Hey all, I have a 2001 XJ with the infamous "Bad Head". Long story short I got a NEW head and tore down the Jeep. I replaced the oil pump and rear main seal while I was in there, checked the pistons, rods and main bearings for wear/damage, all looked good. Replaced freeze plugs, water pump and therm. Put everything back together ( after doing the rear main seal twice because I used the wrong seal the first time! Doh!), filled with fluids and crossed my fingers.........I fired it up and the RPMs shot right up to 5 or 6 so I immediately shut it off and checked everything to make sure all sensors and vacuum hoses were hooked up properly. Everything matched the photos I took from before I tore into it. Tried to fire it again and it did the same thing every time I cranked it over. The motor sounded good besides the expected sputtering and smoking from everything in the system. What could cause this RPM hike? I can't leave the engine running long enough to throw a code. I do have a small leak in the oil pan ( I think I pinched the seal at the rear) and one freeze plug seeping. Obviously I have some more work to do but can anyone offer a suggestion on the RPM hike? Thanks in advance!

I've been reading the posts on this site daily for the last couple months getting ideas and info, so thanks for all your posts already.

 

are all of youre sensors on the throttle boddy hooked up? how about the linkage? i for got to hook up a snesore or linkage one time and it did the same thing.

 

Yeah I labeled everything really well, but I'm just wondering if one of the sensors is bad now. I don't know, I checked the connections and referenced my photos from before and they match up. I don't know which sensor would do that but I might have to try a little trial and error. Luckily I manage a NAPA so I have cheap access to parts. I might try unhooking a sensor or two and see if anything changes? Thanks!

 

TPS or ck for intake leak....disconnect throttle cable from TPS and see what it does.

 

It sounds like when you installed the intake it didn't seat correctly on the guider pins and you have a gap between the manifold and the block. been there done that. Same exact symptoms you are having.

 

Cool, thanks guys! I guess I have to take it apart again. Torquing the intake/exhaust bolts is a pain! Anybody have a good trick? I appreciate the help and I'll let you know how it goes.

 

Finally got it back together, the intake was definitely the culprit. I also found that I pinched the oil pan gasket so I ended up having to redo that too. I tried the method of using Permatex Hi-Tack on either end of the block and gluing the gasket to the block first, holding it in place with a few bolts without the pan. I let it dry for a couple hours and came back to it, installed the pan with no issues. Thanks for the help! I also wrapped the exhaust manifold with heat wrap and spray to try and cut down on the heat, we'll see how it works. It is taking a while to "bake on". I have run it a few times and smokes a little after it's warmed up, but no leaks anywhere so I'm sure it's just the wrap and spray getting cooked.

 

Hi, I'm in the process of repairing the cracked head problem. 0331 will forever haunt me, perhaps i'll play those number s in the lottery.

Anyway, I was wondering how you checked your crank and rod bearings. Did you mic or plasti-gauge them?

Best of luck and I'm sure I'll be contacting you in the future!

2000 Cherokee Sport