2011 Ram 1500 4x4, 5.7L/545RFE, 131,xxx miles.
*All 16 spark plugs, #3 ignition coil, #3 fuel injector, & Intake manifold seal changed in an attempt to fix DTC P0303.
*Customer complaint.....Misfires randomly/intermittently.
*Requested a Vacuum "check" because he read on the internet that valvetrain issues would result in erratic Manifold Vacuum.
Couldn't really argue with that....Broken valve springs & sticky/stuck valves can certainly cause timed drops in manifold vacuum. Don't usually get caught-up in other peoples diagnostic process because I have my own & adhering to it keeps me focused. Guy was nice enough & gaining new customers is important to my fledgling business, So I decided to oblige him & do the test while he waited.
Engine was actively misfiring at first but slowly cleared up while performing the vacuum test.....Steady 18 inches of vacuum the whole time.
I commented about the noticeably audible valve/lifter tick & the fact these (MDS 5.7L's) are notorious for wiping out camshaft lobes & lifters. Recommended that the valve cover be removed for a visual inspection.
That's when the whole story gets spilled.....He has paid 3 different shops to diagnose & throw parts at this & is understandably reluctant to throw money at yet another misdiagnoses....And stated that the tick has been there for years.
I said....."Tell you what.....I'll pull the valve cover right now while you wait, If I don't find an/the issue, I'll reinstall the valve cover & you don't own me anything"
Took about 10 minutes to pull the driver side/bank 1 cover & Set my scanners bi-directional controls to activate the starter relay. Then I got my flashlight positioned so he could watch the valve action with me.
#3 intake valve was moving @ 0.030" while #5 intake valve was moving over .500"...... He was
Also asked a very good question that I honestly didn't have an answer for....."Why is the misfire intermittent"
Video of the vacuum test....Hear the tick?
*All 16 spark plugs, #3 ignition coil, #3 fuel injector, & Intake manifold seal changed in an attempt to fix DTC P0303.
*Customer complaint.....Misfires randomly/intermittently.
*Requested a Vacuum "check" because he read on the internet that valvetrain issues would result in erratic Manifold Vacuum.
Couldn't really argue with that....Broken valve springs & sticky/stuck valves can certainly cause timed drops in manifold vacuum. Don't usually get caught-up in other peoples diagnostic process because I have my own & adhering to it keeps me focused. Guy was nice enough & gaining new customers is important to my fledgling business, So I decided to oblige him & do the test while he waited.
Engine was actively misfiring at first but slowly cleared up while performing the vacuum test.....Steady 18 inches of vacuum the whole time.
I commented about the noticeably audible valve/lifter tick & the fact these (MDS 5.7L's) are notorious for wiping out camshaft lobes & lifters. Recommended that the valve cover be removed for a visual inspection.
That's when the whole story gets spilled.....He has paid 3 different shops to diagnose & throw parts at this & is understandably reluctant to throw money at yet another misdiagnoses....And stated that the tick has been there for years.
I said....."Tell you what.....I'll pull the valve cover right now while you wait, If I don't find an/the issue, I'll reinstall the valve cover & you don't own me anything"
Took about 10 minutes to pull the driver side/bank 1 cover & Set my scanners bi-directional controls to activate the starter relay. Then I got my flashlight positioned so he could watch the valve action with me.
#3 intake valve was moving @ 0.030" while #5 intake valve was moving over .500"...... He was
Video of the vacuum test....Hear the tick?