Like the title says, its a 2000 integra ls with 208,000mi.
Keep getting a p1399 code, and only that code. Seems like an off balance type misfire, ive had the p0300 misfire it is much more stout.
Ive read up on this and found a TON of diff causes. What is the diff between p0300 and p1399? What should i start by checking? Plugs and wires are less than a year old, cap and rotor too. Replaced coil a few years ago. Like i said it doesnt feel like an ign misfire.
Egr? Fuel filter? Valves? Please any advise would help.

 

Do a pulse test on the injectors then check the signal at the ECU look up an obd2 pinout sheet you'll need a test light also. Ill tell you how those codes work p1399(the 3rd number tells you what cyl it's in) but with p0300 it's RANDOM so could be 1-4. if you feel it's the valves do a comp test wet/dry then leakdown i'd say do a comp test first simpler than trying to catch a radom missfire with a test light/noid

 

Ill check the injectors i suppose. You said the 3rd number is the cyl so with a p1399 is cyl 9???? I know with the P030(0 is random 1-4 are cyl numbers). Not getting p0300 which is why an ign misfire seems even more odd. I have seen p0300 on this car years ago and plugs and wires fixed it, acted much differently. I'm leanin towards a fuel issue but that could be any number of things. The injectors are not original, did them at somewhere around 100k so it's possible. Will an ohms test be good enough?

 

3rd number=3 sorry i counted the p as a number.

but if you're only getting p1399 comp test cyl #3 wet and dry test.