1992 400E - high HC at idle?
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Junior Member
Joined: Sep 2008
Posts: 32
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From: Dallas, Texas, USA
2004 SLK 230, 1992 300E & 400E
1992 400E - high HC at idle?
RPM @ 2483 = 173 PPM. THE ALLOWABLE 1S 220 PPM @ BOTH RPM's
RPM @ 638 = 393 PPM.
I just purchased this car, changed the oil and filter and air filters, installed new plugs (Bosch), replaced the O2 Sensor (Bosch OEM), ran a can of Sea Foam thru the gas tank and took it by the inspection station. I drove it home to Dallas from Maryland with no problems whatsoever. It has 168K on the clock.
It still has SeaFoam in the tank, but that wouldn't cause the problem, would it?
I did notice when I installed the new O2 sensor that the Cats (two of them side by side in the exhaust system and I don't know if that is what is called the PRE-cats or not?) anyway, they looked as if someone had taken them apart at the seams and re-brazed them back together (suspicious shiney new grinding marks at the seams around the total circumference kinda led me to think this....).
Anyone with any suggestions?
Would a couple of gutted-out cats (or pre-cats) cause this high HC reading?
RPM @ 638 = 393 PPM.
I just purchased this car, changed the oil and filter and air filters, installed new plugs (Bosch), replaced the O2 Sensor (Bosch OEM), ran a can of Sea Foam thru the gas tank and took it by the inspection station. I drove it home to Dallas from Maryland with no problems whatsoever. It has 168K on the clock.
It still has SeaFoam in the tank, but that wouldn't cause the problem, would it?
I did notice when I installed the new O2 sensor that the Cats (two of them side by side in the exhaust system and I don't know if that is what is called the PRE-cats or not?) anyway, they looked as if someone had taken them apart at the seams and re-brazed them back together (suspicious shiney new grinding marks at the seams around the total circumference kinda led me to think this....).
Anyone with any suggestions?
Would a couple of gutted-out cats (or pre-cats) cause this high HC reading?
MBWorld Fanatic!
Joined: Dec 2006
Posts: 1,907
Likes: 2
From: So Cal
92 500e, 95 E34 525I Touring
I had the same issue with my 500E recently. Refurbished cap and rotors did nothing.
I replaced the convertor, and everthing was right again. The old one was falling apart inside and definitely was not doing it's job.
I replaced the convertor, and everthing was right again. The old one was falling apart inside and definitely was not doing it's job.
