Dan V

Here's some possible causes of high HCs:

http://www.smogtips.com/failed-high-hydrocarbons-HC.cfm

tj90

Thanks for the list. Interesting read. Plenty of things Id check before rebuilding the motor.

I was also interested in reading that lean conditions cause high HC. What?!

BTW, sometimes rarely I smell sulfur - It may be coming from me - I sure hope not! If it is, my cats are going... Damn, sometimes ignorance is bliss! Maybe I should upgrade to 100 cell cats. Will 100 cell cats compromise CA emissions?

thechief

Here are the complete numbers from the first test, the first number is the max allowed and the second is measured amount:

15mph test- CO2 13.70, O2 1.18, HC 85/68, CO .50/.10, NO 695/60
25mph test- CO2 14.00, O2 .72, HC 50/56, CO .47/.21, NO 717/196

The test sheet doesn't give a max number for CO2 nor O2, but the technician told me that the CO2 value represents burned fuel and the HC represents unburned fuel. So I passed at the 15mph, but failed at the 25 mph test.

Less than a thousand miles ago my diferential imploded, so when I had that repaired I also did the 90K service and all that entailed including plug wires a distributor drive belt. The O2 sensor has I would guess about 12K miles on it sense replacement, as far as I know it has the original cat.

That's a clever take on the gasoline, I hadn't thought of the problem in those terms. If the chemicals and "Italian tuneup" don't work I might as well give that a try. Or anyone have a gently used catalytic converter for sale?

tj90

At the very minimum, verify that all your plug wires are seated on the plugs, all vacuum lines are connected - there are alot of those things running all over the top of the engine. Hopefully something was bumped loose or wasnt assembled properly at the 90k service. By the way, did you get your distributor cap parts/belt replaced as well? Want to make sure you are getting plenty of spark to BOTH plugs in each cylinder. It that belts broken, you could be firing only one plug...

Also, I believe CA will pay for the car to be inspected and repaired if it fails emissions. I dont think Id want one of these guys looking at the porsche, but you may be able to get parts out of the deal?

thechief

Well it passed. Over the weekend I drove up to the Santa Monica Mountains with a full tank of gas containing a can of Jectron and a can of Ventil Sauber and spent all afternoon going East to West and North to South and back again.

Next day CO2 was up, O2 was nil, NOX was way down, and most importantly, HC's were well under the limit. I now have a two year reprieve to fix the problem, which at this point I believe to be a weak catalytic converter. We put the car on a lift and read the temp on the cat and my technician said it was pretty low. So we found a pretty long hill and drove up and down it a couple of times to get it as hot as possible, but it was a cool day and the temp gauge never got over the first hash mark, but it was enough. In addition, for the last year I've noticed a slight vibrating noise on start up and when disengaging the clutch in first and reverse, I now think this noise is coming from the cat. Judging from the clamps and the condition of the cat itself I'm sure it's the original part. At 90K, the valve guides are surely worn as well, but I'm not anywere near the 1 qt of oil per 600 mile level yet, still something to look forward to, however.

I'd forgotten how much fun those roads from Augoura Hills to Malibu are to drive. Need to be very mindful of oncoming motorcycles, however. Speaking of which, stopped at the popular Rock Store, about 100 motorcylces of every persuasion parked in the lot, quite a show. I guess the Highway Patrol saw it that way too, there were three on them in attendance issuing citations for I don't know what. I had recently replaced my busted diferential with a Guard Transmission torque biasing unit, what a great upgrade. That along with the lowered European springs and HD Bilstiens made for a very enjoyable afternoon, although we had to stop after a couple of hours because I made my wife car sick. Thank you one and all for the helpful suggestions.

tbil

Congratulations on passing! Good advice here always helps, thanks for sharing the experience.

tj90

Awesome update. Glad to hear that you got it sorted out. Sounds like the HC reduction could be due to the can of Jectron and a can of Ventil Sauber.

I wonder if 100 cell cats could be your upgrade path and still stay ca compliant?

Chuck W.

Good deal. I live in Agoura Hills. You were in my back yard.