davidon
Well-Known Member
Failed the HC part of the emissions test (barely). Cat is fine. CO test if fine. Would a cracked exhaust manifold cause this? Any other stuff to look at?
Emissions fail (Car)..suggestions?
- Thread starter davidon
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twistedmax
Well-Known Member
How long did it run before you brought it through?
overzat
Well-Known Member
engine light on ? spark plugs old?
RaWarrior
Well-Known Member
Take it to a different inspection station. Calibration variances in those sniffer machines can be pretty large.
High HC can be from a few things. Most common are a bad cat(or the air pump system that feeds it fresh air is broken), or a too-lean fuel mixture. I've heard of a bad O2 sensor telling the ECU it's too rich, and the engine makes itself too lean and gets this error. My old truck did this and the check engine light would randomly go on and off with a "o2 sensor out of spec-rich" code.
Its fundamentally caused by a poor fuel burn. Weak/intermittent spark or low compression can also cause this.
High HC can be from a few things. Most common are a bad cat(or the air pump system that feeds it fresh air is broken), or a too-lean fuel mixture. I've heard of a bad O2 sensor telling the ECU it's too rich, and the engine makes itself too lean and gets this error. My old truck did this and the check engine light would randomly go on and off with a "o2 sensor out of spec-rich" code.
Its fundamentally caused by a poor fuel burn. Weak/intermittent spark or low compression can also cause this.
davidon
Well-Known Member
About 15-20 min. I've never changed the O2 sensor and its a 93 so could be that as well. Limit is 175ppm and I think i pulled a 225.
