High Knox
 

Hello everyone
Newbie here
280ce California edition failed smog high Knox
Replaced cat and egr failed again high Knox
Any ideas ?

too lean.

Yes too lean
Smog guy said maybe the two cats of the exhaust manifold need replacement
Dos that make sense ?

too much air, not enough fuel. you need to adjust the fuel-air mixture. how are the spark plugs, distributor, rotor, and wires?

New plugs wiers cap and rotor air filter fuel filter
How to get the reading on the air and fuel mixture myself?

If you can run half e85,and gasoline for the test only

What year 280CE? Make sure EGR is functioning properly. All new parts won't work if the vacuum signal isn't getting to them. If EGR checks out and you're good on HC and CO, you probably are a bit lean. What do the other numbers look like? Also check ignition timing. Too advanced will give you higher NOx.

I used to work in a shop that tuned older German cars to pass smog. We had an exhaust gas analyzer. It's tough to get a reading on fuel/air mixture without one unless you have a new enough car to have an O2 sensor, which I'm pretty sure your car won't have.

One other less likely possibility is abnormally high compression due to the pistons being carboned up from prolonged light use. Italian tuneup will help with this. Even if it doesn't help, it's still fun to do.

Egr checks good
Hc and co numbers below average
The car is 1978 no o2 sensor
What's Italian tune up ?

The car was at German repair shop
The guy said egr not working and wanted 600$
I get egr from mercedes and installed it for 300$
Nothing changed on the smog numbers

How did you check the EGR? No change in numbers indicates no change in function, so either it wasn't working then and still isn't, or it was working fine to begin with.

An Italian tuneup is when you take your car out and run it hard for a few miles to get everything hot and dislodge built up carbon in the cylinders that can come from not being run hard.

Im going to retest the egr system based on the chilton manual
Again and see

Italian tune up sounds good though