spistols

OK, new to the Cherokee scene. Have a '93 2.5L manual trans 4x4 Cherokee. Has now about 183K. Body is excellent with no rust, AC cranks cold air out, and is good for off roading, so that is why I am keeping it.

However, the 2.5L is a dog when it comes to power. Did a tune-up: cap, rotor plugs, etc., and runs slightly better but still a dog. 75mph on the highway takes time to get up to.

Read that swapping to a 4.0 of the same year may be a chore or rather, more of a headache.

What is a good, simple, but noticeably effective mod to the motor to give me at least enough power to stop considering a complete motor change out?

Would new fuel injectors be an answer- and if so, exactly what type would I need?

thegee

Hi, is your Cherokee stock or already lifted ? Are you running stock tires and wheels ?

Some minor improvements, a cold air intake and a catback exhaust. Don't expect a gain of 20 horse poser.

spistols

Thanks. It is completely stock with the exception of 225/70R16 tires/rims from a later model Cherokee.

4BangerDanger

Hey brother! I also have a '93 2.5L 5-speed. I'll drive mine forever; they're fun little Jeeps.

Unfortunately, I have some bad news for you. There's not much you can do to get more power out of these 4 bangers. These things weren't really designed to go over 70 mph for extended periods. About six weeks after I got mine I drove it 12+ hours (round trip) at 80+ mph on I-90 here in South Dakota. The only way I was able to keep it at that high of a speed was to keep my foot to the floor the entire trip. RPMs were through the roof (I don't have a tach so I can't tell you exactly what they were) and my gas mileage dropped significantly. Looking back at this trip I cringe - I really shouldn't have driven it like that. I didn't know anything about Jeeps at the time and assumed it could handle it. Just a few weeks after that trip I had a valve spring fail on me (that was a bugger to diagnose, let me tell you). I can't prove it but I highly suspect that working the engine that hard is what caused that spring to fail. I now avoid the interstate if I can and stick to two-lane highways - the drives are more scenic and enjoyable anyway.

New injectors may certainly help a bit, by all means swap 'em out. You could also try running an injector cleaner like SeaFoam through your gas tank. That's a slightly controversial topic around here - some people swear by SeaFoam and some people swear at it. I can tell you I've used it on different vehicles with mixed results. New injectors would obviously be better anyway.

Improving your air intake and exhaust may help things a bit. You can bore out your throttle body. One thing you can do for free is check your IAC - it's most likely filthy. Clean it up and the engine will be a little happier. If you buy a new one look at relocating it - see this thread for info. That's been on my to do list for a while.

Here's some links I've saved from my own research on this topic:

http://www.jedi.com/obiwan/jeep/2.5Lpower.html
http://www.fourwheeler.com/how-to/en...-power-adders/
http://www.jeepforum.com/forum/f9/2-...s-read-832754/

If you've got the budget for it, you could stroke your engine. There's a member here on this forum who stroked his 2.5L MJ to a 3.0L. Just thinking about a stroked 4 banger makes me drool a bit - hopefully I'll get to a point where I can attempt something similar.

Whatever you decide to do, let us know!

Outlaw Star

There's a few things you can do but they are not really cheap. The 2.5L is already tuned to its max save for a few small things. If you have the MPI instead of the TBI like me, you can bolt a 4.0L throttle body and spacer for more airflow. You can remove the restrictor from the airbox lid. You can add a high flow air filter, there is a long tube and short tube header available. Regear a little.
Now, it will never be a 4.0L or a rocket but Jeeps are not for speed and it is a reliable motor.
I custom stroked and built mine to 3.0L w/187hp and a 7K redline over the stock 117hp or 140hp (depending on AMC or ChryCo engine) w/4500 redline. But that costs a little.

bad_idea

Two letters and a number..... LS1. Disaster averted.

Outlaw Star

More expensive than a 4.0L swap. Just did one of those to a friends Comanche.

Ad-HocXJ

Glad to see another 4 banger! The most improvement ive seen on mine is from the 19lb 4 hole injectors and 4.0l throttle body.

-The injectors are shiny new and atomize the fuel better and are one of the best upgrades you can do without pulling the engine part IMO

-The 4.0l throttle body also lets more air in, and can be snatched off one the 4.0l guys who are swapping to a bored out throttle body.

-Many members have also seen improvements with aftermarket exhausts, although I can't say for sure

-Since we 4cyls have the 4.10 gearing, there is no real improvement to be had regearing (unless you want to spend a lot of money)

-Aerodynamic mods help the brick move alot, despite what most of the wheelers think here. Over on the ecomodder forum, lots of cherokee guys have found that the stock front/engine factory skid plate is very beneficial in reducing drag ,but it still won't make the Jeep a racecar.

-Also driving with the roof racks behind the B-pillar (as suggested by the owners manual) or removing it all together helps a small bit.

But in all in all, your puling a parachute with 4 angry squirrels so put some 4-hole injectors, a 4.0l throttle body, and a front skid plate and see how it feels. If it's not enough, you might be looking at mods worth $, or looking into a different Cherokee/vehicle.

I'm in the same boat as you, and want to pull G's with my box any way I can.

Here are some links to very reputable sources on making the 2.5l scream (or try to):

http://www.fourwheeler.com/how-to/en...-power-adders/

http://www.jedi.com/obiwan/jeep/2.5Lpower.html

4BangerDanger

Which injectors did you use?

Outlaw Star

Good sites but they only cover one out of the two 2.5L used. There was an AMC 2.5L amd the ChryCo 2.5L. Although the blocks and internals are the same, the air/fuel delivery is the main difference.

WyoCherokee

You can always stroke to a 3.0..... I had the 2.5 in my comanche, and it was "ok" at best. load her down with firewood in the bed, and it was pretty slow going. She got 27mpg though. Magnaflow muffler, 2" Exhaust, a good clean air filter, cleaned throttle body, new injectors, and a new fuel filter screen is about all you can do for a 2.5. I kind of wish i had a 2.5 4 speed cherokee for a DD

Outlaw Star

Hell, even so, all I got out of it was 187hp over the stock 117hp.

4BangerDanger

27 mpg? Nice! Best I have ever done is 24 mpg, and oddly enough that was in Wyoming! Must be that mountain air...

Ad-HocXJ

They were yellow 19lb Bosch Design III fuel injectors off ebay for $70.

These are the ones I got:
http://www.ebay.com/itm/172242421907?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
If you choose a different seller, make sure you get CLEANED ones! Not just used!!!!!

They were rebuilt with:

◦OHM Resistance Tested
◦Degreased and Cleaned
◦Stripped of all removable components
◦Two (2) Ultrasonic cleanings
◦Reverse / Back Flush
◦Spray pattern test
◦Leak down tested
◦Flow matched to +/- 1%
◦Install all new components (pintle caps, retainers, o-rings, seals, spacers & filters)
•Our flow matched injectors promote smooth engine operation and balanced fuel delivery reducing overall fuel consumption and harmful emissions
•Each injector works like new for a fraction of the price!!!

WyoCherokee

Yep. Laramie to Mountain Home Idaho!