As an update. I ordered 4 new coils from my buddy at Honda. I disconnected the battery and swapped all 4 of them. So far with a little over 40 miles the car seems perfect and no CEL. It's running very strong thus far. I am putting additional miles on the car this week and will let everyone know if it fixed the issue for good.

 

Just wanted to provide an update.

The CEL came back after swapping out the 4 new OEM coils and after hooking it up again it went from being a misfire on cylinder # 2 to misfire on multiple cylinders. The cause turned out to be bad gas. I started by checking everything in sight including the O2 sensors, sensors on the VC, vacuum hoses and everything else I could think of. I disconnected the battery (have driven for 100s of miles after) and put a bottle Techron in the tank. Drove it all the way down to the fumes and that was the last of the light. It is my understanding a case of bad gas is rare, but I guess it could happen.

 

Update: CEL is back! Misfire on all 4s and random/multiple misfires. Took it over to a buddy who connected the car to a pretty sophisticated reader. Reader showed some inconsistencies at idle. He took out the compression tester and after numerous readings came to the following numbers: 210/210/180/210. As a secondary test he dropped some oil into cylinder 3 and the compression jumped up to about 210.

This is a MY05. The car has 40,xxx miles. (Mainly street miles with 3 track days and 3 dragons.) The car was purchased at 22K. Billman's valve adjustment and TCT done at 23K (17K miles ago). The car has brand new OEM plugs and coils. The plugs look good. The oil is changed at 2000-2500 intervals - Mobil1 10w30. No drastic (wrong gear) over revs as far as I remember. The car is driven aggressively and is no stranger to the limiter.

Mods: Hytech Header, Hytech 70mm Test Pipe, 70mm Single Exhaust, Toda Flywheel, ACT Pressure Plate, OEM intake with K&N filter.

Off to Billman for a full check up at the end of the month. Praying for the best.

 

 

This is MY00, I had P1339 and P0301 2 years ago and I replaced the ignition coils made by Denso for AP2 and it worked fine for 2 years, but now those codes came back even tho the car is running perfect with No Issues at all, so I decided to replaced the spark plugs and still getting same codes. Should I replace the OEM ignition coils for AP1?

 

You should determine the issue (through substitution if necessary) before just buying replacements of everything one by one.

 

 

I even swapped the coils to diff. location and it threw more codes P1339, P0301, P0302, P0303

 

 

Found the cause of my CEL P1399. It was the generic coils I put in last year. I bought them online. They came in a individual brown cardboard boxes with part number 1AECI00198 (Made in China) on the boxes. They only lasted about a year and maybe 2000 miles. I drive the S very seldom. At idle it was misfiring and you could really feel it when you would try to accelerate. I thought it might have been bad fuel, so I put a bottle of Iso Heet in the tank but saw no change. Checked the spark plugs for condition and gap (all were fine). Just intalled them last year. My car has 78K miles. I ajusted the valves recentlly but I check them anyway (they were fine also). After putting everthing back together and starting the car, it still had the misfire. Decided to change the coils to factory ones. Started the car and no misfire! Took the S for a drive today and it is running great!

Thanks for this thread, it helped me find the problem,

Glenn

'04 Rio Yellow Pearl