Update on Emissions / Cat
Thread Starter
Burning Brakes
Joined: Aug 2002
Posts: 926
Likes: 2
From: chandler az
Update on Emissions / Cat
Well I passed my test but I am still concerned.
I replaced the Center cat with a new one
here are the results:
My Reading today /Second test / First test / Allowable
HC 0.10 / 0.31 / 1.16 / 1.60
CO 0.43 / 4.65 / 6.49 / 15.00
NOX 2.40 / 2.63 / 2.57 / 2.50
It helped big time on the HC and the CO but not the NOX. I am guessing that the new cat is not a 3 way cat? Someone had mentioned that the EGR was probably not functioning correctly - wouldn't I get a code 32? Wouldn't a lean mixture show up in the HC/CO readings? Would a scanner give any information that would help me diagnose this?
Thanks for any help you can give me.
I replaced the Center cat with a new one
here are the results:
My Reading today /Second test / First test / Allowable
HC 0.10 / 0.31 / 1.16 / 1.60
CO 0.43 / 4.65 / 6.49 / 15.00
NOX 2.40 / 2.63 / 2.57 / 2.50
It helped big time on the HC and the CO but not the NOX. I am guessing that the new cat is not a 3 way cat? Someone had mentioned that the EGR was probably not functioning correctly - wouldn't I get a code 32? Wouldn't a lean mixture show up in the HC/CO readings? Would a scanner give any information that would help me diagnose this?
Thanks for any help you can give me.
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
High NOX levels are due to high combustion chamber temps which the EGR valve helps reduce. The EGR passages in the intake manifold could be carboned up and need to be cleaned out. You can also check and replace the EGR temperature switch and the EGR solenoid.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
yup... EGR is at fault.
It may be bad porting, or even a leak in the line. The valve may not be opening correctly, or letting in too much fresh air.
Either way, an EGR can function incorrectly and still not throw a code.
BTW, Cats, of any kind, won't fix NOX.
It may be bad porting, or even a leak in the line. The valve may not be opening correctly, or letting in too much fresh air.
Either way, an EGR can function incorrectly and still not throw a code.
BTW, Cats, of any kind, won't fix NOX.
Racer
Joined: Aug 2004
Posts: 379
Likes: 170
From: Buffalo Grove IL
Originally Posted by bogus
BTW, Cats, of any kind, won't fix NOX.
I'm surprised your NOx readings are as high as still are, I would have suspected a new converter would have reduced the NOX levels further. I can't believe they wouldn't have replaced it with an old two-way converter, since three-way converters have been common for 20 years now. Kinda odd...
EGR is the other main defense against NOx, so I agree with the others, it seems like it's not working correctly. A lean mix could also raise NOx somewhat, but as you mentioned, based on your CO and HC levels, I don't think you're running lean.
Btw, congrats on passing the test!!
Ben
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