ScottLs 2001 XJ

[Bradywgn71 1,008]

You're OBD2, right? Have a scan tool hooked up to see the actual RPM. Check it against specs. Factory tachs are notoriously inaccurate. At least then, you're not guessing what the hash marks mean and will give you a point of reference.

[scottL 185]

what is the factory spec on yours for idle after warm-up?

 

Quick google search revealed nothing. I feel strongly it's higher than where mine idles at now. I did find this though, my problem is exactly the same as dude's: https://www.ifixit.com/Answers/View/76792/Idle+problem+remains+a+odd+frustrating+headache+after+much+work he said replacing his battery did the trick "enough" for him & that he eventually sold the vehicle without a known fix. I replaced my battery right before the rubicon trail last year.

Then some other guy in the above thread link talks about a vacuum leak potentially being the culprit.

I think if I had a vacuum leak, wouldn't that have registered on my OBDll scanner when I plugged it in on top of the mountain at Cinders? & why does it idle perfectly normal on cold start until after the first time I shut it off??

One guy said the factory idle specifications were on a vehicle tag located inside the driver door jam of his Wrangler. I'll verify that when I can get to my jeep later today.

[scottL 185]

You're OBD2, right? Have a scan tool hooked up to see the actual RPM. Check it against specs. Factory tachs are notoriously inaccurate. At least then, you're not guessing what the hash marks mean and will give you a point of reference.

 

Yessir. I don't know that my scanner has an actual rpm gauge but i'll check when I get home. It'd be nice to know where I'm really idling as opposed to listening and guessing whether or not it's within spec. Thanks for the tip.

[jgaz 750]

You still have plug wires on that motor, correct? If that's the case I have an Snap On, inductive pick up, tach dwell meter, left over from my dealership days. It was state of the art in 1985. Dont laugh, I started out installing points in 1973. This tool would certainly tell you RPM if you don't have an alternative method.

 

It's not like I use it much thee days. Lol! If you want to borrow it, I'm up in Peoria.

 

Jim

[jgaz 750]

BTW: You could run the pick up under the hood and drive the Jeep with the the meter on the seat beside you. It could be powered from the cig. Liter plug. I used to use it that way during the early 80's to check the dwell on carburetor mixture control solenoids. Dwell time on this solenoid helped to establish if you had a rich or lean condition.

 

Okay, enough with the "way back machine". I see you nodding your head Tim.

[theksmith 5,778]

Jim, he has coil on plug ignition.

 

Scott, any OBDII tool should give you your RPM.

 

WJ's are notorious to run strange when the battery isn't quite up to snuff, sounds like maybe XJ's too. if you have a multimeter check your battery voltage when the rig is off and when running and let us know the results.

 

given the age of the rig (rubber hose deterioration) and the fact it started while bouncing around offroad and at higher elevation - my money is on a small vacuum leak... that wouldn't throw any specific code for you either.

 

my old XJ started to die randomly sometimes and it was a bad vacuum hose connector over near the cruise control actuator thingy (technical term). supposedly you can use propane to find such a leak, but i've never had good luck with it on really small ones - we could give it a try though.

 

offer still stands to bring it over if you need a multimeter, OBDII stuff, propane torch, or an extra hand!

[scottL 185]

Thanks for the offer Jim.

 

Could be a vacuum leak somewhere K. I've heard of checking for vacuum leaks with carb cleaner but not propane? What are you doing after church tomorrow? I could swing by.

[theksmith 5,778]

fix your 4lo?

[scottL 185]

Not yet. Ever since I got back from the Rubicon trail, it is damn near impossible to shift into 4 low. The shifter won't go back far enough to engage. & if I can get it into 4 low, shifting the transmission into reverse then makes a loud clunking sound like dropping a bowling ball onto a piece of sheet metal. When I look under my jeep the transfer case is now sitting directly on the metal part of my transmission mount where someone at 4 Wheelers supply had notched said mount to make room for the thicker 241 transfer case. After getting the work done I noticed it was very close with barely any polyurethane to cushion it. Since then something must have shifted as the 'case is now resting directly on the metal part of the mount.

Talked to George about it last week. He said Diane's Cherokee had a similar problem with her shifter that he managed to fix with customized mojo. Since we both got our Rubicon transfer cases installed by 4 Wheeler's last year I am hopeful he can get mine working right too. If what fixed Diane's jeep also fixes mine then great. If not, I'll most likely have to find a 4 wheel drive fabrication shop who knows how to return customers' phone calls and can also align my transfer case properly.

I don't think it's far off really. Just need to remove the belly skid and do some reconfiguring. I could go to Harbor Freight, get a tranny jack & attempt to re-align the t-case myself. I'm reluctant though because it'd take me forever to do it right & I need the jeep to drive to work every day.

[theksmith 5,778]

no tranny jack needed for this. just a regular floor jack and a block of wood between it and the t-case body will lift everything up so you can change the trans mount or fiddle with it.

 

how old is this poly trans mount - could it just be squished toast? do you know if they notched/lowered everything just so the t-case didn't hit the floor pan, or because of vibes?

 

i'm sure Joe could work on this for you now that he has a shop, and he is good about returning phone calls... however, you can do this - get under there! see if we could just raise the whole tranny mount temporarily with a couple blocks/strips of metal for a short term solution?