High RPM

Reply Subscribe

Thread Tools

Search this Thread

Mar 12, 2007 | 06:36 AM

gekitch111

Thread Starter

New User

Joined: Jul 2005

Posts: 22

Likes: 0

High RPM

I am having trouble with the RPM on my '90 bronco. The RPM is high when I first start up. Sometime up to 2500 rpm. This problem is intermittent after it warms up. I have a manual transmission so needless to say it is hard on the transmission. Any ideas?

Mar 12, 2007 | 07:16 AM

dcf4x4

Laughing Gas

Joined: Apr 2005

Posts: 910

Likes: 8

From: West-Central New York

In my professional opinion as a fense contractor, I'm fairly certain it's the idle control sensor. (at least that's what i think it was called)

My bronco did the same thing last year, but not so high, and I replaced the sensor and it runs great now.

Mar 12, 2007 | 07:29 AM

gekitch111

Thread Starter

New User

Joined: Jul 2005

Posts: 22

Likes: 0

Any idea where it is located? Is it part of the idle air bypass controller?

Mar 12, 2007 | 08:00 AM

mprice

Elder User

Joined: Feb 2007

Posts: 601

Likes: 1

From: Chicagoland

Quote:

Originally Posted by gekitch111

Any idea where it is located? Is it part of the idle air bypass controller?

They are the same thing. It's amazing how a simple part can have so many different names. Make sure you check codes before you get on this replace-a-part merry-go-round. There isn't really a sensor for this; the ECU sets up a control loop between the RPM reading and the IAC to try and hold the RPM at a given point for the mode (warmup, idle). There are many ways this could go wrong, but the IAC is certainly the usual suspect.

You might try pulling the IAC and mucking it out with throttle body cleaner to see if it is just gunked up before you replace it.

Mar 12, 2007 | 08:04 AM

gekitch111

Thread Starter

New User

Joined: Jul 2005

Posts: 22

Likes: 0

I will try that. I have replaced this 2X but usually I have a problem with low idle. I noticed the problem the first time when the A/C would engagee in defrost mode. Thanks for the help. This is just the best site for information!

Mar 12, 2007 | 02:56 PM

autx790

Senior User

Joined: Oct 2005

Posts: 125

Likes: 0

From: South Carolina

I had the same problem, which over time the idle speed got progressively worse (higher) I did it backwards. Replaced IAC, that didn't fix it, checked voltages on my throttle position sensor (instructions in haynes manual), found they were bad. Then I checked codes and it said this was my problem. I replaced it and now I idle at 700 RPM roughly.