Rough idle when engine cool - Ford Truck Enthusiasts Forums



1999 - 2003 7.3L Power Stroke Diesel  
Sponsored by:
Sponsored by:

Rough idle when engine cool

Reply
 
 
 
Thread Tools Search this Thread
  #1  
Old 10-11-2017, 12:50 AM
Keabler's Avatar
Keabler Keabler is offline
Senior User
Thread Starter
 
Join Date: Jul 2017
Location: Yuba City
Posts: 111
Keabler is starting off with a positive reputation.
Rough idle when engine cool

Now that I've been really digging into my truck, one of the things that bothers me is that the truck runs so rough when I first start. When cold, it is just louder and a bit more sluggish feeling. Once warmed up it purrs like a kitten... Well, a lion perhaps, but it's smooth and even.
What causes that?
Reply With Quote
  #2  
Old 10-11-2017, 06:25 AM
Walleye Hunter Walleye Hunter is offline
Postmaster
 
Join Date: Mar 2014
Location: Douglassville, PA
Posts: 3,416
Walleye Hunter has a great reputation on FTE.Walleye Hunter has a great reputation on FTE.Walleye Hunter has a great reputation on FTE.Walleye Hunter has a great reputation on FTE.Walleye Hunter has a great reputation on FTE.Walleye Hunter has a great reputation on FTE.
I don't know all the reasons but two that come to mind are some failing glow plugs and oil choice can make a big difference when cold. A good 5w-40 synthetic is recommended in colder climates.
Reply With Quote
  #3  
Old 10-12-2017, 09:09 AM
Keabler's Avatar
Keabler Keabler is offline
Senior User
Thread Starter
 
Join Date: Jul 2017
Location: Yuba City
Posts: 111
Keabler is starting off with a positive reputation.
Quote:
Originally Posted by Walleye Hunter View Post
I don't know all the reasons but two that come to mind are some failing glow plugs and oil choice can make a big difference when cold. A good 5w-40 synthetic is recommended in colder climates.
I'm using Delo full synthetic 5w-40. when I say cold start, I'm talking like 60 degrees. It just runs louder and more obnoxious until it's been running for a bit. Not sure what could cause that.
Reply With Quote
  #4  
Old 10-12-2017, 09:20 AM
jimjokjv jimjokjv is offline
Senior User
 
Join Date: Jun 2017
Location: Arizona
Posts: 148
jimjokjv is starting off with a positive reputation.
Just curious but do you have a California Emissions truck with a glow plug control module instead of a relay?
Reply With Quote
  #5  
Old 10-12-2017, 09:24 AM
Keabler's Avatar
Keabler Keabler is offline
Senior User
Thread Starter
 
Join Date: Jul 2017
Location: Yuba City
Posts: 111
Keabler is starting off with a positive reputation.
Quote:
Originally Posted by jimjokjv View Post
Just curious but do you have a California Emissions truck with a glow plug control module instead of a relay?
I am in CA, but not sure. It was originally an Oregon truck. I have the build sheet from dealer. Where would it say if it was California emissions? It says less catalyst, so maybe not?
Reply With Quote
  #6  
Old 10-12-2017, 09:39 AM
jimjokjv jimjokjv is offline
Senior User
 
Join Date: Jun 2017
Location: Arizona
Posts: 148
jimjokjv is starting off with a positive reputation.
This is a Glow Plug Control Module which should easily be seen on the passenger's side top of the engine just in front of the Turbo assembly.
The reason I ask is that I have the California Emissions set up on my truck and experience the same cold starting problems you are.
My research to this point tells me the glow plugs are operating but may not be operating as designed due to an incorrect PCM being installed by a previous owner.
Reply With Quote
  #7  
Old 10-12-2017, 09:40 AM
andym's Avatar
andym andym is offline
Post Fiend
 
Join Date: Mar 2002
Location: Florence SC
Posts: 18,574
andym has a superb reputationandym has a superb reputationandym has a superb reputationandym has a superb reputationandym has a superb reputationandym has a superb reputationandym has a superb reputationandym has a superb reputationandym has a superb reputationandym has a superb reputationandym has a superb reputation
Look under the hood for one of these:
Amazon Amazon
on the passenger side valve cover.

You will either have one of those, or two large brown relays on top of the motor, one for the AIH and the other for the glow plug relay. You will either have a GPCM or a GPR.

Ohm out your glow plugs and replace them if necessary. It's not that hard to do, just a little time-consuming, especially if it's your first time taking the valve covers off.
Reply With Quote
  #8  
Old 10-12-2017, 09:51 AM
Keabler's Avatar
Keabler Keabler is offline
Senior User
Thread Starter
 
Join Date: Jul 2017
Location: Yuba City
Posts: 111
Keabler is starting off with a positive reputation.
Quote:
Originally Posted by andym View Post
Look under the hood for one of these: https://www.amazon.com/Glow-Plug-Mod.../dp/B009VI5G38 on the passenger side valve cover.

You will either have one of those, or two large brown relays on top of the motor, one for the AIH and the other for the glow plug relay. You will either have a GPCM or a GPR.

