Weird misfire / no codes - Dodge Diesel - Diesel Truck Resource Forums

3rd Gen Engine and Drivetrain -> 2003-2007 5.9 liter Engine and drivetrain discussion only. PLEASE, NO HIGH PERFORMANCE DISCUSSION!

Weird misfire / no codes

Reply

 
 
 
Old 01-10-2018, 11:06 PM
  #1  
Registered User
Thread Starter
 
Adaminak's Avatar
 
Join Date: Nov 2007
Location: Charleston, SC
Posts: 616
Thanked 1 Time in 1 Post
Weird misfire / no codes

So I've been chasing an intermittent misfire for about three months now. It's been present far longer than that, but I've finally decided to do something about it. Truck has 195k miles, in-tank lift pump, II +60hp injectors that are less than 5k miles old, and a Smarty Jr.

At light throttle, with boost below 10psi and rpm between 1700 and 2000, there's a very, very slight "hitch" in propulsion. It goes away immediately when I add throttle. At first I thought it was actually suspension related, like tight shocks on a wavy road, but it's now painfully obvious that it happens on all roads, and my KYB's are no longer tight. It was present before I had new injectors, and it's present now.

I'm leaning toward a sag in rail pressure, whether it's a glitchy FCA, or a failing rail pressure sensor. Could also be a Smarty programming issue, but I've changed the tune on the Smarty, varying the torque management and timing, with no change.

I've run a quart of 2-stroke with a tank of fuel to see if it could be a sticky pump or FCA, but noticed no difference other than a stumble at first start up and a fair amount of smoke when cold. That's long since past now and it starts great, and doesn't smoke.

Not sure if it's relevant, but the truck idles fine unless I'm coasting to a stop with the tranny in neutral, in which case it hunts between 750 and 1000 rpm until I get below 10mph, when it settles out at 750.

Anybody have any thoughts?
Adaminak is offline  
Reply With Quote
Old 11-01-2018, 02:46 PM
  #2  
Registered User
 
avantidude's Avatar
 
Join Date: Feb 2007
Location: Sonora ca
Posts: 51
Thanks: 0
Thanked 4 Times in 2 Posts
What did you determine this was, I am having a similar issue.
avantidude is offline  
Reply With Quote
 
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
exwrestler
3rd Gen Engine and Drivetrain -> 2003-2007
5
02-05-2010 10:34 AM
Landini1
3rd Gen Engine and Drivetrain -> 2003-2007
1
12-25-2009 04:38 PM
sallyman1
3rd Gen High Performance and Accessories (5.9L Only)
4
08-26-2008 07:20 PM
supercharged_hp
3rd Gen High Performance and Accessories (5.9L Only)
6
03-26-2008 02:35 AM
mbenedict
HELP!
2
07-21-2007 10:19 PM


Thread Tools
Search this Thread
Quick Reply: Weird misfire / no codes


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

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.