Really interesting stuff. I wonder if you would pass emissions with all the changes. When I bought my Montero I knew it was underpowered (3.0L) but the truck had so many other good features that I bought it anyway. The purchase has done well for me as I have had zero problems with this SUV other than normal wear and tear. Your tinkering has paid off as you seem to be accomplishing your goal as evidenced by the uphill runs. From 3rd and 50mph to 4th and 55mph is impressive for the dollar input. The trade offs, aren't there always, seem to be acceptable for you. I look forward to your next post.

 

Well, all I've really done so far, other than set the cam back to its stock position, is the IAT mod - but there's a lot more to come!

As for the emissions question, particularly in regards to mods I'm doing, here is my logic on what I expect (hope?) to find....

1) The IAT mod shouldn't affect emmissions testing since before going to the testing station I can simply turn the dial to its zero ohms setting and the IAT signal goes back to stock.

2) The cam gear mod shouldn't have a negative inpact on emmissions either. It recently passed emissions with flying colors - even though the cam was advanced a full tooth - making it 7.5 degrees too fast. From that I conclude that an adjustable cam gear and 3-5 degrees cam advance isn't going to hurt anything in terms of emmissions.

3) The low restriction air filter is going to allow it to draw in a greater volume of air more easily. However, the air will still all pass through the Mass Air Flow sensor (MAF), which is what tells the ECU how to pulse the fuel injectors to deliver the right amount of fuel to mix with the air. So, the air fuel ratio, and therefore the emissions, shouldn't be affected by that either.

4) Swapping the throttle body may present a little more of a challenge - but then again it may not. If I use the original MAF, then the effect should be about the same as the air filter - little or nothing emmissions-wise. However, the smaller original MAF won't net me as much potential airflow benefits as the larger one from the 2.4 liter. At that point it would be the most restrictive bottleneck in the intake system.

5) Swapping the MAF is even a little more likely to present some challenges - but again, it may not create any issues either. It all depends on what approach Mitsubishi took. This is where I've had to do a fair amount of research. I have done a LOT of pouring over the MPI and engine bay wiring diagrams for my 1.8 liter and for the 2.4 liter. In all critical respects, the two are identical. Wiring colors, connectors, pinouts, and the connections to the temp sensors, ECU, TPS, MAF, IAT and IAC motor are all the same. The testing procedures for the individual components, and the test values for them, are all the same as well - at least for the ones that the manual lists a testing procedure. In fact, several of the procedures are listed together as being "for the 1.8 and 24. liter engines".

The big difference between the two is that, due to its displacement, the 2.4 liter needs to suck in a larger volume of air every revolution than what the 1.8 needs - 1/3 more to be exact. The 1/3 larger volume of air has to mix with 1/3 more fuel to maintain the correct air/fuel ratio. There are several possible ways that Mitsubishi could have designed the system to deliver this increased fuel. This is where some serious thought and logical deduction comes into play. The alternatives as I see it (listed in the LEAST-likely-case-first order) are

A) Make the two MAFs pin compatible, program the ECUs the same, and use the same fuel injectors, but make the MAF output signals (for a given airflow volume) different - to make the ECU pump more fuel through the injectors.

B) Make the MAF output signals (for a given air flow volume), and the fuel injectors the same, but program the ECU to control the injectors differently so that they push more fuel.

C) Make the MAF output signals (for a given air flow volume) and the ECU programming the same, but use larger, more free - flowing, fuel injectors.

D) Make everything the same except the diameter of the MAF. I think (and hope) that this may be the case - for a few different reasons.

First, the system uses a MASS Air Flow (MAF) sensor to measure airflow. This makes me think that the output of the MAF is proportional to the absolute quantity of air that passes through it - not the speed or pressure of the airstream. The larger MAF can have the same output signal as the smaller one when flowing the same quantity of air - if it is truly measuring the total amount of air sucked into the engine. The air just has to move more quickly through the smaller diameter MAF to get the same volume per unit of time as the larger one, but they should both give the same output because the same amount of air has passed through them both - it just moved faster through the smaller one.

