Slight engine 'bobble' and consistent misfires (P0300 / 302/303) - Mercedes-Benz Forum
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post #1 of 2 (permalink) Old 06-12-2019, 06:02 PM Thread Starter
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Date registered: May 2006
Vehicle: 2002 C32 AMG Black and 2003 ML55 AMG Black
Location: LA
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Slight engine 'bobble' and consistent misfires (P0300 / 302/303)

So my 2002 C32 - 138K miles - jet is having some issues.

Couple issues - it idles oddly at stop lights and has for some time. Its just an annoying 'bobble' that should not be there. Have yet to put my finger in exactly what is causing it.

Recently changed the fuel filter. Changed the plugs. Tested the plug wires - all seem good.

I have used seafoam several times and never had any issues. I have used it to clean the engine internally prior to oil change and also probably 5 times or so in the gas tank. I also recently used the 'spray in the throttle body' method a full can of the stuff. Thinking if the injectors were jacked, this might help. Sprayed, let it sit 30 min - then hard run - some white smoke as expected but not tons. Quick burst and then done. Probably went half mile and turned around and completely gone by time back at my garage.

Thinking it could be a couple issues.

1 . Plugs - doubt it - changed them.

2 . Plug Wires - doubt it - tested all of them. Got new ones.

3 . Cats - ?? - not sure. Some say seafoam or other 'additive' cleaners will mess them up. How to test which one?

4 . Vacuum leak - need to research more on DIY method to do this and where to input the smoke....could be this and just not sure where to look. Have tried spraying starting fluid around the engine several times and locations... nothing really stood out.

5 . Injectors - not tested - suspicious this could be the issue - hence the bottles of seafoam... after many foams... still bobbles. Still not sure on if I should pull them. Also not sure how a shop would test them. I called and got an estimate for like 150 bucks. They say they do it on the car. Not sure how that works but must be super easy for that little of money.

6 . Coil packs - not tested. Tested, swapped side to side... P0300/302/303 issue did not move with them.

Video of bobble at idle.

A bit hard to see the bobble. Sounds like a rickety mess in this video, does not usually sound that shaggy today (more on that below). I have commented over the years how clickety the engine has always sounded. The engine bobble at a stop light is enough to bug me, so much so that I put it in neutral on occasion to make it go away. Thinking is a easy fix and research will will the day.

Ticking 1 - 100K Miles..
Ticking 2 - standing beside car
Ticking 3 - relatively cold start
Ticking 4 - I thought part of the oil filter broke off... have now accepted that this is how it sounds... after much research here on the forum(s)
Ticking 5 - oh man... the clicking is brutal in this vid... haven't watched in a long time... 5 years ago.

Fast forward 5 years..

I did pull a bunch of gunk from my plenums. Not sure this is/was the bobble issue. Cleaned them out nicely and still have the bobble.
Still need to check my intercooler. Never wanted to get so far into a project where I could not drive the call for longer than a weekend. I still think the inter cooler has leaked over the years as I have had coolant loss when driving it hard and in hot temperatures. Have not had to add coolant in a long time, probably as I don't drive it as much and in my mind the leak may have sealed itself somehow given all the gunk in the plenums.

Video - Plenum Gunk

Now that you've seen that video, please comment and let me know if this is completely normal - it had 130K miles on it at the time that video was taken. Does all that crap 'confirm' that my super charger is leaking / has leaked... or just that this is what an engine looks like when you pull the plenums after 130K miles having never cleaned them before.

Blinking Check Engine Light - Oct 2017
I get blinking check engine light now at WOT on freeway and have to pull over to reset the car. The engine stutters badly after I kick it and pop the check engine light. I have intentionally done this twice to replicate the problem consistently. Something bad is up. I know this because I researched 'blinking check engine light'. Bad bad, stop, serious engine issue.

So I checked EGR valve

Not sure if this is the issue. After inspection and hitting it with some brake clean, I do not believe this is the issue. I am curious if this is how they should look or if additional testing can be done on this one.

Here are the current codes - P0300 / P0301 / P0302 / P0303 - and some I do not know what to do with... what they are... lately a P0420.

For the "8 Ready" - I have no idea what those are. Not sure how to use the reader thing fully...

Also saw a video of changing the super charger oil. Should I do that? Did not know that you could / should. How many have done that? Stumbled on video on youtube - never seen it brought up here in the forum. Update... I changed the super charger oil.. mine was a bit smelly but nothing terrible. Was an easy thing to do.

I assume the engine is supposed to sound like that. What I would call clickety / shaggy... not super smooth. Most videos I see on the web of AMG super charger engines of 2002 - 2007 sound similar (32s' and 55s really)
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post #2 of 2 (permalink) Old 06-22-2019, 11:05 AM Thread Starter
BenzWorld Member
Date registered: May 2006
Vehicle: 2002 C32 AMG Black and 2003 ML55 AMG Black
Location: LA
Posts: 53
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(Thread Starter)
Trying again... any ideas on what would consistently cause a P0300 / P0301 / P0302 / P0303. I can pop the CEL at will now with some strong acceleration. I am on the right track thinking its likely a clogged catalytic converter?
Could it be any of the following:
Purge Control Valve?
Crankshaft Position Sensor?
Camlobe Separation? What is this exactly? I found a thread where it has happened on the 2002's.
Oxygen Sensor?
Fuel pump?
Rings / Valves?

I feel good that I have ruled out - Plugs / Wires / Air Filter / Coil Packs / Fuel Filter

2002 C32 - 147K miles.

Thanks for your thoughts...
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