2.3 to 2.5 Lessons Learned 2019 - Mazda3 Forums : The #1 Mazda 3 Forum
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post #1 of 7 (permalink) Old 01-21-2019, 09:36 PM Thread Starter
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2.3 to 2.5 Lessons Learned 2019

When I threw the rod bearing in my 2.3 I knew next to nothing about the car. I had only owned it for a few months and had driven it like a go cart. The mechanic advised me to put oil in it and trade it in on a new car. As it was my daughterís first new car and she loved it, junking/trading it wasnít an option. A little research quickly pointed me to the Ford 2.5 swap as the most economically responsible option. (And who can resist more engine?) Now itís done and the car runs like a dream with its 30K mile Fusion engine. Along the way I had a lot of help so I thought I should probably give back on the lessons I learned that I didnít readily find in the literature. In full disclosure, I used a 2012 Ford engine from a Fusion and put it in a 2004 S sedan. So, here goes.

Lesson 1: Do Your Homework
This has been done so often that there is an abundance of literature out there to help you decide exactly how you want to proceed. There are a bazillion ways to achieve this swap. It will be a lot less impact on your wallet if you know what you are trying to accomplish before you start. Are you going to use the 2.3 intake components, or some of them or none of them. Personally, I wanted reliability and as few teething problems as I could have, so I chose the route of using everything that I could off the 2.3 engine. Did I sacrifice power in the end? Itís hard to believe when driving the car, but possibly. Do the research and decide what you are going to do before hand and you wonít be spending money on things you arenít going to use.
Here are three great sources to get started with.

1. Great starter:

2. YouTube videos by Baxrok2. More detail than you could ever want. Heís hard to listen to at times but has a world of knowledge that heís put on video. Especially helpful is his segment on cam/crank timing.

3. This is a very lengthy post but contains a myriad of different topics that you might want to consider when deciding on your approach.

Lesson 2: Ask for Help
As I said before, this has been done hundreds of times and many of the folks that have done it successfully are on this forum. Most of them are very willing to offer assistance. Just be prepared to provide an accurate description of exactly what your problem is and what youíve already done to solve it.

Lesson 3: Pull From the Top or Bottom?
This seems to be a big debate for many. For me it was easy, I pulled the engine/transmission from the front. Removing the bumper cover, bumper, headlights, radiator and radiator supports took about two hours and added about three on reassembly. I also pulled the hood off in about three minutes. This gives you amazing access to the entire engine compartment and virtually eliminates body damage during the work. (Pic1)

Lesson 4: Donít Make Extra Work.
As you can see in Pic1, I left the AC system intact and just let the components hang while swapping things on the engines. On reassembly, it works fine.

I left as much wiring and plumbing attached to the intake manifold as possible. This created a problem for me which Iíll discuss later, but it helped greatly in matching connectors and plumbing when putting the new engine back in. Everything is close to where it is going to be when you are done and the matching plug/connector is generally the closest one thatís attached to the body. It makes it a lot easier to put things back the way they came from the factory. (Pic2)

Lesson 5: You Have to Use the 2.3 Cam Chain Cover.
The Ford timing components are not compatible with the Mazda engine management system. That means using the 2.3 Crank Position Sensor which means using the 2.3 Crank Pulley and Cam Chain Cover. I suppose you could make modifications to the Ford cover and use the Mazda components but why go through the headache? The 2.3 cover also has mounting points for the alternator and idler pulley that the Ford does not.

