'99 Civic Ex D16Y8 misfire: P1399, P0300, P0301
 

I have searched countless forums and have not found a solution. I apologise that this will be a large post, but I will try to be clear on what has been done and what the issue is now... :o This one has me embarrassed.
The crazy misfire problem…
I have a 1999 Honda Civic EX, D16Y8 motor M/T, VTEC, no EGR. 194,000 miles

I have had the P1399 and P0301 error code come up a few months ago. I changed; cap, rotor, plugs, and wires and the problem went away for a month. The code would come up again while at idle then while driving a lot of highway miles the CEL would then go off.
Fast forward a few months, I now have P1399, P0300, P0301, and sometimes with P0303. A little history, I had my IACV clogged up about a year ago, I cleaned it and it worked fine then. Also, when I started getting the CEL again (where I am now) I was looking over my plug wires and noticed that the timing for #1 and I think #3 were in the wrong position. I am pretty sure I did one for one swap like 100k miles ago, but not sure. Well it ran fine like that, I’m not sure how. Could this mistake have caused other damage, e.g. carbon buildup, or pre detonation and ruin my valve seats?? Any how I now have this misfire problem and… So far I have:
-Checked for any possible air leaks… nothing noted, used brake cleaner
-Checked coolant temp sensor (Ohm check good, changed anyway)
-Checked TPS (volt check good)
-Checked Crank position sensor (Ohm check good, changed anyway with used one)
-Checked fuel pressure test (Actron CP7838 tester) about 2 psi under normal, don’t know if it is a problem with the $45 tester or not. Did this check again after new Fram fuel filter and Delphi fuel pump(FE0169)… same results.
-Checked fuel pressure regulator (drops 10 pressure as designed w/ vac tube on)
-Checked the coil (ohm check good, changed anyway)
-Checked spark (good, gap is good too), pulled wires while running and results in poor idle for each cylinder
-Checked each injector plug by pulling it while running, results in poor idle for each cylinder also
-Checked each injector plug with LED (all operational)
-Checked each fuel injector, all 13 ohms, then checked operation with engine off and applying power, fuel pressure dropped evenly for each injector
-Checked compression dry #1 180psi #2 165 psi #3 165psi #4 180 psi
-Checked psi for 2 min after compression check, each cylinder holds pressure
-Checked timing with SRS jumper wire in place, on red mark
-Checked VTEC solenoid (ohm check and operation good) changed anyway
-Checked speed sensor, 0-5 volts cycled on and off with tire rotating
-Checked PCV and it works now after I changed it
-Checked catalytic converter, no crud of buildup at all and I can see through it fine
-Checked my valve clearance a few times. I recently gave my valves extra clearance to the point it’s ticking .010 intake .012 exhaust. I will move back to spec Intake .008 and Exhaust .010.

What I have done, and what I have changed:
-Ran SeaFoam (2x) and Lucas Fuel Injector Cleaner
-Sparkplugs -> NGK spec, gap is set good
-Changed cap and plug wires -> Honda OEM
-Changed Fuel filter -> Fram
-Changed fuel pump -> Delphi FE0169
-MAP sensor from junkyard
-Changed both O2 sensors
-New battery (this helped the most, but problem came back)
-Changed PCV
-Changed VTEC solenoid (still operational)
-Changed timing belt and water pump
-Changed #1 cyl fuel injector (no change and all are working fine I think)
-Changed intake manifold gasket for tight seal
-Changed knock sensor (broke doing intake gasket :eek: $140 mistake)
-Cleaned IACV
-Looked for intake leaks all round manifold and hoses using brake cleaner and nothing was found. I think I hear a leak around IACV but not sure and does not change idle when I spar cleaner around it.
-Swapped distributor with one from Honda dismantler and same problem existed
-Even changed the EVAP control solenoid, thought maybe the vacuum leak could be from there, but there was not.

So what I am seeing/feeling… with the valves where they should be and everything together I hear the problem through the tail pipe, I hear a sputter every second or two, like it misfires every few rpm. The misfire adjusts and is random (like the CEL says), like the fuel is being trimmed to try compensating. I can also feel the engine running rough and shaking through the steering wheel. Both of these are more noticeable when warm. The misfire cannot be felt when on the freeway, and it seems to be fine once the freeway, and NO loss in MPG either, and still has decent power on the freeway.
After I shut the car off and take it out again when cold I feel the motor bog down and drop in RPM two times, but that is it... then it clears up. I know that is odd but what I have noticed. Feels like the motor is being flooded or something. I can push in the clutch and reav it up a few times just fine and resume driving. The bogging down only happens two times a cycle and mostly when the car is not @ running temp yet.

