'88 xj 4.0 185k, just recently drove from Maryland to Texas, did amazing. Shortly after getting here my ps sprung a leak, haven't replaced it yet, dont have the tools or the funds, she has been sitting for a while but she still runs fine, the other day it stormed pretty badly but didn't concern me too much, two days later i fire her up and she is idling a little lower and when I accelerate it feels like she is miss firing. Before I left I did a complete tune up, I checked the wires and vac lines, haven't pulled the plugs yet, planning on tomorrow, any ideas? Also I have a short ram air intake, if I sucked up water would it cause this?

 

check the sensors such as TPS, IAC, etc. usually issues regarding bad acceleration are caused by these, but if it is a missfire it could be a bad spark plug.
reason being, if water was sucked up through the intake. it could cause the plug to not fire correctly or not fire at all. if you think thats the issue give a day to possibly dry out and go from there.

 

It's been about a week, I changed the plugs, no change, I'm thinking maybe a clogged cat, because she is really loopy. Would water throw off the iac or TPS?

 

Depending on exposure, they're electrical units. And electrical, mass produced parts can go bad at anytime.
How's it idle?

 

I think you're overthinking this water thing. If you sucked up water, you would have known it instantly.

Did your complete tune-up include plug wires, cap, and rotor?

Is your air filter all oily?

Did you clean the throttle body when you did that tune-up?

 

What do you mean you "checked" the wires? You should replace your plug wires when you do a tune up. What all did the "tune up" consust of?

Check you throytle body sensors, especially the IAC. If it's dirty your Jeep is gonna run crappy. Pull the TB and the remove all the sensors. Clean everything up real well, put it allback together (new gasket for the TB), and see how she runs.

 

Before I left Maryland I replaced plugs, wires, cap, rotor, coil. Air filter is clean

 

She idles a little low but while I'm driving the rpms are constant not jumping around, and I don't have a lot of get up and go as I did before she started acting up

 

Clogged catalytic converter?
CRUISER’S VACUUM TEST FOR EXHAUST RESTRICTION
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.

 

This could also be your CPS (crank position sensor) Ive had problems with this in the past where it would sputter and sometimes die and when it totally gives out, theres no spark. Its a $60 sensor located on the bell housing of the trans and is very sensitive to heat.

 

Thanks for the input! I got her runnin back to normal. All she needed was the throttle body cleaned. Just drove my XJ from San Antonio, TX to westminster, MD. Absolutely no problems and even 17 MPG!

 

Back to basics. Congratulations. The throttle body/IAC cleaning is frequently overlooked. Should be done with every tune-up or right now if you don't remember doing it.
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The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

"Gently" wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled