91 4x4 Limited random sputters
 

Hey all! Been a while since I've been here. After making a ghastly decision to sell my last XJ for a "mom mobile" (Damn kids) I have finally come back from the dark side. :tongue_smilie:

I'm in a 91 XJ Limited 4x4 w/ the inline 6. I'm getting ready to do a complete tune up in 2 weeks (Thank you tax return!!) but I've recently noticed that shes randomly sputtering. I'm thinking spark plugs, wires, fuel pump or fuel filter but was wanting a "second" opinion.

I don't notice it so much while I'm driving, but that may be because its such a rough ride, but when I'm in park or in drive with my foot on the brake she just sputters randomly. Theres no "rhythm" to it, sometimes I can count to 10 and she'll sput, sometimes 3.

I'm hoping I'm using the right wording. By sputter I mean she sounds like she bogs out, loses umph.

I don't notice it quite as bad in park, but it is still there. What do ya'll think?

Thanks for helping a gal out.

Do the tune-up, then post your results. :) Just a 'fill up' or two before you put on all new parts, get a couple cans of carb cleaner and clean up the throttle body real good, inside 'n out. Run some gas treatment in your tank too. A lot of us like seafoam (read the can for all the ways to use it) Do all this 'cleaning' stuff before new parts.
Go with the cheap champion coppers plugs, fancy plugs (plats, splitwire, irridium etc) don't really help the 4.0L and they cost more. I'd suggest Napa for the dist. cap and rotor, they have brass contacts (bett than aluminum) Let us know how it goes :) Oh, and after all the new stuff, fresh oil 'n filter even if it's not time yet, and maybe tranny fluid/filter change. Coolant flush is probably in order as well.. you DO neglect coolant don't you? I know I do ;)

Sounds like the o2's are suspect. You got the right idea to just go right thru it and replace as much old stuff as you can..

Thanks so much.

There are 2 O2 sensors correct? I'm fairly sure 1 in under near the driver door area, but no idea where the other is. Suggestions?

I'd suggest you replace the upstream sensor first. The one nearest the engine, before the cat. The other one only monitors how well your cat is performing and won't affect performance.

So I unplugged the upstream sensor, the bogginess isn't as bad but its still there. So I'm going to go ahead and replace it in a couple weeks.

Replacing the plugs & wires this weekend & going to run some seafoam like it says (At least 30 miles) then change the oil & filter.

Fingers are crossed. Thanks so much folks!

Finish the tuneup with a new distributor cap and rotor; very important to the secondary ignition. And fuel filter and check air filter as well.

Tuneup hardware is critical. Let us know if it helps.

Thanks TJ. I'll be replacing everything else listed with income taxes. Just doing what I can afford this weekend.

Just reread your post TJ. I actually hadn't thought about replacing the rotor or dist. cap. In the past I've never messed with that unless I had to. Could you explain to me a bit about the importance or reasoning behind replacing it?

Other than the fact that it was recommended by the factory to be replaced every 30,000 miles along with plugs and wires? Only use replacements with brass, not aluminum contacts.

Throttle body cleaning is recommended at the same time, along with fuel filter replacement.

Thanks! Then I'll be replacing those with taxes as well.

Off to research cleaning the tb!


Ugh. I'm so scared I'm gunna put all this work into him & he's gunna go in shock & not run anymore lol

All of what you plan to do is money well spent. Your XJ will love you for it and reward you with better engine efficiency and better gas mileage.

And yes, you never want to ignore the distributor cap and rotor. They wear out! And they are not that expensive, so they should always be part of a tuneup.