Another 1991 Fails CA emissions... Help!

[Shinto]

Originally Posted by gbrtng

The audible pinging is a clue - it's running lean with advanced timing. Maybe a failing injector or knock sensor. What gear do they run the 15 and 25 mph in?

I'm not sure what gear, as the test is about as hands off as it gets. I'm not allowed in the service area. That's why I gave the listed rpm (I'd guess 2nd).

Originally Posted by gbrtng

Also, has CA lowered the NOx limit recently?

It's against federal law for them to change the limits for the model year car to be lower than what was originally approved, but it wouldn't surprise me if they did. They keep making the testing increasingly hard to pass and thinking up new ways to fail cars. They actually pressure tested the GAS TANK in the '78 Trans Am and failed it on that (as well as other tests).

This last go round the smog machine actually gave NO feedback to the operator in terms of emissions -- only rpms and speed. We didn't know it failed until the test was over and it printed out.

I also see more and more data printed out every time I have a test done, regardless of model year. (Ask me what I REALLY think of this in an uncensored forum... Starting to remind me of a certain country in Europe in the late 1930's...)

How do I test the knock censor and injectors?