BACK FIRE AND CYLINDER MISFIRE

2007 Dodge Ram

Tiny

Schirico

December, 30, 2011 AT 4:28 AM

2007 hemi pick up. I keep having a back fire. One tech said it's a miss fire on cylinder 6&7. I changed all 16 plugs. Still problem. Changed coils on 6, 7&8. Changed the cam or crank sensor (the one right below the alternator). Still having problems. No codes are being thrown on the computer. Help please

FOUND 1244 RELATED QUESTIONS

8 Answers

Tiny

fixitmr

December, 30, 2011 AT 6:15 AM

Is the backfire intake or exhaust?

Tiny

Schirico

December, 31, 2011 AT 4:58 AM

Exhaust

Tiny

fixitmr

December, 31, 2011 AT 7:15 AM

Backfire thru exhaust confirms misfire. So how did old plugs look? Especially 6-7. And does your motor have MDS?

Tiny

fixitmr

December, 31, 2011 AT 7:17 AM

You could try switching injectors on 6-7 with nextdoor cylinders and see if problem moves with them?

Tiny

Schirico

December, 31, 2011 AT 2:56 PM

The old plugs looked good. Don't know what MDS means. Do injectors get bad or do the clog up.

Tiny

fixitmr

January, 1, 2012 AT 5:59 AM

MDS is gas saving 4cyl operation when cruisin. Injectors do both.

Tiny

Schirico

January, 1, 2012 AT 11:04 PM

Yes. And I notice the backfire when I let off the gas pedal

Tiny

fixitmr

January, 2, 2012 AT 4:39 AM

I would say MDS takes this diagnosis beyond do it yourself. VVT adds extra complications to any attemp to guess at fix. You will have to take it in to get diagnosed with the right equipment and procedures.

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