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S-Class (W140) 1991-1999: 300 SD, S 350TD, 300 SE 2.8, S280, 300 SE 3.2, 300 SEL 3.2, S320, S320L, 400 SE, S420, 400 SEL, S420L, 500 SE, S500, 500 SEL, S500L, 600 SE, S600, 600 SEL, S600L, 500 SEC, 600 SEC

CL500 Misfire - Diagnosis

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Old Aug 14, 2013 | 07:02 PM
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69 280SL, 92 500 SEL, 98 CL500
Question CL500 Misfire - Diagnosis
CL500 98
150k miles
Been garaged and maintained - I'm 2nd owner for last 9 years.

Issue: Misfire
OBDII Codes:
PO155 (O2 Sensor, RBank, PreCat)
PO303 (misfire Cyl 3)
PO307 ( " Cy7)
PO300 ( " random)

Pulled all 8 spark plugs - all look great - clean - perfect

Replaced all 4 O2 sensors (design lifetime)

Still misfires - with flashing Check Engine light - meaning gas being dumped into the cats with potential cat failure.

Acts like bad injectors on 3/7 but no other error codes?

Thoughts? Ideas? Suggestions? Insights? Accusations? Visions?
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Obd scanner help please

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