MS3 Random misfire

[Kennyx]

Blue smoke = oil consumption
Black smoke = excessive fuel
White smoke = coolant go into combustion chamber due to bad head gasket

I cant judge your current issue base on the observation on exhaust gas alone ... any backfire after 3k rpm ?
0.8L / 1000km oil consumption is really no good , i have some naive idea ..lol .. ask someone follow your car and try maintain the rpm in range which backfire often take place ... see if any strong smoke coming out from your exhaust or not ..


KennyX

[kizzoalfa]

Blue smoke = oil consumption
Black smoke = excessive fuel
White smoke = coolant go into combustion chamber due to bad head gasket

I cant judge your current issue base on the observation on exhaust gas alone ... any backfire after 3k rpm ?
0.8L / 1000km oil consumption is really no good , i have some naive idea ..lol .. ask someone follow your car and try maintain the rpm in range which backfire often take place ... see if any strong smoke coming out from your exhaust or not ..


KennyX

Hi, I can try the smoke test but My coolant system is good, so white smoke is not an issue. I doubt it is blue but only at heavy load and only if I use too much in city without loading the engine. Question is that could the oilconsumption cause misfire?

[Kennyx]

Yes ... definitely ... i once having crazy backfire in my old ga16 nissan engine at high rpm .. but the smoke is super heavy when backfire happens ...im not sure yours..


KennyX

[kizzoalfa]

Hi,

I just checked again: (just came back from my garage)

End pressure is 5.2 Bars in all of the cylinders.

Spark plugs are as they should be. (Light brown.)

Measured compression ratio and it is 7.8 : 1 (I used oil to fill one of my cylinders, so it is valid.)

As I looked into the cylinders the piston tops are shining a bit so there must be some oil. Also I have some oil on the spark plug threads.

I attached pictures about my spark plugs. You can see the oil around but the ignition must be Ok since the center electrodes are burnt well (also checked megasquirt dwell time again today and changed back to 5ms from 5.5ms, no change in misfire).

One more thing I think we need to clarify, and it is the meaning of misfire. What I have is a small drop in engine pull, it is looks like one burn is not complete (AFR goes from 13 to 13.5 so unburnt fuel probably present or ignition not complete) but it is not a big boom, it is how I can say similar like you cruising and set AFR to 16:1 and over that you feel somebody is pushing back the car you have some not complete ignition randomly. (I do not know what is the right english word for this.)

Thanks,

Zoltan

[Kennyx]

that consider horrible man ...my old ga16 which drink oil like no tomorrow have cleaner spark tip than yours ....



KennyX

[kizzoalfa]

that consider horrible man ...my old ga16 which drink oil like no tomorrow have cleaner spark tip than yours ....



KennyX

Do you think the "misfire " could be caused by oil consumption? I think oil consumption should not effect this way.

I will rebuild my engine soon, but would be great to close out the msifire issue before new engine arrival.

Thanks.

[Kennyx]

Just from my own experience, will wish to listen from other forumer as well ..


KennyX

[kizzoalfa]

Just from my own experience, will wish to listen from other forumer as well ..


KennyX

We were listening for long time Anybody?

[jsmcortina]

Excess oil consumption is certainly not good and may effect your issue.

James