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Cyl 1 misfire already replaced coils, plug connectors..acceleration…

99 996 code reading po301...
99 996 code reading po301 cyl 1 misfire
already replaced coils, plug connectors, plugs
cel light comes on upon moderate acceleration
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Answered in 22 hours by:
6/30/2010
Sebastian Vizcarra
Sebastian Vizcarra, Porsche Meister Tech
Category: Porsche
Satisfied Customers: 422
Experience: Porsche Factory Certified Master Technician
Verified
The problem could be from the dual mass flywheel to the lifters. To properly diagnose from here on forward, you would need to verify the mechanical integrity of the engine with a compression test and leak down test. Then to test the flywheel requires the removal of the transmission. This only applies to manual trans though.

If you have an automatic, then its most likely your lifters, but you would need to determine which side of engine, as the P code is not 100% in indicating the correct cylinder that is actually misfiring.

Sebastian V.
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Customer reply replied 8 years ago

short ot that is there any other thing I can try to determine that the number one cyl is recieving spark or the rest of the cyls for that matter

You would need at least a scan tool to determine which cylinder bank is misfiring, you would look at lets say bank 1 upstream oxygen sensor before catalytic converter. What you would see if you had a misfire is the sensor voltage hanging either high or lower than normal than the opposite bank. Short of that, you need specialized test equipment to verify 100% what is causing your misfire.


Sebastian V.
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Customer reply replied 8 years ago

you mentioned oxygen sensor , as a matter of fact I repaced the sensor on bank one before cc as per obd code ,prior to that when light would come on it would misfire and actually turn off , now there is no noticeable misfire nor does it turn off when light comes on

The code was probably for Oxygen sensing below or above limit. This didn't mean the o2 was bad but that the fuel mixture control was at its rich or lean limit of adjustment. This can happen when you have a misfire caused by an internal engine part failure or an external component such as a coil.

If the check engine light starts to flash you need to turn off your engine, or the cat converter will melt and get plugged up.

Try and remove the Mass air flow sensor and clean it with CRC electronics cleaner, this is available at Home depot or your local parts store. This is something easy to do. Other than that, specific tests need to be done along with the help of data.

Sebastian V.
Sebastian Vizcarra
Sebastian Vizcarra, Porsche Meister Tech
Category: Porsche
Satisfied Customers: 422
Experience: Porsche Factory Certified Master Technician
Verified
Sebastian Vizcarra and 87 other Porsche Specialists are ready to help you
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Customer reply replied 8 years ago

will try that thank you for your input very helpful

No problem, let me know how it goes.
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