2005 Mazda3 2.3L to 2.0L Engine swap questions

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david05

Member
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Mazda 3 GT
Just bought a 2005 GT with some engine problems and high km and I want to put the 2.0 engine and trans in the car. I can get them both for $500 with 130K on them so that's why I want to go that route. Since this is my first Mazda I don't know anything about what is interchangeable so any advise as to what parts I would need would be appreciated. Also the donor car is an 06. Please note that I know this is a down-grade, will require a lot of work and that It would be easier to buy a gs, but funds are short.
 
I would think that getting the computer and wiring harness from the donor car will be a good idea.
 
I am getting a full car to use for parts and will post what I find in case anyone else needs the info or wants to go to the 2.3L
 

I don't absolutely know for sure. I don't know anyone who has done this before, but it should be a relatively simple swap. Physically everything is the same, and as long as you use the PCM from the donor car everything should work as it did before.
My only concern would be an engine/trans w/130k on them already. That's 81,000 miles to many of us.
 
Engine and trans are in and mostly hooked up, the only major difference I noticed on the wiring harness was that the 2.3 had two wires for the coils and the 2.0 had three going to each. The throttle body on the 2.3 has a larger bore and the plugs on both 2.0 and 2.3 throttle bodies are the same. I actually ran the 2.0 throttle body on the 2.3 when I was trying to get the car running properly. The new engine and trans actually have 106 thousand km on them compared to the 256 thousand km on the old. Also I couldn't get a used engine for less than 2 grand and at that point the budget would be blown so that was the reason for using the 2.0 and doing the swap. The parts car cost $600 and was rolled and stripped of body components and rear sub frame when I got it. I will be trying to finish the swap this weekend, only have a few things left to get done. The old engine had good compression still but smoked really bad and had a bad maff sensor, barometric pressure sensor, throttle body servo and coil. After fixing those things the engine still ran like crap so the swap was started on Monday.
 
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Sounds like you are making good progress. Keep it up and let us know how it all works out. Best of luck.
 
Rain is slowing me down since this has all been done outside, I will take some picks of the throttle bodies and harness but otherwise go look under your hood cause it all looks stock on mine.
 
The swap has hit a snag, everything is in and hooked up but for some reason the car will not crank. I have tried going back to the 2.3 pcu but that didn't help, and I also put the 2.0 cars gauge cluster in to see if that would make a difference which it didn't. The two engine harnesses have the same wires running to the same places on the plug that connect to the chassis harness. I plan on asking a dealership if they know what it could be but if someone has any input it would be appreciated.
 
If it won't crank at all (starter does not turn engine over) check all battery connections and especially engine and chassis grounds. Check fuses and stuff too. start with the simple things and work from there.
 
I tried a jumper wire with a switch to the solenoid and that made it crank and also replaced the wire plug for the solenoid because I read they can get corroded, but that didn't fix it. I'm gonna check the clutch switch next because the car would start without that pressed down before I swapped engines. Grounds are good I checked the voltage at the starter.

EDIT
The car is now running I had to reprogram the keys and use the gauge cluster from the parts car. So for those that swap either engine into either car you MUST make sure that the PCU, gauge cluster, and keys are programmed the same.
 
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Periodic miss fire on cylinder one, may just be the spark plug cause it only happens when I get on the throttle to hard. But yes it is nice to be able to drive it.
 
So I would like to know if anyone knows the cc's of the 2.0 and 2.3 injectors and if they are the same. I'm thinking an injector may be the source of the problem and would like to use the parts I have.
 
The spark plugs were the original ones with 107k on them, one was badly carbon tracked so I replaced them and found that the coil Is the problem, but it may just be the boot.
 
david05 said:
So I would like to know if anyone knows the cc's of the 2.0 and 2.3 injectors and if they are the same. I'm thinking an injector may be the source of the problem and would like to use the parts I have.
Click to expand...

Does anyone have the answer to this question?
 
Hi all, just subscribed, I just bough a 2004 Mazda 3 Sport 2.3L Manual, the engine got 282k km and probably just spun a spme cank bearing, it was consuming oil and the previous owner waited 2 liter and the oil pump miss some oil in a quick turn (The car drive but tick like a time bomb on idle and more on small rev just to move it.) I want to do the 2.0L swap in the next month.

As I read on another forum, no need to reprogram the key if i keep the 2.3L ECU, cluster and oem keys already in the car. So i can just swap to the 2.0 Engine and like you pointed keep the 2.3 coilpacks and TB ?

also I got a better deal on a 06-07-08 2.0 Engine, same price as the 04-05 2.0 Engine but the donor car have 50k km instead of 104k km.... According to wikipedia it's the same engine, but maybe some sensors and connector placement are different ?

EDIT: just read 04-05 have no VVT, but 2.3L have it so still unsure if i can get the 06-09 2.0L and be direct swap with the 2.3L ECU etc....

Also heard of hamonic balancer been different on 2.0L AT and Manual and this can't be swapped, is it true and will an AT engine suffer been transfered to the flyheel on the Manual 5 speed 2.3L tranny ?

Last question is does the AC compresssor of the 2.3L (already in the car) can be transfered to the 2.0 engine without disconnecting the AC line during the swap or do I absolutely need the 2.0 AC compressor...

also it's the same 5 speed transmission for the 2.0 and 2.3L ?

Thanks in advance, my first Mazda, I usually work on Toyota (Previa, Supra MKIV, MR2 and Echo) !
 
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