High Idle When Slowing Down - Ranger-Forums - The Ultimate Ford Ranger Resource


2.3L & 2.5L I4 Tech General discussion of 2.3L and 2.5L I4 Ford Ranger engines.

Reply
 
LinkBack Thread Tools Search this Thread
  #1  
Old 07-03-2016
Member
Thread Starter
 
Join Date: Jun 2016
Location: Central Valley,California
Posts: 9
High Idle When Slowing Down

Only had this 98 4cyl Ranger for a few weeks and I have noticed that when the A/C is on and I am rolling to a stop with the clutch in the idle stays high for a few seconds and then today getting off the Freeway it stayed really high (like 3k) as I was rolling to a stop with the clutch in....

I guess what I am saying is that it just doesn't seem normal to stay at that high idle..... Yes eventually it does come down...Any suggestions on what the cause might be?

Thanks for your time LeeB
Reply With Quote
  #2  
Old 07-03-2016
Member
 
Join Date: Mar 2015
Location: Las Vegas, Nevada
Posts: 86
It could be the TPS that's causing the idling issue.
Reply With Quote
  #3  
Old 07-03-2016
Member
Thread Starter
 
Join Date: Jun 2016
Location: Central Valley,California
Posts: 9
Quote:
Originally Posted by mindtechno2015 View Post
It could be the TPS that's causing the idling issue.
TPS? Throttle P???? S???? What is it and where is it and how do I test it?

Thanks LeeB
Reply With Quote
  #4  
Old 07-04-2016
RF Veteran
iTrader: (1)
 
Join Date: Jan 2014
Location: Vancouver, BC
Posts: 7,595
It is normal for RPMs to stay high until speedometer is under 5MPH, it lowers emissions
Also when shifting gears RPMs should hang high for a few seconds when clutch is in.

When AC is on idle will be higher, that part is normal, but 3,000 seems excessive unless that's where you were at when clutch was pushed in.
Computer knows your speed so will hold RPMs high until speed goes down, but generally for only a few seconds, maybe 5 seconds, but it will stay above 1,200 until below 5mph

TPS is throttle position sensor, but while it might cause it I would think not since it can't really "control" anything, it is a sensor.

The IAC(idle air control) valve is what the computer used to set RPMs, it is an air valve that by passes the throttle plate, like a controlled vacuum leak.
Computer adjusts this valve to set RPMs, this is what is used to hold RPMs high when above 5MPH and when shifting gears, and computer opens it a bit more to increase idle when AC is on.

They are not hard to clean, and because it is a moving part it can get sticky after a few years.

Also check throttle itself, it does have a return spring on it, this has to be strong enough to pull the throttle plate closed against the air flowing into the engine, if it gets weak the throttle can hang open even though gas pedal is released.
Lube throttle cable as well they can get sticky
If you have cruise control, that's another cable that can hold throttle open longer than it should.


And just as a heads up for fuel injection and manual trans, never coast downhill in neutral, it will cost you money.
Nice thing about fuel injection over a carb is that the injectors can be shut off for 0 fuel usage.
So if you are going downhill in gear, foot off the gas pedal and RPMs are above 1,400 computer will shut off the injectors, 0 fuel use, if you push in the clutch and RPMs drop to around 1,100 computer restarts injectors.
With a carb you did coast to save money, it's opposite with fuel injection

Last edited by RonD; 07-04-2016 at 01:14 PM.
Reply With Quote
  #5  
Old 07-04-2016
Member
Thread Starter
 
Join Date: Jun 2016
Location: Central Valley,California
Posts: 9
Whoa...... Thanks so much for the info.. Being the truck is new to me I'll give them all the once or twice over... It will be a learning for me.......

Thanks again LeeB

After re-reading your post, your right it was only about 5 seconds and the rest you describe hits the nail on the head......

Thanks
Reply With Quote
  #6  
Old 12-21-2016
Member
 
Join Date: Dec 2016
Location: Columbus, Ohio
Posts: 8
First things I would do if you have no check engine codes is to clean the MAF sensor with appriate cleaner and replace the IACV (or atleast test it if thats possible). Ebay has good ones for cheap
Reply With Quote
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
98 4x4, rough idle, stutters while accelerating or slowing down, smooth at 2500 rpm likemytruck 4.0L OHV & SOHC V6 Tech 1 06-01-2015 09:39 PM
Engine shakes when slowing down from high speeds FordBigBoss454 2.9L & 3.0L V6 Tech 5 09-29-2014 09:04 AM
low idle when slowing down to idle j_huhnke General Ford Ranger Discussion 13 04-06-2012 05:58 AM
low idle when slowing down to idle j_huhnke 4.0L OHV & SOHC V6 Tech 2 03-25-2012 10:26 AM
slowing down... down hills... does yours do this? nross General Ford Ranger Discussion 26 12-09-2009 01:25 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -6. The time now is 10:57 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.