2000 Civic Ex
Stock d16y8 manual
Previous Maintenance: plugs, wires, cap, rotor, fuel filter

Okay, so I've been having a misfire issue for a good bit, but it wasn't very consistent / bad until this week.

My misfire happens at idle causing it to idle low (low like almost 200-300?), it also happens under load while cruising, and it also happens sometimes while accelerating...

This morning, my car threw misfire codes P0300, P0301, P0302, P0303, P0304, and P1399.

My idle also got "stuck" at 3k rpm (today was first time it every did that). But now it is back to the low idle as before and has not repeated this behavior.

My chosen starting point was the 'Random Misfire' diagnostic in the FSM.

Given my misfire conditions, I chose "Not Specific" for my troubleshooting section. I checked the fuel pressure with a gauge and vacuum on / off pressures were right in the middle of their respective ranges.

Sorry for the pic, not sure how else to take a picture of a pdf...



Next check was the distributor / wires. I pulled the cap, rotor, and shield off the distributor.

The coil had burn through holes, cracks, and hot spots on it, so I replaced it with a new unit. The car does drive better, but still suffers from the random misfiring and rough idle.



Here is where I ran into some questions...testing the ICM wires.

I was testing the leads as the manual says to..


Blk/Yel = Bat. Voltage (check)
Wht/Blu = Bat. Voltage (check)
Have not done step 5 yet ( i know, i know)
Yel/Grn = No cont. to ground (check)

And step 7 is where I got stuck, (check cont. between blue wire at tach test connector and ICM)...I don't have a BLU wire at all. I see the 4th spade sticking out of the ICM but I do not have a wire connected to it, i can find no broken / disc wire inside the distributor harness either..

Do some of the civics not use the 4th blue wire, what is this wire for?? (**Edit: I did notice that my TEC distributor had a HITACHI ICM installed, should I be concerned with this?**)

I took the car to autozone and took my ICM out to be tested via their machine. I watched them hook it up correctly and the module tested all green lights :/.

I still need to test the map sensor and crank position sensor sometime this week, but thought I would start a thread here thinking maybe someone had some good insight for me.

 

How old are the spark plugs, wires, cap, and rotor? What brands of the latter ignition components are currently installed?

 

Plugs, wires, cap and rotor were replaced ~ 5k miles ago (Sept. '13).

Plugs and wires are NGK. I also verified the gap on the plugs prior to install.

The cap and rotor are YEC.

 

So I did the full FSM test on the crank angle / tdc / whatever sensor in the distributor.
The sensors tested good and the tests were consistant from the ecu harness as required.

I also tested the crank fluctuation sensor, though the connector has seen better days, it passed as well as the ecm harness check:




While I was on my way home today, the car randomly kept blinking the cel at me. I noticed that switching from 5th gear to 4th (bringing the rpm up past 3k) seemed to smooth out the misfiring/power delivery quite a bit. I repeated this test at least 3-4 times.

I'm thinking about changing from "not specific" to "low rpm and load". The does not misfire if I put the clutch in and rev the car freely.

**EDIT** I just went out and tested the IAV system per the FSM. The connector sees battery voltage, as does the wire at the ecm connector. I can also hear the IAV clicking when the circuit is shorted as directed.

RECAP:

CKP: Good
CKF: Good
IAV: Good
All three of these components list replacing the ECM if they are tested good (though I do not have DTCs for these items).

ICM: Good
Fuel Pressure: Good
Ignition Coil: Good (replaced due to wear)
Cap / Rotor: Good
Plugs / Wires (NGK): Good.

So what's left according to the manual:

Possible bad ECM: How do I check for this? Scan tool only? I don't have another to swap in..
MAP Sensor: Can check voltage at idle, ref. volts, and ground?
Valve Clearance: This will have to wait until the weekend where I have time to check.

 

Another update for those who will search in the future:

Tested the MAP sensor according to threads on here.

Tested the red/grn wire.
- Engine off (power on) = 2.83v
- Engine on (cold idle 1500rpm) = .750v

I have read that the map should read 3v at atmospheric, so should this be a concern or close enough?
I will check the wiring at the sensor plug and the ecm for proper voltage tomorrow when I get time.


Also went ahead and checked the TPS voltages for giggles and the closed / WOT voltages were pretty close to the .5/4.5 requirement (within .1-.2 volts as steady as I could hold my leads).

 

Bump.

The misfiring is bad enough that I'm worried for my cat / motor.
To have my ecm / o2 / map thoroughly tested / checked, I decided to call Honda .

However, they stated that they do loner cars :D So at least I can still get to my training without issue (Army stuff, yay).

Will update the thread when I get some answers (hopefully). Hopefully it's not something I checked and found 'good'.


BTW: referring to my op, can anyone answer why my TEC distributor does not have a (BLU) wire for the ICM 4th pin?

