manpoole

I had a CEL which registered as a misfire in Cylinder 1. I have since done an italian tune-up and bought some techron. The engine seems to be running fine, although the CEL did scare me a bit. I had the code removed it has not since reappeared.

What could be the cause of this and what should be the first steps taken?

My car is a 2005 C230K with 80,000 miles M271 Engine.



On a side note, I also have a low coolant temp CEL.

LILBENZ230

If the engine is running too cool it can cause other issues like lean conditions, possibly this. Replace your thermostat - it's cheap and easy.

seagel1000

I don't think a thermostat would do this. I HAD to replace my thermostat but my code wasn't a Bank 1 misfire (Cylinder 1). It was something along the lines of a "too cold start up". Now.. I have gotten a mis Fire on Cylinder #1 before RIGHT AFTER doing a fuel filter change (and during the process, i purged the fuel system pressure with the little pin push in button to release pressure off the system, that is located under the cover where the spark plug wires are). My car hesitated to stay on after doing the filter change but after turning it on for the 2nd time and clearing the code, the car never game me the CEL code for Cylinder 1 mis-fire again.

My thread on the thermostat, look for the other thread where it shows you where its at and how i did it for reference

CLICK ME

Chris

LILBENZ230

The thermostat is a P0128 code about the engine being unable to reach operating temperature. I'm well aware of this and I didn't say that a bad thermostat would cause him to get a misfire code. An engine that can't reach optimum temperature can run a bit funny, and it IS possible that these two could be related. He needs to replace the thermostat since that is established as a problem and go from there. We had a member not long ago have a M271 giving a "too lean" code in conjunction with the 0128 and replacing the thermostat fixed both issues.

manpoole

Ok looks like I will be replacing the thermostat.... hopefully its easy... I'll probably get it from autohausaz.com

It just so happens I did replace the fuel filter 3000 miles ago and when i started the car, I forgot to leave it in position 2 to prime the fuel pump, and it ran funny and threw a CEL I just turned the car off, and the light went away...

I wonder if that particular Cylinder 1 Misfire CEL was from changing the fuel filter and it was still stored in the OBD II database... and the CEL that came on just the other day was only the thermostat??

Would it be wise to clean the MAF sensor and check the plug and coil pack or would that be unnecessary?

Johnsct

I got the same CEL. Changed the plugs (they were due, 119,000 miles) and the light went off after 2 days. Been of for about a week now. Had the low coolant temp at the same time. I didn't do anything about that but the light still went off on its own. I may need to change the thermostat also.

Glyn M Ruck

Check plugs, wires, coilpack. Change that thermostat. Dead easy.

importz_

this had happen to me awhile back but i had extended warranty and they took care of it for me otherwise i would have paid a fortune at the MB dealer here in houston

jokerswld34

was your car sputtering when the CEL came on? i got the misfire cyl 1 code a few months ago and then shortly after, the car started to bog and sputter. After shutting down, turning back on and clearing codes, problem seemed to go away. Happened again a few days later, so I pulled the plugs and coils to find cyl 1 spark plug fouled and the coil pack to be bad. I would advise that simple check right away and to change all the plugs. Most likely is the coilpack though...

I also replaced my thermostat around the same time, as my coolant temp gauge was reading very low even after driving the car for a while. the thermostat had nothing to do with my misfiring.

LILBENZ230

How many miles are you at now?

manpoole

80,000 miles I got the car CPO at 40,000 miles not sure if they changed the plugs and coil packs doubtful... how exactly do I check the coil pack? What do i need to look for?

I think I am just going to change the spark plugs out since they are cheap and easy.

aecasasus

Funny...I have had the same problem for about a week now. Yesterday I cleaned the MAF sensor and it runs smoother but the problem hasn't gone away. I ordered the spark plugs and I will possibly order the coils as well. I have been thinking myself that a coil is bad or something. We'll see...

Good luck with your fix. Please let us know how it goes!

manpoole

I am leaning more and more towards thinking the misfire code was a result of changing the fuel filter and not primming the fuel pump 3000 miles ago because i did get a CEL then and maybe thats what the OBD II scanner read. I will check the plug and coil pack regardless but I have no idea what to look for in a bad coil pack?

and jokerswld it did sputter pretty good and through a CEL the first time i started it after changing the fuel filter, it frightened me a good bit to say the least, although after i turned off the car and the started it again, all was fine.

Glyn M Ruck

The only way to check coil packs if you don't have a new spare is to swap them to another cylinder & see if the misfire code changes cylinder.

Buellwinkle

Single cylinder misfires are pretty common on the M271 motor. If it's not the obvious spark plug/wire/coil pack, then do a compression leak down test and see if the exhuast valve is cooked. If so, just replace the head and you are good to go.

fwwong

Guys,

I had the same problem. In fact, mine was misfiring of 2nd cylinder. I changed my spark plugs and coil as well. It doesn't help at all.

The actual problem is due to:

1. Top cylinder is extremely dirty. Solution: Top manifold block overhaul is required. This cost heaps of $$$ to do so.

2. One of the piston could have been dented and caused the small piece to move around within the engine block. So, the moment when we accelerate, that piece of thing might stick with one of the engine cam and trigger the misfiring issue. However, when we shut down the engine and power up again, this piece of metal might have dropped some where else until it hits the cam again. Then, the misfiring will come back again!

My current mileage is 90,000km+ Sigh..................

Buellwinkle

I think dirty valves is becoming more and more common with many new design engines as they strive for better fuel economy and better performance. Want to see valve getting dirty issues that cause misfires, checkout the VW/Audi forums, very common and even more so with direct injection because there's no fuel touching the valves to keep them clean. Also, my GMC Canyon has a 100K mile warranty due to valve issues they discovered, but at least GM admints there's a problem and has a remedy, MB and VW/Audi just stick their heads in the sand and make it a customer issue.

Glyn M Ruck

With DI engines Benz have detergeant injection on latest models which is topped up at service in Europe. US will not get these engines until fuel is improved & sulphur content lowered so that they can run their 3 way Cats which produce carcinogenic benzines at the tailpipe with high sulphur fuels such as the US has.

Early M271 engine head problems were caused by poor fuel. The engine was designed to run on narrow cut Eurograde fuel. Benz redesigned the head on the M271 for poor fuel markets like the US & SA. Newer M271 engines do not display this problem at all. Running your vehicle on Techron will help as will high RPM now & again to blow off the carbon.

VW/Audi & Porsche have big crap in the US with their DI engines.

Here is an M271 running on US fuel plus Techron - note deposit where fuel does not get.



Here is a low mileage DFI Cayenne's intake - deposit is oil coming down the guides, captive crankcase ventilation crap & fuel.