Ohm out your glow plugs and replace them if necessary. It's not that hard to do, just a little time-consuming, especially if it's your first time taking the valve covers off.
Thank you. It looks like I have a gpcm. Here's a picture.


I didn't know the glow plugs would affect the running of the truck, so much. I thought they just wanted it enough to start. I'll ohm the flow plugs this weekend. As far as the relay, it's this worse than the two modules? Is there something I should change?
Reply With Quote
  #9  
Old 10-12-2017, 09:57 AM
cleatus12r cleatus12r is offline
Postmaster
 
Join Date: Apr 2004
Posts: 4,641
cleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputation
Rhythmic misfire? If so, it's injector time (or shimming the armature plates at a minimum).

Rough, rhythmic (as in not "hitting" on one or two cylinders) misfire without smoke until the engine is warm means non-firing injector(s). The excessive noise or rattle is because the next cylinder in the firing order is working for itself and the cylinder before it.
Reply With Quote
  #10  
Old 10-12-2017, 10:09 AM
Keabler's Avatar
Keabler Keabler is offline
Senior User
Thread Starter
 
Join Date: Jul 2017
Location: Yuba City
Posts: 111
Keabler is starting off with a positive reputation.
Quote:
Originally Posted by cleatus12r View Post
Rhythmic misfire? If so, it's injector time (or shimming the armature plates at a minimum).

Rough, rhythmic (as in not "hitting" on one or two cylinders) misfire without smoke until the engine is warm means non-firing injector(s). The excessive noise or rattle is because the next cylinder in the firing order is working for itself and the cylinder before it.
Uh-oh! It sounds like it is missing on one of two cylinders when it's cold. There is no smoke, but once I've gone a couple miles down the highway, it smooths out and sounds great. How do I know if this is it?
Reply With Quote
  #11  
Old 10-12-2017, 12:06 PM
Keabler's Avatar
Keabler Keabler is offline
Senior User
Thread Starter
 
Join Date: Jul 2017
Location: Yuba City
Posts: 111
Keabler is starting off with a positive reputation.
Quote:
Originally Posted by cleatus12r View Post
Rhythmic misfire? If so, it's injector time (or shimming the armature plates at a minimum).

Rough, rhythmic (as in not "hitting" on one or two cylinders) misfire without smoke until the engine is warm means non-firing injector(s). The excessive noise or rattle is because the next cylinder in the firing order is working for itself and the cylinder before it.
How does engine temp change performance of injection?
Reply With Quote
  #12  
Old 10-12-2017, 01:37 PM
jimjokjv jimjokjv is offline
Senior User
 
Join Date: Jun 2017
Location: Arizona
Posts: 148
jimjokjv is starting off with a positive reputation.
Quote:
Originally Posted by cleatus12r View Post
Rhythmic misfire? If so, it's injector time (or shimming the armature plates at a minimum).

Rough, rhythmic (as in not "hitting" on one or two cylinders) misfire without smoke until the engine is warm means non-firing injector(s). The excessive noise or rattle is because the next cylinder in the firing order is working for itself and the cylinder before it.
Would this require injector replacement?
Reply With Quote
  #13  
Old 10-12-2017, 01:42 PM
cleatus12r cleatus12r is offline
Postmaster
 
Join Date: Apr 2004
Posts: 4,641
cleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputation
Here you go....
Attached Images
 
Reply With Quote
  #14  
Old 10-12-2017, 01:43 PM
cleatus12r cleatus12r is offline
Postmaster
 
Join Date: Apr 2004
Posts: 4,641
cleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputationcleatus12r has a superb reputation
Quote:
Originally Posted by jimjokjv View Post
Would this require injector replacement?

Not always. I've successfully shimmed the armature plate on three sets of injectors and it buys a good bit of time.

Just google 7.3L injector shims and pick your poison.
Reply With Quote
  #15  
Old 10-12-2017, 02:40 PM
HD Rider's Avatar
HD Rider HD Rider is offline
Posting Guru
 
Join Date: Aug 2009
Location: Glendive, MT
Posts: 1,428
HD Rider has a great reputation on FTE.HD Rider has a great reputation on FTE.HD Rider has a great reputation on FTE.HD Rider has a great reputation on FTE.HD Rider has a great reputation on FTE.
Cold doesn't affect injector performance as much as it affects ignition. Remember the fuel in a diesel ignites spontaneously from the heat and pressure in the combustion chamber. A cold engine drawing cold air into a cold chamber injecting cold fuel will not run as nice as a warm engine.
Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
97 f150 drops into rough idle while in drive b.hope014 1997 - 2003 F150 4 05-04-2017 01:02 PM
1996 Ford F150 rough idle and miss after truck has been warmed up shawn_ziesman 1987 - 1996 F150 & Larger F-Series Trucks 1 05-02-2017 09:57 PM
rough idle eaglefire21 1994.5 - 1997 7.3L Power Stroke Diesel 25 12-05-2016 12:36 PM
Rough idle Meats12 1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks 15 05-16-2016 09:34 PM
Rough idle CBM91011 1999 to 2016 Super Duty 2 01-25-2016 08:08 PM


Go Back   Ford Truck Enthusiasts Forums >

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

Forum Jump


All times are GMT -5. The time now is 02:46 AM.