I have a misfire in cylinder 1 and the scanner gave a p0301 code, what is my problem? I have a 2002 E320(w210).Ive recently replaced my spark plugs, all ignition coils(6), and fuel filter in the past month and still there is a lil bad ideling,shaking in my steering wheel, and loss of acceleration. It has gotten better since replacing parts but it is still not running like a benz is supposed to and how I would like it to.Any info will be greatly appreciated.Thanx.

 

What is it with you guys replacing coils?p0301 is the code for a misfire on cyl 1.
Who did the plugs,how many miles on the car?why new coils?have you checked the motor mounts?Have you checked the plug wires are pushed onto both plugs on cylinder 1?Do you know where cylinder 1 is?
Post the anwsers to the above and then we can start on the solution.
ohlord
"GOT CODES?"
I think you posted this on another thread ,correct?the wet plug guy?go to a different trusted mechanic this guy is ripping you off.Coils, plugs,wires at how many miles?He is just tossing in parts in the hopes of finding a solution... He does not know what the hell he is doing.You either have no spark to cyl 1-wet plug- or a faulty injector leaking down or clogged and just dribbling fuel instead of spraving-wet plug- or a blown head gasket leaking coolant into cyl 1-wet plug-.
find a qualified mechanic or learn to test these items and you will find the solution.

 

Hi,

I understand why you are at a loss!

So lets start again.

Was the OBD memory reset after you read the P0301 code?
If so has a P0301 code returned? If not start with this step.

If a P0301 remains you continue to have a Misfire on No1 (as detected by OBD) which fits with your personal observation.
So the question is why do you have a misfire on No.1?

Could be Ignition / Fuelling / Mechanical/Other problem!

Lets start with observe Plug colour vs others. Is it the same or different?

I will assume different. So No1 isn't firing correctly. Usual "low cost" solution is to swap plug, leads and then coil pack with parts from another cylinder. Does the problem stay put or move to the other cylinder. If it moves the code will become P030X where X is the cylinder misfiring. If it moves either the plug, lead or coil is faulty. If it doesn't move then you are down to Fuel or Mechanical. Best to put parts back in original locations and confirm problem persists.

Next "low cost" step is to swap the injector and see if the problem moves.

If this doesn't move the problem then you need to get the compression on the cylinder(s) measured.
If the previous steps haven't moved the problem I suspect you will find No.1 has a lower compression figure which suggests valves /piston etc type problems. If the compression is OK (and the misfire is hardly noticeable) then maybe the Misfire sensor or engine mountings are bad.

Finally I would also look for inlet manifold leak especially if the plug is dry. This is achieved using an oil can with a LITTLE fuel in it which is squirted around the inlet joint. THIS PROCEDURE NEEDS TO TAKE INTO CONSIDERATION THE ASSOCIATED FIRE RISK. ONLY USE THIS TECHNIQUE AFTER CONSIDERING THE RISK. Best left to somebody who is familar with this technique.

Problem with buying all new stuff is that unless it is MB original parts it is possible that you have made matters worse. However this is unlikely BUT has to be considered.

So where are you on my diagnosis tree?

Come back with your findings.

Good luck.

Stuart

 

Sorry not mentioningmy car specs, it is a 2002 E320 w/72k miles.I have notgot this problem fixed but this thread has been the most helpful. My mechanic mentioned that a faulty injectorleakingwas prolly my problem when replacing the fuel filter last week. It has been me personally buying parts and replacing them regardless not knowing the exact problem w/my car.I replaced the spark plugs first(Should I have changed the wires also? Mechanic said I didnt need to), replaced ignition coils next(Mechanic told me to only replace the 1 that was out but I personally wanted to change them all at the same time so I wouldnt have another 1 go out sooner than later and I got a deal getting all 6 of them at once,saved $150), and I replaced the fuel filter last. I need a Service B but from what I read I have already done the major stuff myself and find no reason to pay the dealership $400+ to do the same jobs and that not fix the problem. I am having problems finding a fuel injector for my car tho, any suggested sites that I cant seem to find? And should I not replace my Maf? The service records for my car werent recorded in the booklet so I have no clue what and how much work was done to my car.I appreciate yalls(Snanceki &Ohlord)
help very much.It seems that U 2 are the only 2 w/knowledge that responds in a decent time.Thanx.

 

So Plug No.1 is wet. Is this after you have been "messing" with the engine in the garage or after the motor is really warm and had a run on the highway?

NO NEED TO GO AND BUY ANY NEW PARTS YET!

Have you checked that there is a good spark at idle? To do this you will need to run the engine for a moment or two with the No 1 cyl spark plug lead fitted to spare plug suitable supported against engine block. You can leave the existing plug in No.1 although without any HT lead you will introduce a misfire which may...or maynot...make the existing misfire worse. this misfire won'y cause a problem at idle if only left like this for a minute or two. Any unburnt fuel going down the exhaust will make the cat work harder than normal.
Results?

If there is a good consistent spark you next need to check out the No.1 injector. Swap it for No.2 and see whether misfire moves as I described in my last post. Results?

What are the cylinder compression test results?

What sort of oil consumption are you getting?

When I have an answer to these tests we will consider next steps.

It is quite possible that No.1 injector is faulty but there is no need at this point to purchase new parts.

Stuart.

 

Everything
You got a vaccum leak. Look at the front (slight left) of the engine.

 

Stuart. Hopefully you can help me

I replace the spark plugs. I replaced one coil pack pack. I re-ran the test .