2009 Ram 1500 5.7 MDS - weird #5 misfire problem
#1
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2009 Ram 1500 5.7 MDS - weird #5 misfire problem
(I posted this on Ram Forum as well so please ignore if you've already seen it.)
I have a weird thing happening at 135K miles, with a clean well-maintained, original-owner 2009 Ram 1500 Hemi MDS. It’s actually two things that are probably related:
I have a weird thing happening at 135K miles, with a clean well-maintained, original-owner 2009 Ram 1500 Hemi MDS. It’s actually two things that are probably related:
- After a cold start, it runs fine. I drive about 1 minute and if/when it kicks into eco/MDS mode, it runs poorly (95% sure due to cyl #5 - see below) until I either pull over and turn off the ignition completely, and restart, or until it warms up over ~165F or higher. This NEVER happens if I start out in Tow/Haul mode or with shifter in a lower gear i.e. 5th, in order to keep it from going into eco/MDS mode until warmed up (or over 165F). Once it’s warmed up, I can use eco/MDS mode just fine, and it purrs along great – like new,
- BUT under normal operating temp, if I put relatively heavy throttle into it, typically on the highway, somewhere between 3-4K RPM, it throws a P0305 #5 cyl misfire code. When I let up, the light usually goes away pretty quickly. But this will repeat fairly consistently under heavier throttle, and when it’s occurring, I can usually feel the roughness until it clears.
#3
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In condition 2, I tend to get the misfire code regardless of tow/haul being on or off, under higher RPMs/acceleration. If I never put my foot into it, day to day, I never get the misfire described in 2. But I also feel like (and hope) it's computer related.
#4
Mopar Lover
Couple things you mite look at with a scan tool....
1. Make sure the system is inactive when you mash the throttle
2. Take a look at the injector pulse width and see if is different than the rest.
3. Looks at that cylinder and compare it with the other cylinders on a lab scope parade patten.
1. Make sure the system is inactive when you mash the throttle
2. Take a look at the injector pulse width and see if is different than the rest.
3. Looks at that cylinder and compare it with the other cylinders on a lab scope parade patten.
Last edited by RacerHog; 05-01-2024 at 06:42 PM.
#5
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Also, the fact that shutting off the ignition all the way before starting it back up, seems to make it run smoothly again points me back to the computer/PCM.
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