 

Why do you choose to leap to complicated possibilities before you have ruled out the most simple and common ones?

 

My plugs, wires, cap, rotor, iac, ckp, ckf, fuel pressure, icm, and ignition coil have all been checked and confirmed good.

No need for angry bold typing if you aren't going to elaborate, by all means I defer to your experience over mine if you have something to contribute.

 

How old are each of these components?

 

They were all replaced in September 2013, approximately ~5k miles ago with no misfire issues until last week.

 

Voltage and short test the Yel/Grn distributor wire.

If you unplug the primary O2 sensor, does the misfiring cease?

 

I get mere mV out of the yel/grn dist wire with key on/off.

No short to ground was found.

I can't get at the o2 sensor wire with the car on the ground in the street, I tried disconnecting it from above, but i can't with one hand.

More pissed now because there's oil on my oil pan....after I just replaced the oil pump o-ring and the front main (oil pan gasket was done back in sept), got an oil drip on the bottom of the timing cover forming....can't win with this freakin car

 

With the wire connected to the ICM and key in ON(II)?

 

i tested the yel/grn wire at the connector for the dist. it was disc. w/ key on, am i incorrect?

 

With key in ON(II), measure voltage to body ground at the Yel/Grn wire (connected to the ICM).

 

Do a leakdown and compression test.

 

I will pull compression this weekend.
I'm so busy with Army stuff this week, I did let Honda have a poke at it while I drive their loaner CRV (). Their master tech was stumped yesterday, lol.

 

Not sure if this is helpful but my Crv was having the same issue, same codes and all. After being stumped for about a week I noticed the exhaust cam was a tooth off. Come to find out the timing belt way overdue for a change (110k miles) and after replacing that and resetting the timing it runs like new again.

 

Well, after paying my pound of flesh to Honda, I got my car back.

My pride feels a little beat up, what's done is done, live and learn I suppose. I just wanted to make sure and update this thread for future searchers.



The tech claims that the codes I was getting were 'old' codes and that he only pulled cylinder 3 misfire...I cleared the codes according to the FSM multiple times to confirm the fault...meh

So he said that cylinder 3's plug had started backing out and the gap was way off...
I'm happy it's fixed, but stumped as I know I checked the plug and re-gapped them prior. I also don't know how I kept getting 300 ,301-304 when he got just the 1 code and 1399 (general misfire).

Since I got tagged for the diag. fee for a loose plug, he also did a leakdown check and compression check for me.

Compression:

170/176/175/175

Leakdown check also passed

Drove it back from the dealer and no misfires or CELs.

They were at least nice enough to give me a pre-sale inspection (cost like $75.00 and includes alignment check and ac system check etc) since the diag. fee was for something so stupid >.<

 

The reliable way to clear CEL codes from the ECU is to remove the 7.5A Back Up fuse for at last 3 minutes. What did you do?

 

I removed the backup fuse that the fsm references.
I also had the battery disconnected, but I do not know if that clears hard faults.

The misfire has come back with a furious vengeance on the way home >.>

Called Honda and the service manager says any more diag. time is on their dime since they told me the fault had been corrected. I'm gonna have them check the valve clearance while I'm at work as that IS one thing I have not gotten to check yet, and when I talked to the tech he did not bring up inspecting for improper clearance.

Ron, I'm gonna guess you updated my thread title? Thank you.

 

I don't care what anyone says, I give you mad props for EVEN pulling out the meter and trying. With that said, as of lately the only way a misfire can happen, as what I've seen regularly is spark plug and wires and icm. Now as Ron said, unplug the o2 sensor and see if its still backfiring and we'll go from there.

 

I have training all day again tomorrow (finance and veterans' benefits classes :p), but I will unplug the o2 sensor as soon as feasible and test drive and post updates.

Will also check valve clearances and post that too.

Besides damage to my cat, should I be worried about any kinda of catastrophic damage to my motor? I've never dealt with continuous misfire faults like this..

 

Valve clearances adjusted: specs for cylinder 1 and 3 were out. Adjusted everything to spec and was still misfiring.

Decided to pull the fuel rail and the injectors were all gunked up.

Cleaned the fuel injectors and then ran some fuel cleaner and cleared the misfire codes.

The car is running much much better and no longer misfires. I have only driven the car an hour or so today, so will report back if anything changes.

No hesitations, the idle is cleared up, and it accelerates smoothly. Plan to run some seafoam or something through the car at next fill up.

All in all, the only parts I actually ended up buying was a fuel pressure gauge and an ignition coil (that needed replacement anyways).

Nice to have no yellow light again, but honestly the most frustrating part about this whole ordeal was that I pulled the random misfire code + cylinder 1-4 misfire multiple times, only to have the dealer magically pull codes for only cylinder 3