upgrades for 2.5L

[Mobius1]

I don't have the money for a engine swap and who knows how long that will be. So for the time being what mods can be done to the 2.5L so it'll run better, stronger and not be so sluggish on the highway? Also is there supposed to be a rear sway-bar on these trucks? Noticed today in my car that a few of the smaller trucks I was passing had a rear sway-bar and when I got home noticed my MJ does not. If it helps for any further comments and such its a 88 short bed 2wd.

[JeepcoMJ]

nope, no rear swaybar.

 

as for upgrades, there are none. obviously cold air intake could help a bit, new plugs and wires, cap and rotor.

 

basically nothing else will make them better save a turbo kit which would require a newer 2.5 or at the very least theharness etc. from a 91+ 2.5 as they have multiport fuel injection rather than TBI

[Pete M]

In my opinion, the best things you can do are routine maintenance and then gears, gears, and more gears. What trans do you have and what size tires? Done a tune up recently? Running the original cat?

[Mobius1]

Has no cats, new plugs and wires 2 months ago and cap still looked brand new since when I got it that was the cleanest thing under the hood. As far as I know they are the stock tire size but I really wouldn't know what that is since i've only had the truck several months now (Tire size P235/75R15).

[JeepcoMJ]

what transmission do you have?

 

if it's auto it should be 4.10 or 4.56, if you have a 5 speed you should have 4.10's, and if you have a 4 speed you should have 3.55's.

[Mobius1]

Its and Auto but I have no clue what tranny it is. I guess if there is a certain spot to look I can try and look it up real quick. Also was reading another post and they had mentioned blue smoke comming out the exhaust...what does that mean?? The CAI that was mentioned as a possible upgrade (cold air intake), where on earth would I pick something up for the MJ or is one of those make it your self type of thing?

[FxRacing282]

well, you can get header pipe from summit racing, filters, plugs and oil are about all you can do to stay cheap. a cold air intake off of a XJ (cherokee) will work as the seats foreward are the same. Throttle body spacer will help too. ill go with Pete, if that isnt enough re-gear it. if you have some mechanical skills and some time you can take a whiz tool and port/polish your throttlebody.

[feerocknok]

What year is it? '86 is the TF904, and the best upgrade you can do with that transmission on the truck is to get rid of the tranny, with either an '87+ auto or manual.

Also, an '86 auto will have 4.10 gears (most likely), so 4.56 gears out of an '87+ auto would be a good upgrade.

[Mobius1]

Its an 88 Pioneer. Well so far everyone has mentioned everything I had thought of a side from re-gearing it which I won't be around to do that or have the money. Oh well i'll just do that small stuff, CAI and TB spacer and see where it goes from there.

[JeepcoMJ]

I can tell you now that that other stuff isn't going to give you any noticeable power. only regearing it will give you more power, but then you lose top end.

[Mobius1]

Thats fine, at the very least it'll have a bit more kick around town and i'll have the feeling that I accomplished something before I left for basic. :D

[JeepcoMJ]

:-/ I put a K&N on my 2.5 xj and all I feel is that I wasted money...so I put it on a different jeep.

[mjeff87]

I've got a K&N flat filter on my 2.5....can't tell the difference FWIW (but someone gave it to me for free so there's no money lost)

 

If your '88 is factory original, you have an AW4 tranny, and 4.56 gears stock in your rearend (a fairly rare combination, congratulations :D ) You could probably improve your highway mileage a bit with a larger tire, like a 30" one. I've got 4.56's under mine with 31" AT's, which is just about perfect for me....still has enough oompfh to get out of it's own way, and I can still use OD on the interstate (flat) and keep up with traffic at 65-70 mph at about 2500 rpm. 4LO and the thing is a tank. It's just about the same as it was when 2WD with 4.10's and 28" stock tires.

 

Jeff

[Mobius1]

Well all in in all its great just on the highway if I need to speed up, going up any sort of hill or there is a slight breeze i've got nothing. Only way I get anything is if I floor it and it drops a gear to speed up. Also its done this 4 times already. When I get done driving on the highway and i'm comming to a stop or I am stopped the Oil light comes on and some times it'll flicker but goes away when i let my foot off the brake and start going....whats up with that?

[mjeff87]

do remember.....you are driving the aerodynamic equivalent of a toaster with a small swimming pool attached to it :D I'm driving a rental car now (Dodge Charger) that's a 4 cylinder that'll absolutely get me into big trouble if I don't watch the speedo. The driveline is so tight and the road noise is so minimal that you don't realize you're taching upwards of 3500-4000 rpm in "normal" driving situations. I drive my MJ by sound, not speed..........I know how fast I'm going by what all is rattling and sounding like it's going to explode, I don't need to look at the speedo ;)

 

For the OP light, I'd recommend an oil change with a new filter (not a Fram). See if that fixes things.

 

 

Jeff :cheers:

[Mobius1]

well its not quite due for an oil change since I don't drive it enough. I drive it like maybe 2 times a week and thats just because my car is low on gas and I hadn't gotten paid yet. Whats wrong with fram oil filters by the way? I know I have the aerodynamics of a barn but when i'm getting passed by a wrangler that is the same age and motor I start to get a bit annoyed. Well unless some one has something else to add to this thread that has not been mentioned its starting to sound like we are beating a dead horse. Thanks for all the input people, let ya know how goes in a week or two.

[feerocknok]

Fram's had some problems with quality control that has caused either no filtering or super high oil pressure by filtering too heavily. Both of those things can destroy your motor.

Conventional oil breaks down with time, not just mileage. Try to change your oil every 6 months, even if that's only 1500 miles.

[carnuck]

First, stock tire is 205/75/15 with 4 cyl auto. You probably have 3.73 gears (4.10s would be better with your tire size) 3 speed auto is 904. 4 speed auto (O/D) is AW4 and much better on fuel and strength.

Do you have 4 injectors or just 1 in the throttle body? A can of Seafoam will help the power a bit by cleaning the injectors. If you have 4, then you can upgrade to the 4.0L throttle body (check the sensors are mounted the same and base pattern matches first) That's what the TJ guys do for upgrade.

 

Exhaust leak can actually rob power (top end especially) and a sticking EGR valve will cut power (I left the hose off mine for testing back in '99 and forgot to put it back on)

[FxRacing282]

First, stock tire is 205/75/15 with 4 cyl auto. You probably have 3.73 gears (4.10s would be better with your tire size) 3 speed auto is 904. 4 speed auto (O/D) is AW4 and much better on fuel and strength.

Do you have 4 injectors or just 1 in the throttle body? A can of Seafoam will help the power a bit by cleaning the injectors. If you have 4, then you can upgrade to the 4.0L throttle body (check the sensors are mounted the same and base pattern matches first) That's what the TJ guys do for upgrade.

 

Exhaust leak can actually rob power (top end especially) and a sticking EGR valve will cut power (I left the hose off mine for testing back in '99 and forgot to put it back on)

 

well an exhaust leak can also give you net torque and net horsepower gains also. it depends on where and how big. i would suggest if you need a new muffle for inspection drill 2 holes about 1/4" in the intake side of the muffler, as long as its behind the cab. (mild CO poisoning is terrible)

[Mobius1]

aside from having to put a new midpipe on (past owner removed cat and the welding had failed started running open header) everything exhaust is pretty sound.