From:
markrock_REMOVE_497829_THIS_@yahoo.com
Wendell
In our experience, once the basics Duke mentions have been ruled out,
you are left with two other possibilities. One is the catalytic
converter. It is possible that a new converter will do a better job
of converting the unburned HC's.
On Dan's Cosworth, we had a similar problem. What I did was borrow a
friend's Exhaust Gas Analyzer, stuck it up the tailpipe, installed a
spare MAP sensor, and adjusted the MAP sensor to give the best
readings. I would have left in in place, but the car didn't run very
well that way, so after the test I removed it and put it on the shelf
to be reinstalled the next time a test was due. Finally I was able
to license his Cosworth as a Collector Car and no longer needed to
pass the test.
We had a similar problem with Ken's Cosworth as well, but it had
Webers. We had to change the idle jets in order to lean the mixture
sufficiently to enable it to pass.
The only other realistic possible solution I can think of is to
change the fuel in the tank when testing occurs. Someone, perhaps
Duke, once mentioned a product sold in Europe that has remarkably
clean burning properties. I've never seen that product here, but
there ought to be something that would burn cleaner. My two tricks
were to use premium gasoline, and to use a gasoline containing the
maximum allowable amount of ethanol. Whether those really worked or
not I cannot say scientifically, but that is what I did.
I must admit to having considered laying my oxygen bottle in the back
and running a hose through the firewall and into the mouth of the air
cleaner--they don't open the hood in Ohio--then cracking the valve as
I pulled in for the test. I figured I could get more complete
combustion that way, but never got desperate enough to try.
Mark
[This is message #10238 by user markrock on Yahoo! Group Cosworth Vegas:
http://groups.yahoo.com/group/cosworthvegas ]