[Svilen Di]

Hello team,

Hope you're all doing good. As I'm not quite sure if this is the right place where I can ask you guys something, let me first apologize if I'm not doing it the correct way. Sorry for the weird English as well, not my mother language.

I'm a fresh owner of a 8th gen Honda Civic 1.8 S, 2006, hatchback (140k km) and I'm having the so-famous "random misfire detected" codes thrown constantly. Codes are P0300, P0301, P0302, P0303, P0304.
Here's what have been done so far:

1. Spark plugs - changed. Coils are okay.
2. EGR valve cleaned.
3. Flowmeter - cleaned with air sensor cleaner.
4. Fuel injector added - STP.
5. Valve ajustement has been made.
6. Replaced the whole chain with the tensioner.
7. ECU switched and tested from another car - issue persists.


The strange thing is that the "check-engine" led starts to flash only between 3000-3500 rpm and if I go quickly beyond this rev, all works just fine and the car is running smoothly. If for some reason I stay between 3000-3500 rpm for around half a min, the led pops-up and the cars loses power, then respectively - needs to be turned off/on - then all fine.

Changed the gasoline with high octane (100), same thing. All filters have been changed recently, battery is fine.

I looked up the forum here, but I wasn't able to find a resolution or anything close to my issue. Do you have any ideas what may be the reason for this?

Thank you in advance and have a good one!

 

[Grayfox]

Since you have a scan tool

What are the lambada readings whilst driving?
What are the fuel flow readings like?
When was the last time the air filter was changed?
When was the last time the fuel filter was changed?
Have you inspected the vacuum lines?
Have you done a balance test?
Have you done a compression test?
Have you inspected the coils with water in the dark?
Dont use 100 octane fuel with the FK2/FN1 as it is not needed, use 95.

Are the spark plugs the correct type?
Incorrect plugs can cause misfires.

Honda should only use NGKs.

 

[lightningslow]

Since you have a scan tool
Honda should only use NGKs.

Yeah i found this out but it still doesnt explain why dealers are still selling Denso's! Absolute load of rubbish spark plugs they are

 

[deni.babe]

wiring loom maybe...

 

[Grayfox]

Yeah i found this out but it still doesnt explain why dealers are still selling Denso's! Absolute load of rubbish spark plugs they are

Because in the service manual it will list the NGK plugs and the denso plugs.

If they cant get NGK they will use densos for what ever reason(price or contracts or even part availability)

 

[Svilen Di]

Thanks for answering, Grayfox.

All tests have been made by my mechanic:
- Balance test
- Vacuum lines
- Compression test
- Plugs are NGK iridium, as recommended by the books.
- Air and fuel filter changed 3 months ago (the car already was running with the "Check-engine" while it was changed).

We're thinking the whole problem comes from the RPM, not the engine load as everything works fine. For some reason it seems there's a fuel lean between 3000-3500 RPM which causes the engine to misfire. We noticed the arm-shaft (or rocker arm, hard to find the translation) not going into position correctly around 3000-3500 RPM and loading a bizarre noise. Now we'll se what will happen if we switch from another car for testing.

Except this, the car is running smoothly once above the 3500 RPM - enough acceleration, torque and power. Only if I stay between these RPMs for around even half a min - the led pops-up.

Will keep you posted, thanks for your help!

 

[lightningslow]

Tried the crank sensor?

 

[Svilen Di]

Yes, crankshaft sensor tested together with the camshaft's one - all working fine.

 

[dohowells28]

I have exact same problem on my 1.8 VTEC engine management light comes on if I stay at 3000rpm and the eventually VSA as well (this is due to misfire, VSA is fooled into action according to another forum) did you fix yours? I am 4 weeks trying to sort!!!?

 

[Svilen Di]

Nope, 4 months now and we're still struggling with this problem. We can't find a car to try switching the arm-shaft/rocker arm so we can be completely sure this is the issue. Let me know if you managed to find something else, would be great.

 

[dohowells28]

Trying the following this week:

1) Change crank sensor
2) Connector to the crank sensor - check for corrosion on contacts
3) VTEC solenoid and gasket at the rear of the head furthest away from battery, has a rusty looking cap and an electrical connector going into top

Will let you know how I go.

 

[DkHonda]

We have same problem with a Civic 2006 1.8 the problem is between 2500 - 3000 rpm.

Change:
Chain & tension.
Spark plugs
Crankshaft sensor
Fuel filter

Switch from anoter civic:
MAP Sensor
MAF Sensor
EGR Valve
Fuel Injector All 4
Ignition coils All 4
Lampda

Control:
Fuel presure
Valve adjustment.
V-tech valve cleaned
Valves control for sooting (look from outside
intake manifolds)
Engin Temp. sensor

 

[dohowells28]

Plugged OBDII into it last night and was getting crank sensor data so the problem doesn't lie there. Have not changed VTEC Solenoid yet but don't think it's that.

I am losing my battle.

DkHonda - are you saying you have tried all those things and it still doesn't work?

Did yours just start happening or was it after maintenance - mine was after changing coolant and auxiliary drive belt.

 

[lightningslow]

what about the tensioner for the aux belt? have you tested the alternator?

 

[dohowells28]

The alternator is giving a reading on OBD but not really sure what I am looking for or at really. What values should it show? Would a tensioner/alternator cause misfire 1-4 and random? It only happens when you rev between 2500-3000rpm and hold the revs there. Otherwise it revs through the range well.

 

[DkHonda]

dohowells28 on mine it misfired before all this things change and switched from another civic the chain was to longer than the min. data so we change the chain..
yeah have tried everything i wrote above..

 

[dohowells28]

And still doesn't work?

Sent from my HUAWEI VNS-L31 using Tapatalk

 

[DkHonda]

Nope unfortanlly not

 

[dohowells28]

Time to get rid. Gutted.

 

[lightningslow]

The alternator is giving a reading on OBD but not really sure what I am looking for or at really. What values should it show? Would a tensioner/alternator cause misfire 1-4 and random? It only happens when you rev between 2500-3000rpm and hold the revs there. Otherwise it revs through the range well.

Take it to a car electrician specialist. That could be an electrical fault which is load based