2000 vaccum mystery. Low idle, ruff running. Picture. Missing tube on Intake. - JeepForum.com
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Unread 05-29-2012, 11:04 PM   #1
Duffboy
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2000 vaccum mystery. Low idle, ruff running. Picture. Missing tube on Intake.

2000 Cherokee 4 Door Spot
AUTOMATIC
6cyl ~ 4L
199k Miles
Recent head gasket repair, and 2 valves worked on, and corrected to hold vaccum.

It runs, but bobbles some time and idles low.

500 RPM at a stop, just under 700 RPM with A/C unit running, at a stop.

~Before purchasing owners friend replaced: Coil rail, Spark Plugs.
~I cleaned the crap out of the intake with Brake clean, and Carb clean on the injectors, got it pretty damn clean.

My thoughts were going towards a sensor~ TPS? CPS?
(Tried removing TPS but it ended up bending 2 torq head bits in a ratchet without ever budging screws?!, so I gave up and carb sprayed what I could)

Then today I remembered the missing tube plugged by a screw, I tried to trace it, but failed to find anything...

Ive tried looking online to see what this could be, but cant seem to pin point it...

Any more suggestions on the ruff/low idle? Need to figure it out so I can feel comfortable getting emissions testing done, anxious to start driving it

emissions.jpg   emissions2.jpg  
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Unread 05-29-2012, 11:34 PM   #2
cpdr26
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I'm not sure if there is any difference between the model years, but I have a 99 and if I'm correct, mine doesn't go anywhere. Its just a rubber piece that plugs up the hole. Everything else seems to match yours. If its the same I'm sure its just creating a vacuum leak because air is going past the threads
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Unread 05-29-2012, 11:56 PM   #3
Duffboy
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Haha, vaccum leak was a wild guess :P

I am no mechanic... Trying to problem solve my bad Idle without spending money.
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Unread 05-30-2012, 09:04 AM   #4
multmigs
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try something like seafoam or mopar top end cleaner both of which clean out entire intake and combustion chamber while engine is running...?
also at that miles I'd suspect O2 sensors
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Unread 05-30-2012, 09:10 AM   #5
BlindmeXJ
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I've owned my XJ for 12 years and it has the same hose with a screw just like yours!!
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Unread 05-30-2012, 09:30 AM   #6
CJ7-Tim
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Buy good quality tools like Sears Craftsman, or NAPA.

Remove and clean the throttle body, and Idle Air Controller (IAC). If you still have idle issues consider replacing the IAC.


Cleaning the Idle Air Controller (IAC) :

Purchase sensor safe Throttle Body cleaner spray.


1. Remove the Throttle body from the intake manifold.
2. Remove the IAC with a TORX 15 driver (2 bolts)
3. Gently wiggle out the IAC from the throttle body
4. Clean the IAC with Throttle Body Cleaner (not carburetor cleaner). Use cleaner, a rag, and a toothbrush. Be gentle; don’t twist or pull on the pintle as it is fragile and can be damaged easily
5. Also clean where the IAC seats in the throttle body with the same throttle body cleaner
6. While you have the Throttle Body off, give it a good cleaning also.
7. Reinstall IAC, the Throttle body, and check idle quality.

.
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Unread 05-30-2012, 02:36 PM   #7
Kalali
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On my 2000 that hose is definitely connected via a thin long vacuum size tube to somewhere near the firewall. I know because I had to remove it from the intake and mark it before I removed my intake manifold. As for the exact location on/near the firewall, I'll check when I get home.
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Unread 05-30-2012, 03:06 PM   #8
buildin1XJ
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My 99 model has that same plug on it but is capped off no screw in it. You might look at the big white sticker located on the drivers side firewall it will give you a detailed diagram of the vacum hoses. On mine it says that port is unused.
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Unread 05-30-2012, 03:49 PM   #9
CCKen
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That's a Bubba fix. There's supposed to be a rubber cap on that fitting. 1/4" as I recall. Do what CJ7-Tim says + get a cap from O'reilly or NAPA, they often come in kits with a varity of sizes.

