2014 Ram 1500 5.7 Hemi Misfires, Lean code, Stalling, need advice!

[BrodyTampa]

Hey everyone, love this forum and all the helpful people. This is my first time asking for advice. I apologize for the lengthy post but I’m not sure where to turn next.


2014 Ram 1500 Sport, 5.7 HEMI, approximately 120,000 miles.


I’ve been chasing an intermittent misfire that has progressively gotten worse over the past three weeks. Had a mobile mechanic spend five hours diagnosing it yesterday, but still haven’t identified the cause.


Code History:

• P1417 – Cylinder 7 reactivation control performance (MDS).
• P0307 – Cylinder 7 misfire.
• P0300 – Random/multiple cylinder misfire.
• P0171 – System too lean (Bank 1).

Timeline:


October 3: First experienced rough idle and misfires after clearing codes while troubleshooting an EVAP issue. Initially P1417 and P0307. Truck would sometimes run rough, hesitate, or surge slightly, but a restart made it run normally again. Then next start rough again.

Truck sat:

October 16: Replaced all 16 spark plugs with NGK 92145 from RockAuto, torqued to 13ft/lb. Came pre-gapped and same as originals I took out. Truck initially ran smoothly but began misfiring again within minutes. P0300 and P0171 appeared with the check engine light flashing.

Truck sat:


October 25 – Mobile Mechanic Diagnostics:

Mechanic spent approximately five hours investigating.

• Scanner showed heavy misfires on nearly every cylinder, with only two cylinders not registering significant misfires.
• Found a broken engine ground strap. Bypassed with jumper cables, no improvement.
• Smoke-tested intake/vacuum system. No obvious leaks found.
• Tested ignition/spark using coils and spark plugs.
• Found some “loose spark plugs” and tightened them. No improvement.
• Investigated exhaust manifold leaks and removed oxygen sensors, but did not restart the engine with sensors removed. Said catalytic converters look ok
• Reported fuel pressure was good, but I don’t have an actual pressure reading.
• Probed PCM connections and reported apparently weak signals to the fuel injectors.
• Mentioned a possible crankshaft keyway/timing issue, but nothing confirmed.
• Sprayed starter fluid into the intake. Engine ran noticeably better and stayed running while spraying, but stalled almost immediately when he stopped.
• Returned Superchips 87-octane tune to factory stock. No improvement.

Additional Information:

• Previously replaced ESIM, gas cap, and purge valve while troubleshooting EVAP issues.
• Both exhaust manifolds have broken bolts and have ticked on cold starts for years.
• No noticeable lifter tick.
• Engine oil is Pennzoil Ultra Platinum 5W-20.
• The truck originally had intermittent misfires but could drive normally after restarting. Now it runs extremely rough and frequently stalls.
• ABS module has been broken for a few years

Up until now the truck has run strong and no noticeable knocking noises.

Looking for advice:

The biggest clue seems to be that starter fluid temporarily keeps the engine running. I’m wondering about fuel delivery, injector control, PCM, or an electrical/ground issue, or mechanical?


Has anyone experienced similar symptoms on a 5.7 HEMI? What would you test next before replacing expensive components?


I’d appreciate any suggestions!

 

[Burla]

He spent 5 hours no leak down or compression testing? Cam lob on 7 likely wiped. That's how most cams fail on the board, starts out here and there, and before you know it it wont be touching lifter at all.

 

[BrodyTampa]

Yeah 5 hours, I had to suggest a fuel pressure check, mds solenoid activation test.. he just kept starting it until it wouldn’t stay running anymore. Do you think there’s chance of gas contamination in the oil? I smelled the dipstick oil it didn’t smell like gas. Just wondering if 40-50 crank and stalls could make things worse.

 

[hunterdan]

The mds solenoids can fail, and the reactivation code could be a sign of that. I would start simple and pull injectors and test them to make sure they're firing cleanly and evenly. If they're gummed up or partially clogged could be causing intermittent misfires. Then run the compression and leak down tests.

 

[BrodyTampa]

Could these broken grounds that were found cause anything crazy like the misfires?

 

[GeauxinUp]

October 3: First experienced rough idle and misfires after clearing codes while troubleshooting an EVAP issue. Initially P1417 and P0307. Truck would sometimes run rough, hesitate, or surge slightly, but a restart made it run normally again. Then next start rough again.

So, I'm assuming everything was fine before Oct 3, when you were doing your EVAP diagnosis? What exactly did you do to fix/clear the EVAP codes?

 

[BrodyTampa]

Yes truck was running just fine. Just had the evap codes. I replaced the gas cap and the esim (check gas cap light went away) and also the purge valve. All of those codes went from current to permanent besides a small leak code. Was waiting for the evap test to run by itself to see if the cel would turn off. Since I was only driving a mile here and there I don’t think the test had the right conditions to run and would be INC. I got a little impatient. I plugged my scanner in and cleared codes. Then the very first start a min after got the misfire feel. Mds performance code and the cylinder 7 misfire code. Drove the truck for a mile. It felt like maybe limp mode. Drove home. Shut it off. Started again a few mins later and all was smooth, took for a short test drive and it felt good. The next day and subsequent starts it had the one cylinder misfire feel but not as bad as limp mode feel. Parked the truck until new plugs arrived. Installed them. Then got the p0300 random/multiple misfires. And a blinking check engine.

 

[GeauxinUp]

Yes truck was running just fine. Just had the evap codes. I replaced the gas cap and the esim (check gas cap light went away) and also the purge valve. All of those codes went from current to permanent besides a small leak code. Was waiting for the evap test to run by itself to see if the cel would turn off. Since I was only driving a mile here and there I don’t think the test had the right conditions to run and would be INC. I got a little impatient. I plugged my scanner in and cleared codes. Then the very first start a min after got the misfire feel. Mds performance code and the cylinder 7 misfire code. Drove the truck for a mile. It felt like maybe limp mode. Drove home. Shut it off. Started again a few mins later and all was smooth, took for a short test drive and it felt good. The next day and subsequent starts it had the one cylinder misfire feel but not as bad as limp mode feel. Parked the truck until new plugs arrived. Installed them. Then got the p0300 random/multiple misfires. And a blinking check engine.

Just a theory here, but makes sense that maybe something happened while swapping the purge valve. My thoughts are that it's either defective, improper install, or you knocked something lose. I'm thinking you may have a vacuum leak somewhere.

Disconnect your purge valve (with the engine off) and see if it allows airflow through it, it should be closed without power.

I'd also inspect all the vacuum connections around the purge valve and intake manifold. You could cap the manifold vacuum port for the purge valve (temporarily) and see if the engine smooths out. If it does, then that would mean you're probably on the right track. Do you have a scanner capable of reading live data (short and long term fuel trims)?
I'd definitely try to rule all that out before throwing more parts at it. Also, I ain't saying this would be the cause of your cyl 7 misfire, but I'd clear all the lean stuff up before pursuing other trouble.