As long as the fuel injectors have sufficient capacity, then an ECU with the same programming controlling the same fuel injectors should maintain the same air fuel ratio with two different sized MAFs flowing the same volume of air and giving the same output. The benefit of the larger MAF would come from the fact that it requires less vacuum for the engine to suck an equal quantity of air through it. Creating less vacuum means less power wasted on sucking the air through the intake - which equals more power available at the wheels. Kind of like the difference between sucking a drink through a skinny little coffee straw versus a regular straw. You can get the same volume at the same rate, you just don't have to suck as hard on the regular straw.

Second, since the TPS and IAT test procedures and values are the same for both of them, and the IAT is incorporated into both of the MAFs, it would make sense that the rest of the MAF electronics would be the same. Making the two of them different would just create a needless increase in R&D, tooling, and manufacturing costs. Same is true for the TPS.

Third, the same idea applies to the ECU programming. Creating two different fuel and timing curve maps would mean a fair amount in R&D costs, an expense that could just as easily be avoided by making them the same and changing something else if necessary.

Basically, the most economical thing for Mitsubishi to do from a manufacturing standpoint would be to make everything identical if possible. If that weren't possible, then the most likely reason would be that the injectors for the 1.8 liter couldn't push enough fuel to mix at the right ratio with the increased air volume of the 2.4. In that case the simplest solution would be to upsize the injectors and be done with it.

So, based on my research, my understanding of how the fuel injection system works, and what I know about manufacturing economics, I'm hoping that my deductions are correct and swapping to the larger throttle body and MAF won't have any major negative effects on the emmissions either. I expect that, at worst, it might create a lean condition that can be easily corrected by modifying the MAF signal, or swapping the fuel injectors. Kind of an application of the Occham's Razor principle. The simplest explanation (or solution) is the most likely one for Mitusbishi to choose.

Sorry this ended up being so long, but that's a problem I'm known to have - making long-winded explanations. At least I know that if anyone read all of this then they really MUST be interested....

 

More and more this "experiment" is sounding like a project car.

 

Well since "tinkering" (as PC called it) with cars is one of my hobbies, I guess (by your definition) you could say just about every rig I've ever owned was a project car, FireDoc. I just get a kick out of seeing what I can do to make a rig better. Especially if I can figure out how to do it for cheap

BTW, FWIW, once I do the air filter and throttle body mods (even if I replace the MAF), and then fab my own adjustable cam gear, I'll still have spent less than $160 total. Unless I have to replace the fuel injectors to make the throttle body/MAF mod work the way I want it to. That would add some to the cost.

I only spent $1800 for the car around 3 years ago, and just put another $900 into it for the tranny, the clutch set, and the clutch hydraulics rebuild kits. $2700 total investment. In the meantime I've gotten a couple of years use out of it and put 25k miles on it, so I figure I'm still WAY ahead of the game with this rig. KBB says it's retail is $4,600 and wholesale is $3,000 for one that is in "good" shape. I have less than that into it, and it nearly fits the definition of what they would consider "excellent" shape.

So, if I spend a couple of hundred on playing around with it, then its no big loss. I should be able to recoup it if I ever sell it. If I don't, then OH WELL, at least I had some fun with it

 

I see nothing wrong with your goals. I, however, Will spend $ whatever the cost if it is what I have to do to get the best results I can with my ability level. I guess that is also why I have a hard time getting rid of ANYTHING I modify, too much sentimental value. A victim of my own device!

 

I appreciate what you're saying. I have stuff that I've fabricated, worn out, taken off, and abandoned YEARS ago - for vehicles I don't even own anymore - still lying around!

In my case I don't feel that I lack much in ability, just specific knowledge. I enjoy the challenge of making the largest improvements possible for the least amount of cash out-of-pocket. Doing the research and figuring out ways to do or make the spendy mods myself - cheaply - is a big part of the appeal.

For example, I have a Jeep Cherokee that I've been working on for about a year now, making it steadily more and more off road capable. Last time I updated my modifications list I had made improvements/upgrades to it that would retail for close to $5,000 if I just bought the parts ready-made (not counting what it would cost to have them installed). By buying the few items I couldn't build myself second-hand, and then designing and building the rest of parts myself, I was able to do all of the modifications for under $2,000. The net result is that I have less than $4,000 total invested in it, and it is probably one of the most modified and capable $4,000 Jeep Cherokees on the planet!

