What does a misfire sound or feel like? - PeachParts Mercedes-Benz Forum

euronatura · #1 01-16-2004, 11:19 AM

This may be a stupid question but I have read alot about misfires and the damage it can cause. So my question is: How does a misfire sound or feel like? Or if one can not hear or feel it, is checking the spark plugs teh way to go to see if this occurs. I do not think that my car misfires since it purrs like a kitten and runs great but out of curiousity I post this question.

thanks, iggy

ejsharp · #2 01-16-2004, 03:42 PM

If there are interuptions in the purring then it is a misfire. The severity and nature of the misfire points toward the cause.

stevebfl · #3 01-16-2004, 09:58 PM

Go to one of your cars and pull a plug wire. Place an old plug into it and set it on the manifold or block. Start the car and you have a single cylinder misfire.

It will feel like a vibration at engine speed. It will change frequency as the engine speed increases. If driven it will be more pronouced and be accompanied by a reduction of power.

yhliem · #4 01-17-2004, 12:54 AM

Quote:

Originally posted by stevebfl
Go to one of your cars and pull a plug wire. Place an old plug into it and set it on the manifold or block. Start the car and you have a single cylinder misfire.

or you could do the above and skip the "Place an old plug into it and set it on the manifold or block. " part.

stevebfl · #5 01-17-2004, 08:09 AM

Yea thats the way I would do it, but when giving info publicly I try and do it by the book. Open ending secondary ignition always takes the risk of sparks going where they shouldn't. In the case of Honda many have the ignitor (ignition module) inside the distributer and the most common cause of burned ignitors is arcing due to poor plug maintenance.

In the case of MBs if you open circuit a plug you will probably arc across the top of the coil or distributer cap. Once that has happened, that track is there permanantly and will be offer an easier path next time secondary is taxed.

yhliem · #6 01-17-2004, 02:09 PM

Quote:

Originally posted by stevebfl
Yea thats the way I would do it, but when giving info publicly I try and do it by the book. Open ending secondary ignition always takes the risk of sparks going where they shouldn't. In the case of Honda many have the ignitor (ignition module) inside the distributer and the most common cause of burned ignitors is arcing due to poor plug maintenance.

In the case of MBs if you open circuit a plug you will probably arc across the top of the coil or distributer cap. Once that has happened, that track is there permanantly and will be offer an easier path next time secondary is taxed.

good point