2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

RPMs idle quickly after start up....

Thread Tools
 
Search this Thread
 
Old Jun 1, 2002 | 01:23 PM
  #1  
Thread Starter
brap brap
Tenured Member 20 Years
 
Joined: May 2002
Posts: 121
Likes: 0
From: Migrated back to Gulf Breeze, FL
RPMs idle quickly after start up....

Is this normal? I usually have it in first gear when in parked. I'll turn on the car, take it out of 1st and into nutruel and the RPMs will quickly go from 1500 and drop down (fast) to about 750. It normally doesn't do that, esp. when the car is cold. Most of the time, it'll idle at 3k, radatior will come on and drop slowly down to 750-1500.

Any ideas? Just being cauious over here.
Reply
Old Jun 1, 2002 | 08:02 PM
  #2  
vaughnc's Avatar
knowledge junkie
Tenured Member 10 Years
 
Joined: Mar 2001
Posts: 5,595
Likes: 6
From: Atlanta, GA
tap the gas during ignition and it should idle at 2500 rpms until it warms up then it should idle at 5-800rpms
Reply
Old Jun 1, 2002 | 09:34 PM
  #3  
RX7GT's Avatar
...must be a conspiracy
Tenured Member 10 Years
 
Joined: May 2002
Posts: 102
Likes: 0
From: Here, There, Everywhere
It is normal for the car to idle higher when starting due to what is called open-loop opertion. It is designed to help the engine reach proper operating temperature faster. It will also always rev higher when the shifter is in the neutral position than in any gear until after it gets warmed a bit (I'm not sure why it does this but they all do). The high rev is actually caused by a rich start which is necessary to ensure combustion in a cold engine (equivalent of a choke on a carburetor). A lot of the hard restart when warm after running problems are caused by the car going back into open-loop when the engine is turned off. The car does not realize that the engine is warm so it creates a rich start again and can flood the engine easily. I have this problem a lot and it is usally overcome by holding the gas all the way to the floor if the engine does not start after the first couple of spins. You should not hold the pedal down on a cold start in a fuel injected car nor should you touch the pedal until the R's drop down to around 1000-1500. The ECU will set and maintain the proper mixture (usually) for a cold start. If you hit the pedal during this phase, you can throw off the mixture and possibly flood the engine if it becomes necessary to restart it within the next few minutes. Be kind to your 7 and she will be kind to you. I always give my T2 an encouraging word right before any start. ---Jeremy

Last edited by RX7GT; Jun 1, 2002 at 09:37 PM.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
Jul 1, 2023 04:40 PM
Kyo
2nd Generation Specific (1986-1992)
6
Apr 13, 2019 09:24 AM
stickmantijuana
Microtech
30
Apr 23, 2016 06:37 PM
The Shaolin
2nd Generation Specific (1986-1992)
9
Sep 14, 2015 07:50 PM
CaptainKRM
2nd Generation Specific (1986-1992)
14
Aug 26, 2015 09:52 PM




All times are GMT -5. The time now is 03:48 AM.