1999 C-Class W202 Misfire Issue

[NotePapa]

Greetings everyone,




Vehicle Information Model: C-Class C180 Year: 1999
Classification: W202
Engine Model: M111.921

I acquired a C180 earlier this year. It has been functioning well for many months; nevertheless, it has just encountered a little difficulty. In recent months, when I attempt to drive with a cold engine, the automobile jerks as if it had no power at all. It exhibits no acceleration, as if it is not receiving any gasoline. The only method of operation is accelerating from 900rpm to 1500rpm, thereafter shifting to the next gear, and continuing this process until the desired road speed is attained. However, if I start the vehicle and let it to reach a temperature of 90 degrees before using it, its performance is often satisfactory.

Additionally, along with the aforementioned, another difficulty occurred. While operating a vehicle on motorways, it sometimes experiences a loss of power at around 70-80 mph. The power loss is brief and may be restored within seconds by withdrawing the accelerator and thereafter pushing it down slowly and carefully.

The vehicle seems to be significantly underpowered. I recognize that it is a substantial vehicle, although I strongly suspect that it is not delivering its full power potential.

I originally neglected the problem since I was aware that the automobile required servicing soon. Last week, I had my father take the vehicle for servicing and its MOT at a family friend's garage. It successfully passed the MOT inspection. It was also serviced and connected to the Mercedes Star Diagnostics system. The technician informed my father that many cylinders were misfiring. He addressed it and said, "It is satisfactory now." I assume he replaced the spark plugs. As a family friend, I was paid a little fee for the services rendered, hence I have no grounds for complaint. The garage is very far, and returning incurs significant expenses for me.

My uncle, an exceptionally skilled mechanic, and I convened over the weekend. He informed me that I should replace the plug leads, since the automobile exhibits signs of misfiring, and the leads seem to be the likely cause. Upon examining the engine, I was unable to locate any conventional plug leads. I returned my uncle's call and elucidated what I seen. He then recommended that I get one Ignition Coil Pack and substitute it for one of the current units. If I see a discrepancy, I should regard my issue as resolved. He said that if the issue persists, I should reinstall the original coil pack and sequentially replace each subsequent one until I locate the defective pack or packs.

He said that they are rather simple to interchange. I attempted to identify the packages. I was unable to determine their location and the means of accessing them. I am not inept and have previously maintained my older vehicles with proficiency. This is my inaugural Mercedes, and I am currently out of practice. I have attached images of my engine and would appreciate any advise, instruction, or assistance you can provide.

Thank you very much

[NotePapa]

🥰

[Lemmand]

It seems that the mass air flow sensor may be malfunctioning; several discussions here reflect the symptoms you are encountering.

[Lemmand]

https://www.ebay.co.uk/sch/i.html?_nkw=mass air flow sensor&campid=5338181132&customid=2518X1570512X2a6122443e920827fe4a84c7d8026150&mkcid=1&mkrid=710-53481-19255-0&subId2=15&toolid=10001

[Messand]

This is a well recognized issue with these vehicles. There are two coils, each activating two cylinders/plugs. They are situated behind the plate above the cylinder head cam cover. It is secured by three or four Allen/Torx-headed bolts. It is necessary to detach the cross engine intake pipe. Upon removal of the plate, the plug leads and coils will be clearly visible. Any of the components may be defective, including the low voltage wire from the engine ECU, which often fails due to elevated temperatures from the engine. Numerous postings and images about the subject are available here; it is advantageous to peruse them.

[Messand]

This pertains to an SLK, however the same ideas are applicable.

[Messand]

http://www.benzworld.org/forums/atta...y-1999-slk.pdf

[BeardAndBeans]

Greetings,
When replacing the ignition leads, note that there are only two, and remember to also replace the plug covers located under each coil.

[NotePapa]

The PDF link seems to be truncated and is nonfunctional for some reason. Could you please repost the link for me? Thank you once again.

[NotePapa]

I believed it may be associated with it.

[Messand]

Refer to post #38 in this thread for the link.

[Messand]

http://www.benzworld.org/forums/r170-slk-class/1289594-tech-tips-such-4.html

[NotePapa]

Outstanding! Extremely helpful! Thank you, Grober. You are exceptional!

[NotePapa]

😇

[GravyRocket]

I had a similar issue with my vehicle and changed the air mass sensor; since then, I have seen no problems. I recommend you consider this as a preliminary, cost-effective solution.