Cregg Cowan <cowan@erg.sri.com> writes:
>Unfortunately, my beloved TR6 failed the California Smog test yesterday.
>It was close, but missed the CO% maximum by a small amount.
The '74 TR6 engine in my car also failed a month or so ago for the exact same
reason. CO% at idle was OK, but at 2500 rpm was 4.7% instead of the required
4.0%, and my EGR valve was declared inoperative. This was after it had earlier
been judged a gross polluter in a pre-test for which I had done no preparation.
After doing nearly everything listed in the "CA emissions" thread by Shane
Ingate, (new fuel and air filters, plugs, dist cap, rotor, condenser and set
the timing to the specified 4ATDC) it ran terribly. With the help of a
mechanic I traced this to a clogged vacuum retard line. He also adjusted the
mixture while reading out the emissions test. The end result, however, was the
over-max 2500 rpm CO% reading (done at another garage because unfortunately my
English sports car-savvy mechanic is not a liscensed smog technician). I had
also run through a can of "emissions reducer" in a tank of super premium
Chevron gasoline, but one thing I did not do was change the oil. Presently I
am replacing all the emissions, vacuum and breather hoses, along with the plug
wires, coil and evaporative absorption cannister. Just before the test I will
change the oil, first running some engine flush for a few minutes before
draining then putting in 20-50w. If it fails again I will rebuild the carbs.
>I assume this is adjusted by setting the trim screw on each carb (I still
>have the controversial ZS175's....), but I'm unsure what to set it to.
>Any advice from fellow California TR owners?
I understand from my reading (and not from hands-on experience) that it is
only profitable to adjust the trim screw on these ZS carbs if you have the
car attached to emissions measuring equipment.
We may complain about the bother of passing CA emissions, but I for one have
thus been strongly motivated to learn more about my car and get it running
better.
Still a lot to do before the air clears,
Richard Breedon
'74 TVR 2500M
'87 MB 190E (2.6l)
'87 Volvo 240DL (smogged last week at way, way under all specs)
'36 Ford V8 (sure glad this has no emission requirements)
|