d1no

Damn I hate it when that check engine light goes on :/.. It happend after a 15 minute highway drive.. I pulled the codes and i got P0302, P0304, P0313, and P0313 Pd.. They seem to be like misfire codes or somethin.. The guy at the shop said i needed a tune up and new spark plugs should take care of it.. I cleared the codes.

The car is an 05 m271 with 66k on it and im sure no one has ever changed the stock plugs.. I think all recalls are done on it.. The car idles kind of rough right now and the idles keeps fluctuating around 1000 rpm and below like im revving the engine a bit while im not..

so what do you guys think should the spark plugs take care of this? thx

LILBENZ230

Are you sure the $12 hose recall has been done? You don't have any bad gas in it? My 05 has 86600 miles and runs great on stock plugs.

d1no

Well a carfax showed the car has no open recalls and it has been running great for 10k I bought it with 55k.. should I just try new plugs

Glyn M Ruck

P0313 = Misfire Detected with Low Fuel.

P0302 & P0304 = misfires on cylinders 2 & 4

Check - Plugs, wires & coilpacks. When last did this car have a new fuel filter?

laneshift

lol, everyone seems to overlook the fuel filter, and it makes such a big difference!

LILBENZ230

My fuel filter hasn't been changed, either. I was going to wait until it showed some sort of symptom...?

laneshift

IMO, when it starts showing symptoms, it's probably a little late for comfort. I'd change it, because with the correct jacks, it's pretty hassle-free. MB suggests it be done at 65k.. can't go wrong with replacing it if you're due is my $0.02.

d1no

Thx.. well I have never replaced the fuel filter and will assume it never has been replaced.. how would I go about checking the spark plugs and coils? Also where is the fuel filter located? Does the rear seat have to be removed? Is it ok if drive the car to work its only a short distance not even 10 miles?

Glyn M Ruck

See laneshift's thread. I posted diagrams there. You check coilpacks & wires by swapping around with another cylinder & seeing if the misfires change cylinder - plugs you just replace.

https://mbworld.org/forums/c-class-w...ll-20-sec.html

samaritrey

Search on here for the fuel filter diy not that hard you do it from under the car.

d1no

^ ok will do but in the meantime is it ok for me to drive my car for short trips without doing any of this (no time) or should i leave the car alone?

laneshift

If the car is running okay, no shaking, etc, and it's just the light, I'd say short distances are fine. If your car happens to misfire, you'll lose power and hit limp mode. Just pull over, restart the car, and it'll reset.

Don't lag on fixing it, though! Good luck!

Glyn M Ruck

Clogged fuel filters do not do the injection system any good at all. The pressure regulator is in the filter as well & can mess around. The fuel pump has a hard time & cavitates. Injectors are cooled & lubricated by the fuel. You don't want any aeration in the fuel rail due to cavitation. Don't wait for driveability problems.

d1no

car runs fine.. but when i let it idle it goes up and down a tiny bit which makes it shake slightly.. i erased the code but it cam back upon restart.. should i do fuel filter first or plugs? or just do both?

Javvy

forget the plugs do the fuel filter, listen to the gurus man.......all of them are sayng fuel filter and you are still harping on the plugs.......chage one thing at a time and save $$$$$, fuel filter will do the trick and for the 2% chance it does not then hit the plugs....jeeeeeeezzzzzz

Glyn M Ruck

I must admit I would do both!

d1no

i bought the fuel filter.. advanceautoparts had some 20 dollar off coupon.. total came out to be like 35bucks which is the cheapest i found anywhere.. i think the purolator is a rebranded bosch filter? im gonna try to change the filter and see how the car reacts if it doesnt fixes it ill be doing the spark plugs too

LILBENZ230

The oil filer they sell as Purolator is a rebranded MANN filter. So I'd suspect that to be a rebrand too.

d1no

^^ Yeah most likely, it says its made in Israel which I beleive the other one is too.. Do I have to use oem brand spark plugs or are other ones fine because my auto parts store doesnt have em in stock..

d1no

are these spark plugs fine Autolite Xtreme Performance Spark Plug? its all they have in stock for the car and i dont want to wait to order.

here are the specs..
Center Electrode Material: Iridium Alloy
Thread Reach (in.): 1.000
Gasket or Seal Included: Yes
Length (in.): 3.306
Seat Style: Gasket
Center Electrode Core Type: Copper Core
Rib Configuration: Standard
Terminal Top Type: Fixed
Hex Size (in.): 0.625
Number of Electrodes: 1
Insulator Type: Standard
Ground Electrode: Nickel Alloy
Heat Range: 5
Style: Finewire Iridium Enhanced
Tip Configuration: Ir Finewire Double Platinum
Center Electrode Firing Tip: Finewire
Gasket Installed or Loose: Installed
Thread Size/Diameter (mm): 14
Sealing Type: Copper-Glass Seal
Side Electrode: Yes
Resistor: Yes
Resistor Type: 2,000 - 20,000 ohms

it says it will fit my car

samaritrey

I would honestly only buy oem plugs order them online and you can have then for next weekend.

Glyn M Ruck

Fit original OEM Bosch!

91RS

Only use factory parts, I've never seen any vehicle that ran right for a long period of time on non-OEM plugs/wires/etc. Definately don't waste too much time getting this repaired, when the engine is misfiring it is sending raw fuel down the exhaust which is no good for the cats (which are quite a bit more costly than fixing a misfire).

d1no

thank you guys.. im going to order Bosch FR6MPP332 Platinum Spark Plugs which i beleive is the oem plug for my m271

LILBENZ230

I thought Glyn said in Lane's thread that when the engine detects a misfire on a cylinder, it shuts down the injector - thus not sending raw fuel through the exhaust.