Random Misfires I have a 99 acura tl. I got it checked out and it seems all 6 cylinders are missing. I changed spark plugs, coils, full tune up. cannot seem to figure it out would like some ideas on what it could be. Both tcs and check engine light are on. had convertor replaced. egr ports cleaned.

This is Coil On Plug ignition. yes?

Are you getting cylinder 4 misfires?.

Reinstall plug and COP but leave cable disconnected to coil. If its seems to start ok with only the COP disconnected I would suspect noise is being fed back from the COP and disruptIng ignition for the other cylinders.

If you replace the COP don't go cheap... pay the premium for the OEM part.

First you need to determine what type of miss you have. Is it random on all cylinders, or is it restricted to one or two cylinders? Random misfire can be caused by crank or cam sensors that are starting to give out. Single cylinder misfires can be due to plugs, wires, coils (you already addressed those), as well as internal issues such as burnt or broken valves.

PO300 and P1399 are random cylinder misfire detected.
PO301 cylinder 1 misfire
PO302 cylinder 2 misfire
PO304 cylinder 4 misfire
PO306 cylinder 6 misfire
I would say that you have damage to the ignition wiring harness or you ECM is failing.

its faulty coil.

Get the compression test done on each coil.these will let you know if its faulty coil or not.

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It can be issue with spark plugs or faulty spark plugs. Also get the compression test done for cylinders. If any of cylinder shows low compression then required, then that particular cylinder will cause misfire.

Also get obd codes scanned, the error code will let you know which cylinder is misfiring or all cylinders are misfiring.

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For your trouble shooting I suggest you to refer the help oinks below. It has step by step details for many engine misfire issues.

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Click the link below:-----

Ford Explorer Cylinder Misfire?

http://whoisbyme.blogspot.in/2012/06/ford-explorer-cylinder-misfire.html

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Engine Misfire codes on Chevrolet Malibu?

http://schematicsdiagram.blogspot.com/2011/12/engine-misfire-codes-on-chevrolet.html

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Cylinder 6 Misfire?

http://howtobyme.blogspot.com/2011/12/cylinder-6-misfire.html

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Misfire on cylinder 4?

http://schematicsdiagram.blogspot.com/2011/12/misfire-on-cylinder-4.html

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While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

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Ford Explorer 5.0L: Engine Miss?

http://whoisbyme.blogspot.in/2012/06/ford-explorer-50l-engine-miss.html

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Oil on spark plugs and car misfires?

http://technoanswers.blogspot.in/2012/02/oil-on-spark-plugs-and-car-misfires.html

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Can cylinder misfire Damage the Catalytic converter?

http://schematicsdiagram.blogspot.in/2012/02/can-cylinder-misfire-damage-catalytic.html

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Car misfires and error code P0306 and P0303 is shown?

http://technoanswers.blogspot.com/2012/01/car-misfires-and-error-code-p0306-and.html

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Chevrolet K1500 No spark, random misfire

http://repairhelpcenter.blogspot.com/2012/11/chevrolet-k1500-no-sparkrandom-misfire.html

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2004 Ford F150: Engine Misfire and Lean Code?

http://whatisbyme.blogspot.in/2012/05/2004-ford-f150-engine-misfire-and-lean.html

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1995 Toyota LS: Misfire at idle or low RPM

http://whatisbyme.blogspot.in/2012/04/1995-toyota-ls-misfire-at-idle-or-low.html

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Toyota Corolla: Random Misfire?

http://technoanswers.blogspot.in/2012/04/toyota-corolla-random-misfire.html

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2006 Ford Freestar: Misfire on Cylinder Number 2?

http://whatisbyme.blogspot.in/2012/06/2006-ford-freestar-misfire-on-cylinder.html

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This will help.

Thanks.

Check and test injection system. 300 is misfirn random and 306 mifrie cyl #6

Misfires are caused by fuel delivery problems, injectors or too rich or weak. Spark issues, coil, wires, spark plugs or the cap and roter.
I could also be a loss of compression. First thing to check is the easiest... spark plugs, spark and cap and roter. Also the cheapest.

REPLACE DISTRIBUTOR CAP AND ROTOR REPLACE SPARK PLUGS AND WIRES IF NOT BEEN CHANGED IN LONG PERIOD OF TIME.CHECK IGNITION TIMING.CHANGE AIR FILTER CLEAN FUEL INJECTORS.IF ENGINE STILL MISFIRE IGNITION COIL IS WEAK OR YOU HAVE LOW CYLINDER COMPRESSION.

Instead of the auto-zone trip , take it to the dealer !

See if your car has an ignition control module. They will go bad over time and cause random engine misfiring. Just went thru it with my 2002 Buick LeSabre. 120,000 miles on the engine. Replaced plugs, plug wires and check the coils. It was the ICM.

if you have a coil on plug system, or a waste spark system.... swap coils and see if the miss follows the coil.... voila... that'll fix it.