Generally, vacuum leaks will give you a high idle, not low.
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Unread 05-31-2012, 12:35 AM   #10
Duffboy
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Cleaned the IAC as suggest, Idled high at 1k RPM for about 10 seconds then just dropped to 500RPM.

I am thinking more towards Oxygen sensors? Anyone?
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Unread 05-31-2012, 03:54 AM   #11
Kalali
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I checked and there is a vacuum hose from that nipple and goes into the firewall along with a bunch of other hoses/wires. I would have taken a picture but it is not easy to see with that side of the engine bay all disassembled. Mine is a '00 with build date on 02 00, if that matters.
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Unread 05-31-2012, 07:41 AM   #12
whitexj98
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Quote:
Originally Posted by Duffboy View Post
Cleaned the IAC as suggest, Idled high at 1k RPM for about 10 seconds then just dropped to 500RPM.

I am thinking more towards Oxygen sensors? Anyone?
Yeah start throwing parts at it.......

do you have a code reader that can view data? I would be looking to see if the iac is responding.
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Unread 05-31-2012, 07:49 AM   #13
jeepkid03
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Quote:
Originally Posted by Kalali View Post
I checked and there is a vacuum hose from that nipple and goes into the firewall along with a bunch of other hoses/wires. I would have taken a picture but it is not easy to see with that side of the engine bay all disassembled. Mine is a '00 with build date on 02 00, if that matters.
This. My 2000 has the same setup.
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Unread 05-31-2012, 06:02 PM   #14
Duffboy
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Quote:
Originally Posted by CJ7-Tim View Post
Buy good quality tools like Sears Craftsman, or NAPA. Remove and clean the throttle body, and Idle Air Controller (IAC). If you still have idle issues consider replacing the IAC.


Cleaning the Idle Air Controller (IAC) :

Purchase sensor safe Throttle Body cleaner spray.


1. Remove the Throttle body from the intake manifold.
2. Remove the IAC with a TORX 15 driver (2 bolts)
3. Gently wiggle out the IAC from the throttle body
4. Clean the IAC with Throttle Body Cleaner (not carburetor cleaner). Use cleaner, a rag, and a toothbrush. Be gentle; donít twist or pull on the pintle as it is fragile and can be damaged easily
5. Also clean where the IAC seats in the throttle body with the same throttle body cleaner

6. While you have the Throttle Body off, give it a good cleaning also.
7. Reinstall IAC, the Throttle body, and check idle quality.


.
Tried this, didnt do much. First second or 2 it was 1000 RPM, then just dropped to 500 RPM.

I decided to try out the same Oxy sensor safe throttle body cleaner on both oxygen sensors....

BIG mistake, now the jeep wont stay running and goes up and down from 50 RPM to 500 RPM then boggs down....


Ordering Oxy's from Rockauto NTK brand.





Thank you for all the suggestions, I saw the diagram on the back, and yes it says unused for the nipple.

Going to replace the Oxygen sensors and go from there! $80 mistake, should of just been happy with 500 RPM
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Unread 11-26-2013, 07:48 AM   #15
NYSLC93
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I have a 2000 XJ and there's no cap or tube on the nipple, and as such it's throwing a P1494 code.

I'm assuming that there is supposed to be a vacuum line connected here (not a cap) as when I put my finger over the hole when idling, the jeep nearly stalls.

Does anyone what a P/N for this vacuuum line (or what they used to replace it)?

Any pictures of where this is supposed to connect to?

Thanks!

Quote:
Originally Posted by Kalali View Post
I checked and there is a vacuum hose from that nipple and goes into the firewall along with a bunch of other hoses/wires. I would have taken a picture but it is not easy to see with that side of the engine bay all disassembled. Mine is a '00 with build date on 02 00, if that matters.
jeep-vacuum-line-circle.jpg

photo-1.jpg

photo-4.jpg

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