Hey guys. I'm new to the Cherokee world but not new to working on cars. I've been lurking on the sight and trying to find reason why my jeep, when started, revs all the way to redline. I recently replaced my head with a tupy head. I pulled everything apart and made the mistake of not labeling them when pulling it apart. I put everything back when it needs to be but I'm confused when it comes to the vacuum lines. when I was taking my vacuum lines off one broke so I replaced it with another hose. I have 3 lines that run into the back of the intake. One of them that I have I see most people just have a rubber plug over it. I think it's the climate control/cruise control line. I have cleaned my iac and throttle bottle. None of my accel cables are stuck either. I just bought new iac and rod and I'm going to try that. Anyone have any suggestions? Btw it's a 2000 Cherokee sport. Thanks for any input!

 

Does it rev high and stay there or rev for a few seconds and settles to a normal idle ?

 

As soon as I start it, it revs all the way up to 6k and stays there. I can't figure out why or can't find a vacuum diagram to see if I have any of them hooked up wrong. I cleaned up the throttle body and iac. I replaced the manifold gasket and made sure that the bolts are tight. I replaced the injectors with the 784's but it did it with the old ones in too. I also performed the flash. I'm at a dead end and can't figure out why it revs up to 6k and doesn't drop

 

Cover the throttle body air intake and see if it still revs. If it does you have a large vacuum leak. But I suppose you already knew that. Are you sure the bottom of the intake manifold is seated against the head?
This started when you replaced the head?

 

^^^^ Yes^^. I might cap ALL the vacuum lines on the intake for diagnosing. Maybe leave the vac to the brake booster for last, and cap that if it's still high. One to the Valve cover from the intake should have a 2.6 mm orifice/restriction. (the CCV "valve"). A big tube from the VC goes to the airbox, not the intake. Howdy Chuck!

 

Make sure you put the brake booster line back on when you swapped the engine out. That's a big hole for that hose and the connection is hidden by the big rubber hose that goes to the air cleaner.

 

Yeah this all started after I replaced the head. I'll double check the intake being seated properly. I'll try covering the throttle body but it's difficult doing it myself. Once I start the it I can't look under the hood to assess things because it revs all the way to 6k. I don't want it to sit at that rpm. I'm heading out now to change the iac and tps. Hopefully that works. Does anyone have a good diagram or picture of their vacuum lines?






I added some pictures to see if anyone can see anything I'm missing. The hose all the way to the left that plugged into the intake is a replacement. I broke the plastic one that was running from the leak protection pump. My climate controls selector doesn't work either. It's stuck on defrost/floor. Other then that I'm lost and ready to burn the jeep to the ground

 

Although it seems obvious to me (in the red) it may have nothing to do with the problem. But then again...sorry if it is a red herring guy!

 

You can't have any vacuum leaks into the intake manifold. That there Bill spotted is surely a problem if that goes to the manifold, and not the air cleaner. (my renix evap. can. tube, just vents to the airbox). In your first photo on post #7, that looks like a funky fitting on the intake. I might just cap things like that to trouble shoot it, then come back ind get it right after it's solved. You could be chasing all three, that fitting, the hole Bill circled and the IAC,,,For sure, fun like that happens!

 

Yeah thats the original hose I had on there before I replaced the head. That hole never made my idle scream to redline. And yes the far left vacuum hose is a little funky. The original hose that was on there broke and that's the only hose I had. I'm about to buy a cheap cigar and blow it into the intake

 

Kickdown and throttle cable adjusted properly ? I don't have that year, but the pic looks like an adjustment could be made on that throttle cable similar to kickdown one. I have a hard time seeing a simple vac leak causing 6k rpm's. But I don't have a solution either.

 

It can't go to Wide Open Throttle unless you have the throttle open or a massive leak in your intake manifold. Is your IAC (Idle Air Control) valve in or out? Also, if you remove the black hose to the air cleaner does it run any different with the throttle plate closed? You said you cleaned the TB but is the IAC damaged?

Also, tape that hole in the line to make us old guys happy LOL.

 

It was keeping me up at night.

 

I just put in a new IAC and TPS. I have tried removing each hose to see if anything different happens but it's still wide open. That hose with the hole is my old hose, I replaced it with a new one. I'm am at a complete lose. Anyone in the ATL area that wants to help a xj'er out?

 

I think you missed 67GMC point. You need to block the air coming into throttle body, then try and start it. The big black air tube bolted to TB can be removed and left that way while testing. Manually close the butterfly in throttle body, prevent it from opening with something that can't fall in by accident. Get creative block that air. If it starts and runs at all, you can rule out the TB, you have a big air leak elsewhere like intake/exhaust area.