[papajohn]

2014 RT max with AWD. 5.7 liter Hemi engine.

Been having issues now for the last month and a half that I've been trying to work on with the dealer. When the engine is fully warmed up I will start experiencing backfiring out of the intake. Specifically cruising along steady speed not accelerating. More pronounced steady climb up a hill, but does it on a level surface as well. No CEL to give the dealer a clue. I use mid grade 89 octane as recommended for this engine.

Dealer thus far has done a "tune up" changing all the plugs out and did a fuel system cleaning. They recommended trying different gas brands no change.

After the dealer performed the work the frequency of backfire has subsided, but is now more pronounced when it happens.

Car currently has approximately 34.5k miles.

Any ideas?


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[Matthew Nichols]

Did they do any type of onboard data logging and reproduce the conditions leading up the the backfire?

If data logging didn't help, I would try and narrow down where the "backfire" was coming from. I would start with the intake manifold and make sure all bolts were tight, looking for cracks or discoloration on and around the manifold, I would then make sure all manifold bolts were torqued to spec. Then I would go to the spark plugs, remove and closely examine all spark plugs. Look for anything that is out of the ordinary and keep track of what cylinder they came from. Look for cracks, fouling, bad threads, anything that doesn't look normal. Use your multi-meter set to Ohms and measure the resistance of your ignition coils, make sure they are all the same or very close. If all that is good, I would remove the intake manifold and closely examine the manifold gaskets and the mating surfaces the gaskets seal to. Look for any type of damage, anything that doesn't look right.

I would then remove engine sensors and test when they are cold and again when they are hot. Sometimes a bad reading will only show up when they're hot.

While you're doing all this, look for any wires/wire connectors that are burned, blackened, crimped or broken.

 

[krautmaster]

Try turning off the MDS before you do anything else. Also, when old carburetor cars backfired through the intake it was always a timing issue.

 

[Hockeydad2000]

I also have a 2014 Dodge Charger R/T max 5.7 Hemi that is backfiring through the intake. But mine has 118K miles. Replaced the air temperature and MAP sensors but no change. The problem mostly occurs at low temperatures, usually between 1500-2500 rpm, and only on deceleration. Not using the MDS did not make a difference. Papajohn, did you find out the issue with your Charger?

 

[N8ECH]

HD:
Verify that your intake manifold bolts are torqued correctly. They have been known to loosen up over time. If they are ok, verify that fuel pressure is what is should be, and up to snuff under load.

Don

 

[Hockeydad2000]

Thanks Don for the advice! I will have this checked.

 

[SRT-8Charger]

Back firing through the intake is a timing issue or a burnt intake valve. Check to make sure that the coil pack is not carbon tracking down the side of the sparkplug. Changing plugs only won't fix this as the carbon gets transferred to the plug boot as well. You either have to change the boot and the plug out or clean the boot and change the plug out.
On the burnt intake valve, this could be an MDS problem or a caused problem. You need to do a compression test on all cylinders to verify they are all at 150psi plus. Any weak ones could be the problem. There have also been some known lifter and broken spring problems. It would be worth pulling the valve covers and checking function of all valves and tightness of the pushrod. An MDS lifter could have failed.