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  Topic Review (Newest First)
02-14-2020 06:42 PM
Gypsy_Botanist Hey, try this again. posted a reply to this twice already Its not taking!
It was my intake/exhaust manifold gasket. I guess moving around in the engine compartment knocked something loose. After I replaced it she drives better than ever. Hope your problems have all been solved.
01-26-2020 04:13 PM
Gypsy_Botanist
Quote:
Originally Posted by stephencbrinson View Post
Did you find a resolution... I have the exact t same issue after changing my water pump. IAC issues would be a random coincidence for me because I did not remove the air intake.

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I did figure it out. My intake/exhaust manifold gasket was bad. I guess my bumping around in there changing the water pump finally sent it over the edge. After I replaced it she ran better than she ever has.
01-26-2019 05:22 PM
stephencbrinson An update on my high idle revving issue....

it is fixed.

Installed a new exhaust/intake gasket and now idle at 750rpm and I can have a conversation with my passenger.

Along the way with this job, I repaired several vacuum lines, cleaned the intake manifold and throttle body, cleaned the injectors, new o rings in the injectors, and most importantly I used all seven of the needed bolts to hold the Intake /exhaust manifolds on.

Hope this helps some others.

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01-26-2019 10:55 AM
stephencbrinson In the process of replacing the intake/exhaust manifold to stop the exhaust leak noise and the high rev idle. Once I got past all the interference I noticed the intake manifold was loose. No wonder I have a vacuum leak and high idle....also, there are one 3 bolts holding the exhaust manifold and intake manifold to the head. And the thing still ran every day.

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01-22-2019 05:24 PM
stephencbrinson
Quote:
Originally Posted by bharris68 View Post
Stephen - good deal - when you do, there are alignment dowels and it's really critical to get everything lined up before and as you torque it down. I left a gap and the over-revving and TBI trying to compensate for air/fuel mix made a hell of a mess...
Thanks for the advice

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01-22-2019 05:19 PM
bharris68 Stephen - good deal - when you do, there are alignment dowels and it's really critical to get everything lined up before and as you torque it down. I left a gap and the over-revving and TBI trying to compensate for air/fuel mix made a hell of a mess...
01-22-2019 03:57 PM
stephencbrinson @bhar ris....I have a known exhaust leak at the manifold. I will be replacing the gasket this weekend. Since the exhaust and intake are the same gasket...I will update with my results.

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01-22-2019 03:38 PM
bharris68 To stephen and the OP - the Water pump on the 2.5 and the Power steering pump share a bolt or two from memory and I'm trying to remember if they hang off of the intake manifold?


If they do it's possible there is an intake system leak in Stephens case and in the case of the OP there is a block of Vacuum ports on the passenger side firewall.


OP: Use the UNLIT propane torch trick and wave it around the vacuum port block there on the firewall and if you don't see anything obvious unplugged, then you may come across cracked or compromised vacuum lines.


stephen - similar trick for you, but you'll be moving it near the intake manifold gasket very closely in order to get unlit propane near the gasket even as the fan blades are doing their darndest to blow the propane away! If you come across the leaking space, you'll need a set of feeler gauges to determine where the leak is. I would recommend against "Just tightening everything" because it's unknown if / where the issue could be. You don't want to overtorque the bolts and either break them off or wreck the gasket.
01-22-2019 09:13 AM
stephencbrinson
Quote:
Originally Posted by Gypsy_Botanist View Post
Hello all,

I am in need of some help. Been doing some updates/maintenance on my 93 YJ 2.5L. Changed the fuel pump and drove her over to my friends garage (it's heated) to change the water pump and fan clutch. Got everything back together and when I started her up the RPMs shot up to 2900-3000. We started to look at vacuum lines. We went through all the vacuum lines coming off the throttle body. We found some leaks, fixed them and used a vacuum pump to check the repairs. However when we started her back up the RPMs are still at 2500. She seemed like the RPMs calmed down a little but, still really high. Ran the self diagnostic and didn't come up with any codes. I am totally out of ideas for what the problem could be, please help and advise.



Thanks,

Ian.



I can also post pictures of things.
Did you find a resolution... I have the exact t same issue after changing my water pump. IAC issues would be a random coincidence for me because I did not remove the air intake.

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01-15-2019 09:23 PM
jsawduste Besides the TPS question and assuming the IAC is plugged in and the pintle seat is clean.


Take the intake plumbing off and slide a business card down over the air bleeds in the throttle body. These bleeds feed air to the IAC which in turn feeds air to the engine at idle. If blocking the bleeds off doesn't reduce the RPM than the engine is getting air from somewhere else.


If it does (you should be able to kill the engine by choking off the air supply) you know you don't have a vacuum leak.
01-15-2019 06:29 PM
SplitTailHunter A simple way to test vacuum and fuel pressure. You said you replaced the throttle position sensor, was this before or after the high idle ? If it was before you could have gotten a bad TPS..Put the old one back on and see if it idles down.. I've gotten a lot of bad sensors from the parts stores in the last few years





Edit : you might have gotten the spring on the wrong side of the arm on the tps...check and correct if necessary
01-15-2019 03:56 PM
blake989
Quote:
Originally Posted by Waternut View Post
Unfortunately, there isn't a good way to detect this without spraying a flammable liquid all over the engine compartment and listening for rpm changes.
I use a plumber's soldering torch with a propane bottle, not the self-igniting torch, the cheap one with only a valve. Crack the valve open and move it around potential leaks...works like a champ and has about the same odds of burning your face off.
01-14-2019 04:33 PM
Luuca do the simple things first.

1. Get some Throttle Body Cleaner (NOT Carb Cleaner) and remove and clean out your Throttle Body. A stuck or sticking IAS will cause high idle. Make sure the gasket below your TB is intact and in place.
2. Once the TB is cleaned out, run the engine. If it still has high idle, with the engine running, disconnect the IAS plug. if it continues to idle, you have a leak.

more than likely you cracked a rotted vacuum line somewhere while replacing the water pump. We have all had this type of "I checked it twice" moments and found that something was not as we assumed.
01-14-2019 03:17 PM
Waternut
Quote:
Originally Posted by Gypsy_Botanist View Post
Boojo I just tested each line, plugging one end and applying vacuum to the other and reading the gauge to see if it is holding a vacuum.
That only confirms that the vacuum lines you know of aren't broken. What's more likely is you've accidentally pulled a vacuum line off and don't realize it's disconnected somewhere. Especially near the front of the engine near the water pump where you were working. Unfortunately, there isn't a good way to detect this without spraying a flammable liquid all over the engine compartment and listening for rpm changes. Based on the 2500rpm idle that you're currently getting, slight rpm changes will be tough to detect. It may be better to try and listen around the engine bay for overly loud air intake noise. Feel around the fittings on the intake manifold as well. If you feel suction, that's it. It won't be a dangerous level of suction but probably best to do this while the engine is still fairly cool.

Does your jeep have the vacuum disconnect on the axle or vacuum lines running to the transfer case? Check those if it does.

If all of that fails, start plugging things the engine absolutely doesn't need with your hands for a few seconds and see if the revs drop. Things like any port on the manifold, brake booster line, and any other hose that looks like it's not held on by a clip or retainer.
01-14-2019 08:55 AM
Boojo35 I get now what you tested for vacuum. All things that the vacuum lines go to hold vacuum. There still can be a vacuum leak at the cylinder head to intake mating surface for instance. This can be checked by spraying that area with carb cleaner and listening for RPM changes. Keep in mind that carb cleaner is flammable when you use it. You can catch stuff on fire.

When you checked the gas pedal, did you look to see if the throttle valve actually closes?
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