Lesson 6. You Have to Use the 2.3 Oil Pan.
The AC compressor is mounted to the oil pan on the Mazda3. Unless you want to modify the carís AC system to move the compressor to the Fordís location, you will need the 2.3 oil pan. This creates two more issues. First youíll have two dipsticks. I chose to use the Ford dipstick for no logical reason. I just liked it better. To block off the Mazda dipstick port on the oil pan, I got a Ĺ inch hitch pin and used a Ĺ inch drill to spin it and cut an o-ring groove in it at the same distance down as the old dipstick tube. (Pic3) I then put it in place of the dipstick tube and have had no leaks whatsoever in 500 miles of driving. (Pic4)

This left me with a second issue. I needed to calibrate the Ford dipstick to the 2.3 oil pan. Before plugging the dipstick hole, I filled the engine to full on the 2.3 dipstick then marked that level on the 2.5 dipstick with a small triangular file. (pic5)

Lesson 7. Engine stands are great, two engine stands are even greater.
When you are moving tons of little parts from one engine onto another, it makes things much easier if they are both off the ground, in the same position and side by side. I owned one before I started and then found a second with an engine puller for $100 at an on-line surplus auction here in Phoenix. If I decide to, they will fetch that much on Craigslist and Iíll be out nothing. (Pic6)

Lesson 8. Youíre likely going to have to undo and redo something(s) at least once. Adapt and improvise.
When I got the 2.5 in and started, it wouldnít idle with the MAF plugged in. In trying to figure it out, I retimed the cams, changed the MAF and eventually had to remove the intake manifold. In most cases an OBDII reader is an indispensable tool. In my case it was as well although the readings confused me and everyone else that saw them. You can get a cheap reader for under $10 and an app for under $5. Save yourself tons of headache and get one. The more expensive ones are tools that you will be able to use for years.

When resetting the cam timing in the car, getting to the cam gear bolt is an issue because it sits close to and behind the timing chain cover. I went to the parts store and bought a good (not great) quality 21mm box end wrench. I used a flap wheel on a side grinder to create a very thin 21mm box end that I could slip onto the cam gear bolt head without removing the cam cover. I took material of both faces because the teeth on the box end are beveled and I wanted as much tooth on the bolt as possible. (Pic7)

When removing the intake manifold I was told that I needed to pull the starter to get to that one bolt right under the intake runners in the middle of the manifold. When itís out of the car (or when the radiator is removed you just need a long extension and a 10mm socket. With the radiator and engine in the car you need another approach. Rather than removing the starter and working from below, I removed the serpentine idler and exposed the right side of the manifold. (Pic8)

This let me slip (barely) my left hand behind the manifold and stick a long socket and extension out the center hole and join them to a ratchet and short extension. (Pic9) Then it was one of those braille exercises to guide everything onto the bolt head.

Lesson 9. When it quacks like a duck and it walks like a duck and it looks like a duck, it's probably a duck.
As I mentioned earlier, when I first got the 2.5 started it wouldnít idle at all with the MAF sensor plugged in. The first indications from my OBDII reader showed real high fuel trims which means that it is running too lean. I sprayed at least two cans of starting fluid on the intake manifold and hoses looking for a vacuum leak. Nothing. Then I pulled and cleaned all of the injectors, then changed all of the injectors, still nothing. Then I checked the fuel pressure (55lbs at idle) and all ancillary circuits. All good. I finally went for help. I took it in to Phil at Litchfield Automotive here in the west valley of Phoenix. He checked it over (for free) and said I had a vacuum leak somewhere in the underside of the intake manifold. I didn't discover it because I was using ether which evaporated before reaching the underside of the manifold.

I wound up pulling the intake manifold (and cleaning a very dirty throttle body) to find a plastic clip immediately below the #3 intake port had been bent up between the adapter plate and the head. (Pic10) In trying to get the adapter in place and handling the manifold with all of its attached wiring and plumbing, I had shoved everything straight into position when the adapter plate needs to be dropped down into position. Pulling the clip back down, out of the way, and reinstalling the intake manifold solved my problem completely. Baxrok2 had a very similar story involving his cam timing. The moral of the story is that if you have symptoms that point to a particular problem it is probably that problem no matter how much you think you have eliminated the possibility. Look for horses before looking for zebras.

