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Discussion Starter #1
Hello all,

I recently got a check engine light, loss of acceleration and slight shake. So, I pulled to the side and restarted the car and everything was working normally again.
Upon reviewing the code, it showed P0300, P0302, P0303. So, I suspect cylinder 2 and cylinder 3 misfired and since it was two cylinders, it threw P0300 which indicates multiple cylinder misfiring.

So, I parked it in my garage and today the CEL is gone and the car is driving normally.

So, can you please tell?

1) If I should be worried and have a mechanic immediately look at my 2 and 3 cylinders or all of them??
2) Once the cylinder misfire occurred, does it disable cylinder 2 and 3 to avoid further damage and leaving the regular power delivery from rest of the four cylinders?
3) Once the cylinder misfire occurred, does it keep misfiring all the time or will it misfire in certain circumstances like high rpm, high speed, fast acceleration or something?

Any estimate on what would it take to fix it and any estimate on reasonable cost to have it fixed?

Thank you
 

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Welcome to the forum! There are many causes for misfires, but a misfire on one cylinder won't shut down another. If it happens again, I'd check the plugs, wires and coils for any obvious problems. Also, you can try swapping plugs, coils and wires but ONE AT A TIME with a misfiring cylinder to a properly operating one to eliminate those parts.
 

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Discussion Starter #3
@rudeney

Thank you. I had the flashing CEL and it stayed on. The next day, the light was gone and its' been a couple of weeks that the light hasn't come back and it's driving normally with slight rough idle.
Could it be temporary or is it waiting for something big to happen?
I went to the mechanic but he said, I should wait until I get a CEL again and come back to them so that they can diagnose and fix the issue.
I am not sure if I should go to some other mechanic or do as the mechanic told me since the CEL went away and now its been 2 weeks without any issue except slight rough idle.
 

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A flashing MIl means that is is currently misfiring. An illuminated MIL means there is an active stored code. If the condition stops occurring, the MIL will extinguish after 5-1 start/run/stop cycles. However, the code will still be stored, so it's still worth getting it scanned.
 

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Hello all,

I recently got a check engine light, loss of acceleration and slight shake. So, I pulled to the side and restarted the car and everything was working normally again.
Upon reviewing the code, it showed P0300, P0302, P0303. So, I suspect cylinder 2 and cylinder 3 misfired and since it was two cylinders, it threw P0300 which indicates multiple cylinder misfiring.

So, I parked it in my garage and today the CEL is gone and the car is driving normally.

So, can you please tell?

1) If I should be worried and have a mechanic immediately look at my 2 and 3 cylinders or all of them??
2) Once the cylinder misfire occurred, does it disable cylinder 2 and 3 to avoid further damage and leaving the regular power delivery from rest of the four cylinders?
3) Once the cylinder misfire occurred, does it keep misfiring all the time or will it misfire in certain circumstances like high rpm, high speed, fast acceleration or something?

Any estimate on what would it take to fix it and any estimate on reasonable cost to have it fixed?

Thank you
I'd try swapping the ignition coils and wires around.

The firing order is:
3 6
2 5
1 4
(front of car)
Perhaps 2 to 1, and 3 to 4. Then reset the CEL light. If the misfire becomes 1 and 4 afterwards, then its most likely bad ignition coils.

Also, If your car has never had the MAF sensor changed, I'd change that with a Bosch unit($110 on ebay). Cheap part, all things considered and a relatively easy install(see youtube).

I just had this issue on my car, and car is running great again with all new coils and a MAF change.

G'luck.
 

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Discussion Starter #7
Thank you for the tips. I have 160k Miles.
I also strongly feel it is MAF sensor.
Today, when I changed from Reverse to Drive, the car shutdown.
Then the car started normally and drove up to my home. When I changed from drive to park, the engine RPM rev'd itself and increase from 10 rpm to 40 rpm and I turned off my car as a precaution.
All these symptoms point to MAF sensor in my opinion. Do you guys concur?
Also is it hard to replace the MAF sensor myself? I could find a used but excellent conditon BOSCH MAF sensor for $35 from a junkyard. Thinking to DIY if its not hard or if something doesn't break too easy and I need a mechanic for that.

P.S. I didn't get any check engine light today which is odd.
 

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To answer your question in the original post, the computer will shut down any misfiring cylinders until the key is turned off. Restarting the engine is the only way to get them to fire again (at least until they misfire again).

What I didn't see in your posting is that you pulled all the spark plugs out and checked for proper gap and/or replaced them recently with new ones. Swapping the coils and wires around is another good way to determine if those parts are good or bad. Perform basic troubleshooting like this first before moving on to troubleshooting more complicated systems.

You have a lot of miles on the car, so beyond that I would start looking at things like cleaning the throttle body and perform the throttle body relearn procedure with the gas pedal. I have seen a couple of cases where this fixed the misfiring cylinder problem. Replacing the MAF without performing these other things is just guessing. Guessing can lead to a very expensive repair bill.

As a side note, your rough idle may be caused by a different issue. Your ME may be on software version 11/02 or before. You want to be on code update 12/03 for the ME that fixed the rough idle. I don't have access to the bulletin for this issue, but you can read about it in this post from 15 years ago. https://www.benzworld.org/threads/c240-rough-idle.1169085/ Maybe a member on this site can give us the bulletin number for it.
 
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