Failed Ca. Smog test
Intermediate
Joined: Jul 2018
Posts: 46
Likes: 2
From: statesville,north carolina
id do the first things first, ignition tune up, plugs, plug wires, rotor, rotor cap. Once all that's known to be good, you can start chasing other things.
like 02 senores ???
if u got a maf senor ?
temp senor ?
that's the first things I would have looked at
Last edited by skinnyt; Dec 27, 2018 at 09:28 PM.
Pro
Joined: Mar 2000
Posts: 690
Likes: 7
From: Bradenton, FL
Cruise-In II Veteran
Your blm of 151 shows the car is on the edge of being too lean. That will raise combution temp and nox. Assuming your egr is clean and working correctly, verify your fuel pressure is at spec (too low will cause a lean tendancy). And verify that the base timing is at spec — too much base advance will drive both hc and nox up.
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 196
From: folsom california
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Replaced the egr valve , egr solenoid, and egr temp sensor. Put a new cat on. Still failed emissions due to high NOX. Ran a scan on my vette today. Its going into closed loop. Rich Lean flag goes rich/ lean. Cross counts 171, Block learn 151. The engine runs good. Still haven't checked plugs. EGR duty cycle is working. Seems like I have weak vacuum though. Any suggestions?
You might want to look up what type of EGR valve your model/year has. Positive backpressure, negative backpressure or just straight vacuum operated EGR?
Oh and something to look at is your tune as a leaner running engine makes more NOx but less HC and CO. Look at the emmisions graphs for fueling and you will see it's a tight operating band to keep all 3 emissions products low. So you might want to consider a slightly richer tune if you are lean at all now.
Just FYI I have been reading that California emissions have been getting tighter even for older cars meaning that the standards today might fail a car that passed previously.
Let us know more about your car if you still want help.
