Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!

2011 QX56 5.6l Multiple missfires

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3 years 1 month ago #47654 by Richard1
Multiple missfire but mostly on Cylinder #2 by far.
Also a 087 Low fuel pressure, however my scanner shows while test driving the Fuel Rail pressure is mostly higher then PCM request by 50lbs to 100lbs or more
This High pressure fuel pump is around $1000 or so, hate to replace it if its a injector problem which are under the intake ouff.

Coil 2 was switched problem remains on #2
Plug 2 was switched problem remains on #2
Compression tester on order should have it this week,

Miss fire on start and low rpm at High rpm seems to be much better no lack of power.
LTFR both banks under 10 combined

Any suggestion so I dont replace unneeded parts, any help is appreciated, very few qualified mechanics in Panama. Dealer suggest replace the pump sure........

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3 years 1 month ago #47664 by Cheryl
Does fuel pressure hold with key off? If not you could use borescope in cylinder.

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3 years 1 month ago #47665 by Richard1
It does not, in the morning I turn the ignition on and I can hear the pump run for at least 30 sec before it stops. I'm guessing I hear the low pressure one in the tank and not the mecanical high pressure one.

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3 years 1 month ago #47666 by Cheryl
So the fuel pressure does not hold? There’s your problem

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3 years 1 month ago #47677 by Richard1
Hi Cheryl
Thank you for your help
What would you look for with the borescope?

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3 years 1 month ago #47691 by Tutti57
I believe Cheryl is talking about looking in the cylinder for fuel leaking in, if you're finding the pressure bleeding down quickly.

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