Cyclinder 3 Misfire
Thread Starter
Newbie
Joined: Aug 2010
Posts: 8
Likes: 0
From: D.C.
2004 C230K 1.8L
Cyclinder 3 Misfire
Hello all - I have a peculiar misfire I hope I can resolve with the help of your expertise. My bluedrive indicates code P0303 Cylinder 3 Misfire. Some things to note..I can floor it from park, without a misfire. However, say I'm going 50+ in 5th gear....and put even a little extra load on accelerating (I discovered the issue driving on a freeway when I was cut off and had to accelerate quickly), the misfire occurs and I have to pull over and shut the car off. If I drive it smooth on the pedal without major load it's ok...slightest bit of extra load and its misfiring hard.
Thank you in advance,
AC
Thank you in advance,
AC
MBWorld Fanatic!
Joined: Jun 2002
Posts: 7,263
Likes: 169
From: So. Oregon Coast
C230 Sport Coup + 2006 W164 ML350 + 99 Ford Escort RIP
Plugs and or coil.
I was going through coils like mad at one point, till
a mechanic told me, more likely the plugs.
Old plugs stress the coils.
Don't figure on more than 50K miles on stock plugs (the GOOD iridium plugs sold by MB and made by NGK and you can buy from NGK much cheaper),
15K for copper or 30K for iridium IX (cheap version NGK iridium).
So, now, I have no problems.
Move the coil to another cylinder and see if the problem moves with it.
I was going through coils like mad at one point, till
a mechanic told me, more likely the plugs.
Old plugs stress the coils.
Don't figure on more than 50K miles on stock plugs (the GOOD iridium plugs sold by MB and made by NGK and you can buy from NGK much cheaper),
15K for copper or 30K for iridium IX (cheap version NGK iridium).
So, now, I have no problems.
Move the coil to another cylinder and see if the problem moves with it.
Thread Starter
Newbie
Joined: Aug 2010
Posts: 8
Likes: 0
From: D.C.
2004 C230K 1.8L
Please see the coil picture
Bottom of Coil
Plugs and or coil.
I was going through coils like mad at one point, till
a mechanic told me, more likely the plugs.
Old plugs stress the coils.
Don't figure on more than 50K miles on stock plugs (the GOOD iridium plugs sold by MB and made by NGK and you can buy from NGK much cheaper),
15K for copper or 30K for iridium IX (cheap version NGK iridium).
So, now, I have no problems.
Move the coil to another cylinder and see if the problem moves with it.
I was going through coils like mad at one point, till
a mechanic told me, more likely the plugs.
Old plugs stress the coils.
Don't figure on more than 50K miles on stock plugs (the GOOD iridium plugs sold by MB and made by NGK and you can buy from NGK much cheaper),
15K for copper or 30K for iridium IX (cheap version NGK iridium).
So, now, I have no problems.
Move the coil to another cylinder and see if the problem moves with it.
Thread Starter
Newbie
Joined: Aug 2010
Posts: 8
Likes: 0
From: D.C.
2004 C230K 1.8L
@slammer111 , if possible, a second opinion of how to move forward would be much appreciated.
Thanks!
AC
Thanks!
AC
Last edited by Acortazzo; Mar 29, 2019 at 01:47 PM.
MBWorld Fanatic!
Joined: Dec 2003
Posts: 3,275
Likes: 236
From: BC, Canada
2003 C230K Coupe Orion Blue
No reason why that stuff is in there. Maybe some mechanic got that stuff in there by accident? It's an electrical contact. The spring should be bare.
Remove all that guacamole and also clean the metal terminal of the spark plug. Add some dielectric grease to the ceramic spark plug base (watch a video online to make sure you're doing it properly), and reinstall ignition coil.
Remove all that guacamole and also clean the metal terminal of the spark plug. Add some dielectric grease to the ceramic spark plug base (watch a video online to make sure you're doing it properly), and reinstall ignition coil.
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Thread Starter
Newbie
Joined: Aug 2010
Posts: 8
Likes: 0
From: D.C.
2004 C230K 1.8L
Certainly didn’t seem like it belonged. I removed that residue and swapped the coil. Misfire in 3 continues. I then pulled the plug out of 3, which had some white on the spark indicating it possibly was running lead in that cyclinder. I swapped the plugs of 2 and 3 and boom, misfire moved to the other cylinder.
No reason why that stuff is in there. Maybe some mechanic got that stuff in there by accident? It's an electrical contact. The spring should be bare.
Remove all that guacamole and also clean the metal terminal of the spark plug. Add some dielectric grease to the ceramic spark plug base (watch a video online to make sure you're doing it properly), and reinstall ignition coil.
Remove all that guacamole and also clean the metal terminal of the spark plug. Add some dielectric grease to the ceramic spark plug base (watch a video online to make sure you're doing it properly), and reinstall ignition coil.
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