I have a 1999 Accord 2.3L VTEC with manual transmission which we have had for about one month. it has 160,000 miles on it and was doing just fine. it developed a miss and when I read the codes the first time it came up P0300, P0302, P0303 and P1399. I replaced the spark plugs, reset codes and still had miss but now it is P1399 and P0302. I pulled the EGR valve off cleaned it and Verified it was operating with 12 volts. tried cleaning the EGR port and was able to get a lot of junk from it but not able to really verify that the port to the intake is really clean. I replaced the distributor cap and rotor since it looked like some one had tried to clean these before. No change still the same two codes. swapped two fuel injectors no change. Jumped the number two injector to number four injector and number four injector to number two injector. Still not change. Compression test cyl 1 130, 2 140, 3 180, 4 180. no matter what I do I still get P1399 and P0302. after car reaches about 2500 RPM seems to run nice and smooth. Up to 2500 with load on motor is when you notice the miss. No able to find a leak down tester here but plan on using compressed to charge number two cylinder and see if I can find a bad valve. Open to any and all suggestions.

 

Hey menehune.

Your compression test looks suspicious: low compression between sequential cylinders #1 and #2 could be indicative of a head gasket leak. Any oily residue in the radiator neck? Any milky residue on the engine oil dipstick?

Also, seems odd your CEL results would now be a P1399 with only a P0302 - since P1399 = multiple cylinder misfires, and only cylinder #2 is reporting that its misfiring. Find the 7.5 amp radio/backup fuse (right end of the dash, open the passenger door wide), pull it for ~5 minutes to clear the CEL memory results, re-scan for codes.

What brand of spark plugs were installed? You might consider pulling the #2 plug after running the engine for at least 5 minutes to note the condition of the area including the electrode: is it dry? or wet with fuel? or with with either an oily or watery residue?

I just did an EGR port cleaning on a 2000 Accord V6 coupe, they're notorious for being plugged up but "the car's too old for Honda to apply the recall issued" against the intake's EGR port design flaw. There was a LOT of carbon buildup, and everywhere - don't exclude from a good cleaning, any portion of that end-to-end path of EGR flow.