3krpm idle
My intake manifold worked itself loose, my idle jumped to 3500 RPM. I tightened it back down and made sure it was seated properly, but it's still sitting at 3kprm now. The battery gauge was originally at zero before when it happened and the check gauges light came on. Now, it sits at around 12V.
Does anyone have any ideas?
Does anyone have any ideas?
Senior Member
Joined: Sep 2014
Posts: 896
Likes: 2
From: Phoenix, A-to-Z
Year: 1988
Model: Cherokee
Engine: 4.0
If the manifold fell off, some hoses may have popped out with it. MAP sensor hose perhaps? I don't know if that would result in fast idle.
The intake gasket forms to the shape of the intake surface and the head surface. If it gets shifted a bit, the imperfections in the mating surface that got pressed into the gasket when it was first installed may not align just right and would result in vacuum leaks. You can use a stethoscope to find out for sure...
The intake gasket forms to the shape of the intake surface and the head surface. If it gets shifted a bit, the imperfections in the mating surface that got pressed into the gasket when it was first installed may not align just right and would result in vacuum leaks. You can use a stethoscope to find out for sure...
CF Veteran




Joined: May 2012
Posts: 7,965
Likes: 964
From: Lost in the wilds of Virginia
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
If the manifold fell off, some hoses may have popped out with it. MAP sensor hose perhaps? I don't know if that would result in fast idle.
The intake gasket forms to the shape of the intake surface and the head surface. If it gets shifted a bit, the imperfections in the mating surface that got pressed into the gasket when it was first installed may not align just right and would result in vacuum leaks. You can use a stethoscope to find out for sure...
The intake gasket forms to the shape of the intake surface and the head surface. If it gets shifted a bit, the imperfections in the mating surface that got pressed into the gasket when it was first installed may not align just right and would result in vacuum leaks. You can use a stethoscope to find out for sure...
Yep, to all of the above.
IF you don't have a stethoscope, try spraying brake cleaner or WD-40 around the area where the gasket is. If there's a leak there, you'll hear it.
I sprayed some pb blast around there, didn't really hear anything different. I'll probably just go ahead and replace the IAC and clean the TB. I'll probably just replace the TPS too while I'm messing around.
**** I may just go ***** out and get a new gasket and new bolts too and just replace that gasket while I'm at it. Anything else while I'm in there rooting around? I'll get the motor mounts done finally too I guess.
**** I may just go ***** out and get a new gasket and new bolts too and just replace that gasket while I'm at it. Anything else while I'm in there rooting around? I'll get the motor mounts done finally too I guess.
Last edited by mr white; Nov 17, 2014 at 05:30 PM.
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Senior Member
Joined: Nov 2014
Posts: 603
Likes: 1
From: Hacienda Heights
Year: 1990
Model: Cherokee
Engine: 4.0
Never use brake cleaner for this or any other operation where it'll be burnt in the engine, it can kill you. Most cautions are over rated but this is for real. It can cause permanent severe lung damage severely shortening your life and even instant death.
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
What on earth kind of brake cleaner are you using??? Stuff I buy is nearly lighter fluid
CF Veteran




Joined: May 2012
Posts: 7,965
Likes: 964
From: Lost in the wilds of Virginia
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
Whoops! I think he's right, Green Leafy One. When I read his post I remembered being warned about that in a welding class I took a few weeks ago. It turns into phosgene, which is a nasty nerve agent.
https://duckduckgo.com/?q=brake+clea...to+nerve+agent
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Whoops! I think he's right, Green Leafy One. When I read his post I remembered being warned about that in a welding class I took a few weeks ago. It turns into phosgene, which is a nasty nerve agent.
https://duckduckgo.com/?q=brake+clea...to+nerve+agent
CF Veteran




Joined: May 2012
Posts: 7,965
Likes: 964
From: Lost in the wilds of Virginia
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
Okay, turns out it's not a nerve agent, it turns into hydrochloric acid when it hits your lungs and sinuses.
For any reading who think this is no big deal, please read this:
For any reading who think this is no big deal, please read this:
By the next Monday, nine days after the poisoning, I lost all balance. I was confused and could hardly talk, so I finally went to the emergency room. My symtoms were low O2 level, sugar levels out of control, vertigo, and I was hurting badly in my entire chest. I was admited and put into ICU. My kidneys had probably shut down for those first four days. My lungs were damaged, so I had to be on O2. I had to be on insulin to keep my sugar in check. Since there is no antidote for phosgene, all I could do was try and rest and hope I got better. After CT, MRI, EKG, and EEG tests, as well as several blood tests it looked like, at least for now, there is no permanent damage. However, the MRI showed fluid in my sinuses and a buildup of fluids near my brain. The phosgene scarred my sinuses, which then became infected. The three doctors I saw said I was really luck to make it.
After four weeks, it appears that I may have emphysema and chronic bronchitis. I'm on nasal medicine and an inhaler. My sinuses are severely scarred, and my smell nerves are damaged. I still have that awful chlorine taste and smell. I may also have pancreas damage. The insulin that I was taking had little effect on my sugar levels, so I'm now on some stronger medicines.
After four weeks, it appears that I may have emphysema and chronic bronchitis. I'm on nasal medicine and an inhaler. My sinuses are severely scarred, and my smell nerves are damaged. I still have that awful chlorine taste and smell. I may also have pancreas damage. The insulin that I was taking had little effect on my sugar levels, so I'm now on some stronger medicines.
Senior Member
Joined: Nov 2014
Posts: 603
Likes: 1
From: Hacienda Heights
Year: 1990
Model: Cherokee
Engine: 4.0
20+ years ago I used some brake clean on a carburetor on a running engine. I caught a whiff of the exhaust and it paralyzed my diaphragm, couldn't breath in or out. It didn't last a long time, just enough to freak me out. Many years later I read the story BlueRidge posted. I was lucky to not get enough in to do major damage. Some formulations may not have these effects but I've just made it a rule to not mix fire and brake cleaner.
The other issue with spraying brake clean ***** nilly on a motor is that it attacks plastic, rubber, sealants, paint, etc.
The other issue with spraying brake clean ***** nilly on a motor is that it attacks plastic, rubber, sealants, paint, etc.


