cuts out on

11 Answers


Is there any way you can check the emission system like are the 02 sensors bad or the catalytic converter without the ECU?

Thanks, but you seem to be bypassing the main question, how can an engine operate correctly with the wrong engine management system, and how does one work around this. Also new Cat and 02 sensor, of which there is only 1 on the 3000 GT.


Oh man. I don't know what you can do if the wiring hardness are different.


I would try to find out what make, year, and model your current engine came out of and try to find a used ECU and go from there. Remeber they used this motor in several cars ( Dodge Stealth, 3000GT, Diamante ) these are just a few I know of. Good Luck


Also if you look at the right side of the screen you will see the top 3 Mitsubishi experts, you can always message them and see if they have a better answer.

Again, the 3500 engine came with both modules, they are not compatible with the 93 harness plugs, the question is, can the existing ECU's be re- programmed to accomodate the 3500 engine ?


Best ask the local Mitsubishi dealer. They are going to be the one that you will have reflash it anyway.


Sorry reecepiece I been out of town. Don't have an answer for reprogramming the gt ecu to operate the 3500 engine. Never tackled that swap myself. I suggest to find a donor vehicle with same 3500 engine and get the harness to use on your car. This would be the easiest fix in my opinion. Also the 3500 only creates 201 hp where as your stock engine was 222 hp. But if you never was able to drive car with original engine you will not feel what you are missing.


http://www.milzymotorsports.com/3500-swap/ -- you might find some useful info here. The 3500 is normally a replacement for the 3100 and 3400 engines of Chevy vehicles. This site covers most issues these owners encounter during a swap.


http://www.3si.org/forum/f35/my-6g74-3-5l-swap-webpage- 240131/index3.html -- here is a 3500 gt swap. It's long and drawn out. Not sure there is any useful info there but maybe the author who did the swap can help you out. Sorry I could not be more helpful.

I must be missing something here, in what country are we talking about swapping Mitsubishi 3500 engines into Chevy's ? your links make no mention of the Mitsubishi engine, and the info is totally irrelevant to the 3000gt. An easy fix would be to change out the wiring harness !!!! REALLY ? that's an easy fix ???

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