Engine misfiring and not accelerator properly

UJELOUJELO

MEMBER
2002 MERCEDES BENZ C240
3.2L
V6
2WD
AUTOMATIC
80 MILES

Greetings to everybody. I have a problem with my car listed above w203 c240. When I start it, it struggles to accelerate for some minutes around 10 minutes after that it will start responding when I press the gas pedal at this point it will be in park when I put into drive or into reverse it won't accelerate again but if I put it in park or in neutral it will respond and rev. So, I hookup my laptop to scan it it's showing misfiring on cylinder 1, 2 and 3 and showing about catalytic convertors and O2 sensor it's not talking anything about throttle body or accelerator pedal sensor.

So, what I have done for now on misfiring I bought all twelve spark plugs and I have swapped my coil packs for cylinder 1, 2 and 3 I put them on cylinder 4, 5 and 6 but the misfire still stays on cylinder 1, 2 and 3. Any help please will be appreciated. I Don't know if clogged catalytic is causing the misfiring. Please help. Thanks in advance.

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

If the misfire is staying on the same bank, have you checked fuel pressure? Also, are you able to provide the codes you found and short-term fuel trims?

I looked up a 2002 C240 and its indicating a 2.6L V6. Please confirm that for me.

Take care,

Joe

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Sunday, November 7th, 2021 AT 7:15 PM

UJELOUJELO

MEMBER
2 POSTS

Thanks for reply I have uploaded the video showing when I scan on fuel trim its shows 25% on short term bank 1 and short-term bank 2 then on long term fuel trim bank 1 and bank 2 it shows 0%.

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Sunday, November 7th, 2021 AT 9:17 PM

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

Did you upload a video? If so, it isn't showing. Regardless, if you have a positive 25%, that is high. It indicates the car's computer is adding fuel (more than normal) to the engine to compensate for a lean mixture.

Under normal conditions, trims should be between -10% and +10%.

Question, the trims you provided, was the engine at operating temperature? Also, the 0% LTFT was the vehicle driven?

Let me know. Also, based on what you provided, I would check fuel pressure and for engine vacuum leaks. Here are two links you may find helpful:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

One last thing. Please confirm the engine size for me and provide the codes that were retrieved.

Take care and hang in there. We'll get it figured out.

Joe

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Monday, November 8th, 2021 AT 4:59 PM