For all the work and frustration involved in this project, I would do it again because it is fun and the result is a great driving car. I don't know about horsepower increases in this configuration, but the torque improvement is amazing. I probably shift 20% less with this new engine. The car feels great!
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Last edited by fireguy132; 01-21-2019 at 09:45 PM. Reason: correction
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post #2 of 7 (permalink) Old 02-19-2019, 09:09 PM
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Thanks for the lessons learned! I am currently in the middle of this same project. I'm using a 2015 Fusion engine with 16k for the donor. I have read a lot on this forum which has really helped with process!
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post #3 of 7 (permalink) Old 03-12-2019, 01:42 AM
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Lesson 10.
Use the Mazda spark plugs!

Engine crank, no start.
I re-verified cam, crank timing with the proper tools today. All good. Good spark and good fuel pressure.

In my last desparate act, I swapped out the FORD spark plugs for the original MAZDA plugs. I was thinking that since it was a Ford engine , that I should use the Ford spark plugs. Wrong! Apparently the Mazda ignition system did not like that! Started right up! I feel like a dumbass for making that mistake, but I hope someone else will read this and know better!

The fuel pump was the original problem on this car. I did not troubleshoot it myself after I bought it. I just went by the compression readings taken by some shop. I didn't find this out (bad fuel pump) until after the engine swap was complete. Fuel pump fuse blown. Replaced the fuel pump and it worked for about a day, so They are sending me a new fuel pump.

I read rickkari's entire thread regarding the swap with newer engines, as well as this thread and about 10 others. It was great and a huge help. The only difference between mine and his, was that I did not have to modify the valve cover to fit the VVT solenoid rubber bushing. Mine was a straight swap. I am using the 2.3L intake with the adapter plate. The IMRC plunger got stuck on the intake adapter plate. A little filing took care of that. I'll get to actually start it up and run it this weekend as the fuel pump will arrive before then.

Thanks again everyone for your responses and collective experience! These forums are priceless!
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post #4 of 7 (permalink) Old 04-26-2019, 10:04 PM Thread Starter
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Time for an update.

It's been 6,000 miles since the swap was completed. For the first thousand or so, I kept getting a lean at idle code, occasionally with a low coolant temp code. Watching the fuel trims and O2 sensor readings, it kept looking like a hiccup from the ECM so I cleared them and ignored them. After the first thousand miles, the frequency tapered off until I don't get them anymore. I guess it was the ECM "learning." Other than that, I've had no issues.

Driving this thing is a hoot! It has so much torque that you almost don't need to shift (it's a manual), but when you do, it goes like stink. This car is now so easy to drive and so much fun that I would do this swap again in an instant. I probably spent more time than was absolutely necessary, but it doesn't matter, I'd do it again.

For those thinking about it, DO IT! Take your time and research any issues you come up against and the end product will be well worth the effort.

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post #5 of 7 (permalink) Old 04-26-2019, 10:16 PM Thread Starter
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Billistic4, thanks for the addition. I used new plugs so had no issues, but they were the ones listed for the Mazda.
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post #6 of 7 (permalink) Old 01-22-2020, 09:06 PM Thread Starter
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Time for another update. I've got 17000 miles on the swap at this point and I have had zero problems. It continues to run well (real well!) and the car is a blast. I live in the boonies in Arizona and the majority of my miles are on I10 with tons of semi trucks. This swap makes moving about in traffic no sweat. Going 80 and need more speed? Just step on the gas, no downshift necessary. It pulls strongly all the way through 100. I love a car with power!

Just recently it is occasionally throwing P2178 codes when it's cold. I'm thinking I am due for new O2 sensors. The car has 160K and those are the original. New ones coming soon.

Other than that minor annoyance, life with the swapped 3 is good. DO IT!!!
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post #7 of 7 (permalink) Old 01-23-2020, 09:14 PM
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Thanks for the update. It's always good when people report the status of mods or other enhancements.

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