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Hi guys

I was wondering if anyone had a suggestion for a fix on this Misfire for cylinder 5 on my 2008 Cadillac 3.6 DI performance package car with 90k miles. I replaced the coil and sparks plug already. The Check Engine light is still on. I tried swapping coils thinking maybe the new coil i got was bad. I'm about to swap spark plugs. I used a handheld Diagnostic machine from Autozone. Its small and orange. I tried to clear the code using that little hand held device by holding the red X button and it didn't work. Any help would be greatly appreciated!
 

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08 CTS DI
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Swing by Harborfreight and pick up their spark checker for about $5. You need to be sure you have fire in that cylinder and swapping the coils will not guarantee that if you don't have power to the coil on that cylinder, or if you have power and some how it is not being fired. I have the tools hanging around so I would perform a cylinder compression test to make sure I had good cylinder pressure after the parts swap, which is performed by holding the accelerator pedal to the floor while cranking for a second or two, which will prevent the motor from starting up. If the pressure is good, and the spark is there, it would most likely be a bad fuel injector. With good cylinder pressure, proper fuel and spark, it's going to fire. It's possible the engine computer could be at fault but I'd expect multiple misfires as opposed to a specific cylinder.
 

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Hey guys I’m having similar problem on my 2005 cadillac xlr compression is at 145 psi coil is new injector is good bc when I swap coil and injector it stay misfiring on cylinder 5 and when I unplug coil or injector no difference in engine trying to die
 

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2011 CTS Coupe FE3, 2003 Thunderbird, Gone 2013 ATS, 02 Deville
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You want to put this in the proper year and model Cadillac. this is CTS 2008 thru 2013
 

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Hey guys I’m having similar problem on my 2005 cadillac xlr compression is at 145 psi coil is new injector is good bc when I swap coil and injector it stay misfiring on cylinder 5 and when I unplug coil or injector no difference in engine trying to die
When you sort it out, come back and fill us in. There's another member with a chronic, intermittent misfire on a remanufactured 3.6L. He's used efforts similar to yours to try and solve it without success which makes me suspect it is a mechanical problem affecting the cylinder.
 

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08 CTS none DI 3.6
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That's me! I've changed injectors, plugs, coils, and still get the code every now and then. Freakin driving me crazy...if I do end up resolving it I'll chime in..new MAP sensor and knock sensors have been ordered.
 

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I'm very intrigued by what could be the cause of this misfire.
 

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I have similar issues with my 08 V engine with 60K miles on it. I had luck with cleaning the purge valve with electrical cleaner. it sure felt spunky after that but the car still hesitates when floored. so far it has not put out the check light for me.
my timing chain was replaced last year and think they messed up the timing as the car never ran the same again, this was done under recall, the mechanic who worked on my car didn't tighten any of the valve cover bolts and must have screwed the timing on the right bank, all the plugs on right side had large gaps.
 

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No hesitation at all with mine but purge valve? Does mine even have one of those.
EVAP purge valve, yes. Passenger side rear of engine, under the strut tower brace.

I will add that if it was malfunctioning, it should set an appropriate evap DTC like P0496 and trip the CEL, unless it's a pending code.
 
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