Talk me out of (or into) the Mopar MPI

[Techlight]

I know I know...there are so many FI threads on the forums and this topic has been over done...I'm really just ranting so I can hear other people respond...

So with my tax return coming, Ive been kicking around buying the EFI for the CJ and can't really decide since they're so damn pricey. I know I want the damn thing, but I could make a lot of other purchases as well. I've considered the Howell kit but it seems kind of half way and I'm pretty sure I'd spend another 4-600 bucks on upgraded ignition and other parts as I go along so in my head I price it at about 2k. Oddly enough, as I read the instructions for both kits the MPI seemed easier to install than the Howell...go figure.

I found the full MPI kit with vibration damper for 2553 (without shipping). I have read and read about the 2 kits (i'm in CA and need smog stickers) and I'm really on the fence. 2600 bucks could buy me quite a few other mods that I probably need sooner, but I keep wondering when I'll have 3k to drop on the Jeep again...probably not soon.

I'm kicking around dumping my honda civic and using the CJ as a daily driver since I don't commute anymore. I'd like a bit better gas mileage and even though the honda has a newer motor in it I feel like I keep dumping money into it because it's my daily, and why not start putting that money into my Jeep. Although I might baby the jeep more if it's my only car...as it is now I'm not as concerned if it breaks and has to sit in the drive.

Lol, this post reads like a diary entry...l should be more clear.

In my head I feel like it's a choice between the howell, and upgraded ignition, and maybe some new tires, and a sending unit for the gas gauge (haha). Or the MPI only. The motor only has 5k miles on it so now's probably the time to choose one of them and move on lol.

My biggest concerns are mpg and reliability going forward so I really can't decide.

The other question I have is I've heard that the MPI's don't like modified engines. Mine isn't that modified...but I was wondering about that mild cam I put in the new motor.

Any advice or thoughts? My jeep needs a ton of other things, and like all of us I can spend 2600 bucks in my head pretty quickly without even thinking too hard about it.

 

[Bent]

My questions/concerns about the MPI
1. The computer is basically programmed for a 4.0? An over square, short stroke engine can't handle as much timing advance coming off idle. The AMC 258 i6 / 4.2l really snaps to attention with a loosely adjusted vacuum advance. I wonder if the 4.0 computer will advance the timing as much as the AMC 258 i6 / 4.2l likes.
2. The MPI and TBI kits use a CPI on the balancer and not on the flywheel like the 4.0. This places a CRITICAL sensor down in the mud and water.

The advantage of the TBI kit is you can keep your distributor and can tune the spark advance to provide more than the computer might allow. The advantage of the MPI is precise fuel control at low rpm. Also, you could swap in a 4.0 flywheel and modify your bellhousing for a CPI.

 

[hole]

I cant recommend the Mopar enough If you want or need a little more out of it, just ask the guys that put it together at Hesco. Awesome bunch of guys there

 

[hole]

You can also save a bunch and get all you need off of a 91-96 Cherokee at the bone yard, then just buy the balancer and CPS pickup from Hesco. There's a few folks on here who have gone that route and seem to be happy with the results ( and extra $ in their pockets too)

 

[ThisGuyUKnow]

Make it yourself and save 2 thousand dollars. And mpi is by far superior to tbi hands down.

 

[Neuner]

If I were you, I'd first adjust my w-4 exemptions so that the corrupt government wasn't being used as a bank account and holding that much of my money for so long. Could have made an extra 5-10% in that year investing it correctly instead.

 

[Torxhead]

The way I see it is if you have the time and money go for the Mopar kit, the Howell kit has been good for me for around 12 years or so, but I think might be worth twice the money in the long run. Either one will be way better than the carb system that you have. Stalling out on a long steep hill with a carb is no fun, plus the increased power and gas mileage makes it well worth it.

 

[Techlight]

Thanks for the input to you all. I do appreciate it.

I do need to fix my W4 lol...and I do think I might venture to build one from scrap, but I'm in Cali so I need that CARB sticker which is why I was considering only the two kits.

I'm still a bit undecided, haven't purchased yet either way, but only because of the dollar factor. We'll see how it shapes up in the end. Thanks ...

 

[hole]

Stop in and see your local area smog referee station, ask about the requirements, doing it from scratch, etc.

 

[jdarg]

I would junkyard TBI it and upgrade the computer so you can flash from a laptop. Infinitely tunable to your application from there. If you want to avoid the learning curve, I would go Howell.

TBI doesn't use a crank sensor.

Any of the normal advantages of MPFI vs. TBI are completely lost on the AMC 258 i6 / 4.2l ...IMHO. Its an inefficient head design and low RPM application. TBI is just better suited for older design motors IMHO. You can also keep the motor looking essentially the same and not have to run a XJ/YJ airbox, etc.

The MPFI is just too "closed" of a design at this point...a "black box" that very few people understand how to tune and modify. It is more sensitive to sensors failing than TBI, not that any of the sensors themselves are necessarily more unreliable (the crank sensors don't have the best longevity though.) IIRC the MPFI kits have a nice warranty though, but I might be wrong on that.

TBI is very well understood and has been for years. All of the code in the computer has been figure out...like 20 years ago...and people have been refining it since. It is by far the easiest platform to learn about fuel injection & tuning...and get good results yourself. Help abounds on the interweb. You can be burning chips for about $50, or flashing new tunes from your laptop while you drive for a couple hundred. I can't recommend DynamicEFI's upgrades enough.

 

[Lumpy Grits]

You had better talk this over with your SMOG test guys to learn what all is needed, along with what must and can't be used.
Are you going to do this install yourownself? I ask because, it will be a couple of buckets of $$$ to get it done and pass SMOG
Did you get my last PM about a possible fix for your tranny/t'case leaks?
Me-I'll keep run'n my carb and smile
LG

 

[Techlight]

You had better talk this over with your SMOG test guys to learn what all is needed, along with what must and can't be used.
Are you going to do this install yourownself? I ask because, it will be a couple of buckets of $$$ to get it done and pass SMOG
Did you get my last PM about a possible fix for your tranny/t'case leaks?
Me-I'll keep run'n my carb and smile
LG

Hey LG...

Yeah, I wouldn't even attempt a junkyard version. But that's only because we can't even change an air intake assembly in CA without a CARB sticker and I don't need the headache arguing with the referees. I like the kit either way and would go that route because I doubt my skills to build stuff. Which is kinda funny considering I'll change the motor, clutch, tranny/transfer, bushings all the way around etc. on my own but won't do other stuff I'm afraid to tackle lol. Need a motor swap, sure lol. Need your carb adjusted...uh, no. I pay a guy to do that.

I ended up doing some other stuff with the cash instead of the EFI...figured tires were more important. Added a few extras (center console/cb/lights) for fun and I'm good for now.

I did get your PM...I'm just slow in responding. I took your advice on the tranny leak and we'll see how that goes. Next on the list is checking/hunting down whether I'm running rich or not on the carb as well as checking my front end for steering issues. If your up for it in a weekend or two I may call you to see if I can come over and have you walk me through the front end check. I need to repack the bearings but I'd like to check play in the steering shaft and tie rod ends since I"m about to install a 0 mile power steering gear I picked up since mine is leaking.

 

[Lumpy Grits]

PM sent-I'll be at the Chino Air Show this weekend and the following weekend is Mothers Day.
Anytime in between or after MD is good.
LG

 

[Sasquach]

If you go with the MPI do the 4.0 head at the same time, they compliment each other. I have smogged mine 3 times now and it seams they are trying to find something to fail me on yet it passes and they never ask about the head and later tube exhaust.