Hey everyone, im new here and need a little help with a truck i just bought. I have built alot of 4.0 Cherokees but i'm stumped on this issue i'm having. Breakdown of the truck is this, 144,xxx miles, brand new transfer case and rebuilt tranny, cats have been cut off just has straight flowmasters super loud probably changing that, k&n intake, msd ignition, lifted with 35x12.5x15 mud tires, and some other exterior accesories. Heres my prob I cant figure out and I wanted to ask before I started throwing money in it like i do with jeeps (hence jeep mean Just Eats Every Penny) Most of the time truck is really strong starts great runs great tows great. But sometimes when starting from a dead stop or on the highway just cruisin it wants to sputter really bad then its fine. No codes. Can say I think its losing oil because oil gauge drops when near end of oil change, but i have no leaks or ever smell it burning. Was thinking of starting with plugs,wires, dist. cap, rotor, and tps which would be how i would diagnose my jeep but i just read something about the plenum on these going bad and i'm not to familiar with that? Any help would be greatly appreciated! And i just read some guy bashing these trucks saying hes going back his jeeps, um this truck rocks! If you cant dodge it ram it!

 

Check out the plenum thread stickied at the top of this forum. It will have a wealth of information for you, and that is an issue you need to address/verify first. If it's ok, the tune-up certainly won't hurt you any.

If it continues to be a problem, test the TPS.. (throttle position sensor) There are factory service manuals available for download in the faq section here as well. Having one is invaluable.

Oil pressure falling off some as oil ages is normal. Consumption is prolly due to blown plenum. (Mine goes thru quite a bit, but, I only get smoke at first startup of the day.)

Welcome to DF.

 

Thank you! Definitely missed that thread! Think i will change out the plenum gasket and do a full tune up. Any suggestions on plugs and wires for this truck? I know my jeep likes simple champion plugs, nothing special, and whats the proper gap for the plugs? Also when i say oil pressure drops sometimes the gauge will go completely to 0 and fluctuate. But it does only seem to happen at the end of an oil change and pressure checks out fine. Anything else I should look into as for oil sensors or is that kinda normal? Also, when i first got it and noticed the oil consumption i switched to a heavier oil and added lucas oil stabilizer to it and I think the thickness of that helped slow the loss of oil but it does eventuality get low enough to mess with the oil light. With that said, what oil should i consistently run in this for best results. I will say I use this truck! Its a daily part of my landscaping business so it is often weighed down or pulling a trailer so i want the best protection i can for this engine because it is really strong still and I want to keep it that way! Thanks again everybody! Heres a pic of my truck so far, when i got it it was custom painted like a harley, really cool but to much for me. Rt now it has a low gloss black metallic paint and i will be hitting it with clear coat soon. I really like the way it looks dark and not shiny, kinda like a tank

 

Do the timing chain and gears as well (double roller please) when you do the plenum, if your truck is over 100K miles. Water pump as well... since you have to take it off to get to the timing set. (yes, I am spending more of your money. )

Stick with good quality, copper plugs. Autolite 3923's are fairly popular. I use the Bosch Super Coppers, as that was all the parts store had enough of last time I bought plugs... they work pretty well. Gap is .035 I think. (it is on mine.... information should be on a sticker on the radiator support.)

Any reasonable quality wires will work. There is a Technical Service Bulletin (TSB) in the faq section for proper wire routing. Follow that as well.

Oil pressure sensors are common failure points.... replacing it while you have the intake out of the way certainly isn't a bad idea.