I am using a cheap little OBDII MaxiScan MS300 tool to read my codes, and clear them after I attempt to fix the problem. The same CEL codes coming up. I’m not sure where I should go from here. I don’t want to put ideas out there and lead everyone in a direction, but could it be possible my head is cracked even though I don’t lose compression. Or could the problem be that my valves are not seating all the way? Could the problem be from having the wrong firing order for a while and resulting in the head, or valves being damaged? I am bout to change the head out if it might be damaged. I want to avoid having to send mine to a machine shop and costing me $300 vs. $100 for a good used head. Or could it be a bad IACV now? This might be irrelevant, but my cruise control stopped working about the same time my CEL came on. With that said… please let me know what you think I should do next, thank you much!!

about compression
 

I was told by a honda mechanic that the compression for this engine is 185 which leads me to believe that cylinders 2 and 3 are low, which could be your problem. although valve adjustment and bad timing could affect this. might be worth taking a look at

I'm going through the exact same thing right now with my 97 civic y8. I just rebuilt the motor, and its driving me crazy trying to figure it out. I did basically everything you did. Including replacing cap/Toyota, swapped dist, swapped/cleaned iacv, swapped throttle bodies, checked valve lash, tripple checked timing and belt tension, I lapped my valves, swapped plugs and wires.

I have not yet checked my cat, fuel pressure or checked my cylinder pressure since the 1000 miles on the rebuild. Have you had any luck figuring this out? I'm also not throwing any codes or noting worse gas mileage.

Edit- Cap/rotor

Update to OP. Swapped all new injectors, fuel rail, pressure Reg. Still no change

Checked compression dry I've got 190,185,185,194. Also gapped plugs. One question to the OP, you said you've changed cap and wires, as have I. But did you change the rotor because I haven't. Also the ECT sensor closest to the rad hose on the head. It controls fuel/air according to temp. Thos is my next step.

Thanks for the tip Realdeal_civic_00, I have my head off right now, and debating if I really want to tear into the bottom end :-/. Would that be risky?
Good question, I did change my rotor a while ago but didn't do that again recently but maybe I should, although it did read good ohms. Yes, the ECT sensor is the one on the head that you're talking about. I wouldn't recommend changing it if it has a good ohm reading, after all, it was just a waste of money for me. Damn this misfire is one pain in the butt. Let me know how if you make any progress please!

So my update; A week and a half ago I reset my valves to be pretty darn loose, like .03 over spec… my valves were ticking soooo badly! I drove it this way to work and back ~20 miles total, and of course the CEL came on again w/ the same codes. The following morning I adjusted the valves back to spec. I also messed with the IACV, unplugging it and making sure it was getting a signal etc. The IACV works but I am not sure that it works correctly. But back to the valves… I put everything back together again, all adjustments set, then drove it a few miles and the CEL stayed off! I drove it some more, around town etc and still no light. I was in shock. After a few start and stops, on and off, I took it to the SMOG shop. It passed (with Nox at the limit) however the problem is that the ECM had not run enough miles, sucks!! So I drove it anther 200 miles as the shop suggested, and that was still was not enough for the SMOG shop computer. Then over time and after driving it 275 miles, the CEL came back on:(, so sad.
So with my minimal troubleshooting tools and experience… my theory is 1. The loose valves knocked carbon off and/or set a ‘new’ seat for the valves. Or 2. Playing with the IACV had it working for a little while, but then it has failed again. So I went with #1 and took the head off, now it’s in the shop being pressure tested and valves and seats cleaned up. With the head off I do see quite a bit of carbon on piston 1 and less carbon on the other pistons. I scraped most of the carbon off and inspected for cracks, etc. I’m still a little lost with this problem so every part on this Honda is suspect right now! However after the 275 miles of success I think it could be valve or carbon related, I can only hope. I should have the head back soon and I’ll post if it was worth the trouble of taking it off... or if I have luck with the CEL staying off now.

sick civics
 

sorry for delayed responce yes rotor was changed both times it come with dist from our parts suppliers , sounds like your compression in bang one and you have a strong honda il ask my tuner friends about you problems they always know thier x#$@

Make sure the back up circuit is working, if not the ECU will lose memory and reset every time the key is turned off. This causes unsteady idling on every start, since it needs to recalibrate every time. Also it will show the "not ready" code every time you try to smog test because the ECU resets when the key is turned off no matter how many miles were driven.

1999 Honda Civic HX P1399 code
 

OK, so I am also getting this code and I am a maintenence freak with this car. It is all stock and only had 119,000 miles when I had the muffler replaced. Then the hesitation started. I looked under the back and they put a HUGE muffler on this thing. Can back pressure be causing this (and possibly clogging the CATS?).

I don't know, but I have all the same symptoms as the other folks (missing, and now a blinking check engine light). my only code is the P1399, and all I can attribute it to is either the muffler replacement with one that has more back-pressure, or they didn't ground the car properly and I am chasing a ghost for what may have been damaged by a lack of proper grounding...

Thoughts?