Has anyone gone through emissions lately? I went today and the 'Bird passed but the NOX was borderline. Anyone know what causes this? As for everything else is concerned it was blowing roses out the tailpipes.

 

Check for proper EGR operation. That plays a big part in low NOx readings.... Gimme a call sometime, Ill give you a hand with it. I just got my Chevelle through. If that passed, just about anything will.

 

I just sent both of my cars through. Both passed. But the T/A is throwing an EGR code. I guess the EGR valve has to be replaced again. What a pain, taking off the plenum.

 

Forgot to say, it's an easy job on the LO3. The EGR sits right on top. On the TPI engines it's under the plenum.

 

get the fel pro TPI gasket set the ROL set is junk but it's much cheaper

 

here's a dumb question... but... how do you check that?

 

EGR? HSRs don't have EGRs.

Went through 4 months ago. Just had to tweak the fuel pressure and the initial timing.

 

I don't remember who. He was going to school & it came straight from his school book.

Emissions failure & possible causes


Excessive HC emissions may be caused by:

ignition system misfiring
Improper ignition timing (retarted)
excessively rich air/fuel ratio
low cylinder compression
defective valves, guides, or lifters
vacuum leaks

Excessive CO emissions may be caused by:

rich air/fuel mixture
dirty air filter
faulty injectors
higher-than-normal fuel pressures
defective system input sensor

Excessive HC and CO emissions may be caused by:

plugged PCV system
excessively rich air/fuel ratio
stuck open heat riser valve
AIR pump inoperative or disconnected
engine oil diluted with gasoline

Lower-than-normal O2 readings may be caused by:

rich air/fuel mixture
dirty air filter
faulty injectors
higher-than-normal fuel pressures
Restricted PCV system
charcoal canister purging at idle and low speeds

Lower-than-normal CO2 readings may be caused by:

leaking exhaust system
rich air/fuel mixture

Higher-than-normal O2 readings may be caused by:
an engine misfire
lean air/fuel mixture
vacuum leaks
lower-than-specified fuel pressures
defective fuel injectors
defective system input sensor