Missfire (code 0300) @ WOT
Thread Starter
Racer
Joined: Dec 2006
Posts: 279
Likes: 0
From: Salinas Ca
Missfire (code 0300) @ WOT
Had a dyno tune a few months ago. Car ran great till lately, but now it missfires noticeably when I go wide open throttle. It will cruise fine all day long after I clear the code without resetting a code. Any ideas on where to look first?
Car is a '03 A4 with vararam, machined throttle body, magnaflow cat backs, and 3.42 gears.
Car is a '03 A4 with vararam, machined throttle body, magnaflow cat backs, and 3.42 gears.
Last edited by hangpilot; Sep 1, 2008 at 06:06 PM.
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
WOT is the highest cylinder pressure your cylinders will see. Cylinder pressure puts out sparks and requires the highest voltage to achieve spark. Pull your plugs and check the gap. Should be using NGk TR55's or 6's gap to .040" or no tighter than .035". Pull your wires and put an ohm meter across each one. make sure they're all equal resistance. The bad one will jump out at you. You can't test the coils because they have active components in them. If you have HPtuners, you can log the car and isolate the problem to one side by possibly watching your 02's react to the misfire.
You can do a WOT run and then shut the car down and pull the plugs in inspect each one to help identify which cylinder is causing your problem. Could also be one of your cats starting to become a restriction.
You can do a WOT run and then shut the car down and pull the plugs in inspect each one to help identify which cylinder is causing your problem. Could also be one of your cats starting to become a restriction.
, Have you checked the plug wires?
Thread Starter
Racer
Joined: Dec 2006
Posts: 279
Likes: 0
From: Salinas Ca
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Can you actually hear or feel the misfire??If not than you may be getting some false misfire triggers and would need to desensitise the KR table PO300 is a very common code for hd/cam installs--also a clod air kit like varram could cause a false triggerIg=F you can HEAR or FEEL them --thats different--make sure ther mods are securly tightened Too many misfires will make an A4 shift horribly