So, that's where I'm "coming from". I could probably afford to buy the most expensive mods available, and even pay to have someone install them for me if I really wanted to invest that kind of money. But what would be the fun in that? Doing more with less is not only more interesting, it just makes more sense to me financially.

 

"Justification for a higher education"

 

Yeah, kind of like another fabricator/tinkerer/Jeepaholic I know is fond of saying......

"Building anything just requires the right combination of brains and materials. The more brains you use, the less materials you need!"

But with me, you can substitute the word "money" for the word "materials"......

 

When I got home last night the cone filter and MAF adapter were sitting there waiting for me.
OH BOY, OH BOY!

I Installed it all today. I disconnected the battery while I did the install to reset the ECU for good measure. It was a pretty simple install. I started by pulling out the MAF and the tube between it and the throttle body. Then I removed the old stock airbox and the frame that supports it. I had to fab a support bracket to bolt between the MAF and the fenderwell to give the MAF & filter some support and hold them in place - can't have 'em just flopping around under the hood. After it was all installed I took it for a test drive to see if I could tell the difference.......

MAN what an IMPROVEMENT! MUCH quicker throttle response, revs up much faster, revs higher in every gear, more power - at both low AND high RPMs, better acceleration. It pulls stronger to redline and actually seems to be reaching a higher top speed in each gear. In second it will run all the way up to 50 mph, and in third it will pull hard all the way up to 70! Seriously, this intake filter REALLY woke this little motor up!

AND IT SOUNDS REALLY COOL TOO! At anything below 1/2 throttle the increase in intake noise is hardly even noticeable. BUT at wide open throttle (WOT) the intake noise gets significantly louder than it used to be, though not obtrusively so. Just a really nice growly sound that quickly builds to a full snarl. I'd say that at WOT you can hear about twice as much intake sound in the cabin as what you could hear with the stock intake, but the sound has a much lower, meaner quality to it. Needless to say I LIKE IT!

Made a couple of high-speed WOT passes at my favorite hill to confirm what the old "butt dyno" was telling me. At the start of the steepest part of the hill I was in 4th gear and was up to 75-78 mph - versus about 70-72 mph before. I topped the hill at 62 mph (!) - compared to 55 mph before installing the filter - and 50 mph originally! A 12 mph improvement over the original 100% stock setup. If letting it breathe by installing a low restriction filter makes this much difference, I can't WAIT to see what the bigger throttle body and MAF will do for it!

Next thing you know I'm going to be challenging hopped up Civics to stoplight drag races Wouldn't that blow 'em away - gettin' whupped by a MINI-VAN?

 

Spent a couple of hours giving it a good cleaning today. Probably the first real "bath" its had in about 2 years. I figured that since it is running good and has been pressed back into DD duty, it was due for a good scrubbing down. Afterwards it looked so good I decided to take a couple of pictures! As far as exterior/appearance mods, the only things I've done are the wheels, some slightly wider tires (with a lower profile to maintain stock overall diameter) and the front "chin spoiler" - which actually came off an old Ford Ranger I used to own, but just happened to fit almost perfectly with virtually no modifications

I don't have too much planned in terms of appearance mods either. Probably tint the windows, repaint some of the black trim, and maybe add the rear "wing" from a late 80's / early 90's civic hatchback across the top of the rear hatch - if I can find one cheap enough. Might fabricate a set of side skirts out of plastic too - just to give it the aero look. I need to find a set of factory form-fitting front mudflaps to mount in front of the rear wheelwells before I can do that though. I figure the skirts can attach to the molded mud flaps front and back that way and it will look almost factory - but cost next to nothing.

Anyway, here's what it looks like right now.....

[IMG]local://upfiles/3817/8968439E5A2D4B88A778EA6C51089F3C.jpg[/IMG]

[IMG]local://upfiles/3817/4E627E9671AA49B680C48149FCDCF892.jpg[/IMG]