Question about 1993 Jeep Grand Cherokee

1 Answer

While in park the rpm jumped from 1000 down to around 700 and back up to 1000 what is the issue?

Posted by on

  • captncavmn Feb 04, 2010

    this issue is also when driving say you are on the road at 40 mph ..your rpms are at say 2000 while driving it will slightly jump from say 2000 rpms to 2200 rpms and back and forth..



1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Master
  • 3,230 Answers

Hi there,

Well the sources of the problem vary, but they are all related to the air intake system and simple to fix. 
1. The idle air control value (IACV) is stuck open or closed. Clean it (inside and out) with brake cleaner. If it still has a problem, replace it or bypass the water hose it uses to warm up the throttle body. This is an easy job to do on the street, but give yourself about 2 hours for any work you do on it AND have access to your ratchet set, screwdrivers, and possibly have a few new/small hose clamps on stand-by, in case one is busted or badly deteriorated. 
An IACV bypass should only be done if you live in a warm climate. Essentially, you re-route the water hose that comes from the motor and to the IACV. The re-route is routing the water from the motor back into the motor. Then you re-route the hose output/input on the IACV back to itself. Again, only do this in a warm climate. 
If you do this and the problem is still there, the ECU has discovered that the tempurature outside is too cold and you need to replace the valve.
2. The air/water return hose on the idle air control valve is busted open. simple... replace the hose/hose clamp. Then bubble/bleed your radiator.
3. The gasket between the air idle control valve and the throttle body is worn out. Replace the gasket if you can get it as a stand alone item.
4. The throttle body valve is extremely gunked up. This is usually an indication that the throttle body valve is sticking, but likely telling you that the IACV is stuck. The IACV sticks for two reasons... Carbon build-up and rust from radiator water corroding the valve. Please post comments if you need more help or information........

Good Luck!!


Posted on Feb 04, 2010


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Engine revs in park

This is called hunting. Can be caused by a bad mass air flow sensor. Could also be a sticking idle air control valve.

Jan 08, 2014 | Nissan Xterra Cars & Trucks

3 Answers

What is the idle speed for a chevy express 1500 2005 at the time of a tune up.

you never adjust the idle speed, it is computer controlled, if there is a problem then you must clean or replace the idle speed control valve and the throttle valve (clean only), final idle speed with a clean control valve is around 575 RPM

Nov 04, 2009 | 2005 Chevrolet Express

1 Answer

Idle fluctuation

Did you have this problem before?. I think it is just safety issue

Oct 03, 2009 | 1998 Honda Civic

1 Answer

Rover 75 v6 starts no problem runs 1000 rpm then

check idle speed sensor on your intake manifold around 700 to 750 rpm is normal ,air temp may efect idle speed .

Sep 17, 2009 | 1999 BMW 323 Series

1 Answer

2002 Wrangler 4.0 idles too high in park.

normal for an engine to start at elevated rpm and then die back as it takes a few seconds for the ECM doing it's sensor checks and idle back to the correct idle speed
check the idle rpm with an external rpm counter as most in dash units are inaccurate at rpm lower than 1000
as for the temperature
If you have a climate control module, it uses a mixture of heater and ac to maintain the temperature that you have set
so check it for operation

Nov 13, 2017 | 2002 Jeep Wrangler

Not finding what you are looking for?
1993 Jeep Grand Cherokee Logo

Related Topics:

73 people viewed this question

Ask a Question

Usually answered in minutes!

Top Jeep Experts


Level 3 Expert

79186 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22326 Answers

Kevin Daniels

Level 3 Expert

1455 Answers

Are you a Jeep Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides