Mercedes-Benz Forum banner

1 - 15 of 15 Posts

·
Registered
SLK in brilli silver
Joined
·
854 Posts
Discussion Starter #1
Here is the situation with the car (99 230) The car had been running very well lately feeling more powerful than usual, running pretty smooth, little hesitation etc. It has been pretty sunny and warm, downright hot for the bay in the last week. It rained yesterday prety heavily and today it was hesitating, and felt like it back to less than full power. As I tried to accelerate it felt clear to me it was misfiring AGAIN and the check engine light came on. I have not pulled the codes but I am 99.99% sure it will be the usual ones it has thrown previously, multiple misfires on cylnders.

So far what has been replaced:
coils
MAF

Im at a loss, and while it is possible its chance that the weather was crappy and the car was having issues again it seem highly unlikely since everytime come to think of it has thrown codes that the car was in the weather and it was raining.

Any ideas??? [V]
 

·
Registered
SLK in brilli silver
Joined
·
854 Posts
Discussion Starter #2
not sure if this will help or not but the car as 56k on it and I also had a 'tune up' aka the plugs changed last visit
 

·
Registered
SLK in brilli silver
Joined
·
854 Posts
Discussion Starter #3
I will pull the codes tomorrow. Stupid question but where is teh o2 sensor located?
 

·
Registered
'01 SLK230,'93 190E 2.3, 1971 LS5 Corvette Convertible
Joined
·
2,185 Posts
linh - 5/5/2005 11:27 PM


Lol...ok, now i see the second pictures also that showed the 02 sensor #1.
Hey Linh, I went back and snuck it in while you were taking a leak. By the way....WELCOME BACK!!!
It's not the same here without you.

Dave
 

·
Registered
SLK in brilli silver
Joined
·
854 Posts
Discussion Starter #6
Great info guys have no idea how much I really appreciate it! Now the other question how do i know which o2 sensor to replace? will the codes give me a clue? I have a real funny filleing its gonna be multiple misfires on multiple cylinders.

Also even though the car is out of warranty wouldnt this be an emmissions warranty which is 7 years right?
 

·
Registered
SLK 230
Joined
·
1,007 Posts
You say you had the coils and plugs changed, but what about the leads ? maybe they are past thier best, and the damp weather won't help them ??
 

·
Registered
SLK in brilli silver
Joined
·
854 Posts
Discussion Starter #8
by leads do u mean spark plug wires and those funny looking rubber extender parts. I will list the codes later today after I get a chance to pull em.
 

·
Registered
SLK 230
Joined
·
1,007 Posts
plug wire leads

by leads do u mean spark plug wires and those funny looking rubber extender parts. I will list the codes later today after I get a chance to pull em.
yeap, thats the parts i was talking about.
 

·
Registered
SLK in brilli silver
Joined
·
854 Posts
Discussion Starter #10
Okay the only code I could pull was P0303, which is misfire (again) on cyn 3.... any ideas guys, could it be the 02 sensor still causing this. A mechanic @ autozone (there getting parts) also thought it could be injectors. BTW this is the first time only one cyl was coded, previously it was multiple cyl misfires or 3,4,2 w/codes.

Strangely enough it stopped raining for about 36 hours and the car has stopped its hesitating....

I think this problem could be over my head but would like some ideas when I bring it into the shop, or would love to save a buck and do it myself....
 

·
Registered
SLK32, ML430
Joined
·
6,349 Posts
I am sure you have done this but I will through it out there anyway. Have you checked the battery? I had a previous car that had issues starting and/or running rough in rainy/very humid weather. It did not happen all the time (in fact there appeared to be no rhyme or reason) after going through this for an number of months I finally battery and it took care of all the problems. Funny thing was when the battery was tested it showed it had plenty of juice.
 

·
Registered
2000 Designo SLK-05 C230WK-05 E320CDi-2010 GLK 350
Joined
·
714 Posts
The big clue here is the humidity and how your problem gets worse in humid conditions. Wet weather and old plug wires do not get along. This is made worse by worn spark plugs with larger than normal or misadjusted plug electrode gaps. When the voltage to jump the worn gap gets too high the current will find another path. Next time it is misfiring which should be today since its raining now, park the ride in a really dark place and let it run with the hood open so you can visually examine the path between the coils and the plugs. You are probably getting arcing between the plug boot and the cyl head but check the entire path. Arcing will appear to be a faint blue color flashing, but you may also be able to hear it snapping as well.
 

·
Registered
SLK in brilli silver
Joined
·
854 Posts
Discussion Starter #14
Will give that a try today. I doubt the coil is bad, its barely 2 months old and yes they are exactly the same im quite sure of that but I will move the two around just to check it out and see if it does it again.

Thanks guys so far, I will look for the archin.
 

·
Registered
SLK in brilli silver
Joined
·
854 Posts
Discussion Starter #15
Quick update. It has been raining pretty much the whole day I go out fire it up and no problmes at all, running smooth and quiet. Thanks for all your guy's help suggestions when it happens again I will do as suggested.
 
1 - 15 of 15 Posts
Top