I have just purchased a 1994 Z28, black, T-tops, 79k miles. Very well maintained by the previous and only owner. ($4,000)
I also have a 73 240 Z with a 94 LT1 and T56, and have TunerCat which I have played with a bit on the 240Z.

Well, my first problem with the car:
Failed emissions test!!
Failed on NO at the 15mph run (amost double the max). HC and CO were great. 25mph was great.
The P/O told me that the CAT was replaced in 99 and the car hasn't done much milage since. (I know him and he has no reason to lie)
My next guess is the EGR, or the O2 sensors. I picked up a pair of Bosch sensors, but haven't installed yet, The car was idling for at least 20 minutes prior to the test (as instructed by the tester). I have droppen in a bottle of 'guaranteed to pass' juice in the tank.

BTW...the tester could not get to the plug lead to get an rpm signal, so both tests show 825 rpm.

Any other suggestions? Would just lightly tapping on the EGR valve help (maybe it's a bit sticky?)

Thanks all!

Tim

 

I know this won't help your smog situation, but I've heard quite a few people say that the Bosch O2's are not very good. You may want to see if you can return them and go with some AC Delco's.

 

Just to close the loop:
Replaced the O2 sensors (unnecessary, I'm sure), dropped some denatured alcohol into the tank, and retested.
Passed with flying colors!!!!

Tim

 

Welcome to the board.I am glad you passed the test.

 

How much denatured alcohol did you put in?

I have get my car smogged and have some concerns this time about passing smog.

 

I ran some of the 'Guaranteed to pass' product from CRC industries (from Pep Boys) in half a tank of gas. Ran the tank down, then put in some 91 octane (which I always do), and 10% alcohol (put in 5 gallons of gas, and 1/2 gal of alcohol).
Went straight from the smog station and filled up the tank.

Tim