Trying to pass CA smog check and stumped!

Sacto S · 04-07-2011, 03:00 PM

I had my car tested the first time and it failed badly due to the fact that it was running VERY rich. OK, took it in and the shop made some adjustments. Took it in for a second test. Failed again and still running very rich

. Back to the shop for more tinkering. A new cat was installed and they have been sorting through things but still unable to get the car leaned out enough to pass. It is fine when at idle but as soon as it is placed under load the thing reverts back to running very rich. ANY IDEAS??? ALL HELP GREATLY APPRECIATED!!! Thank you!!!

Stock 1980 911 SC

911Freak · 04-07-2011, 03:23 PM

Has the engine been maintained?
When was the last tune up (Plugs-cap-rotor-timing-valve adjustment etc)

Are you driving the snot out of it prior to the smog test? I drive my 81 SC nice and hard for about 30-45min and drive into the smog shop and leave it idling until they take it in for testing. The entire time they have the car its running.

If the engine is not up to normal temps it will read rich on the test.

If all of the above are present and accounted for I would suggest reviewing the ultimate CSI thread here, get your CIS gauges and start taking pressure tests. You may have a piece of the CIS system malfunctioning and these tests will shed light onto any weak links in your system.

I also might think about taking it to a different mechanic... I do all my own work, but before I did I used a mechanic that would pre-test my engine before I ran it down to the smog shop. Your mechanic should have run the CIS system pressure tests. My guess is he leaned out the mixture on your fuel distributor and sent you on your way. IMO that's not good enough. YMMV

Good luck and my advice is do not have it officially tested again until you know for a fact it is running properly and will not fail the 3rd time and be flagged as gross polluter!

Peter Zimmermann · 04-07-2011, 03:57 PM

Quote:

Originally Posted by Sacto S

I had my car tested the first time and it failed badly due to the fact that it was running VERY rich. OK, took it in and the shop made some adjustments. Took it in for a second test. Failed again and still running very rich

. Back to the shop for more tinkering. A new cat was installed and they have been sorting through things but still unable to get the car leaned out enough to pass. It is fine when at idle but as soon as it is placed under load the thing reverts back to running very rich. ANY IDEAS??? ALL HELP GREATLY APPRECIATED!!! Thank you!!!

Stock 1980 911 SC

Your car was built with a three-way catalytic converter that incorporated an oxygen sensor and a test port from which to take an exhaust sample for test purposes. Was your cat replaced with an o.e. unit? Is your OXS/Lambda system functional? When your shop set the CO%, what was the spec they used? This job does not require "tinkering," it requires a logical approach as to why this is happening.

Does your shop know that CO adjustments must be made pre-cat, everything else is just a guess? Does your shop adjust your car at operating temperature with the front oil cooler hot to the touch and idle speed at 900 +/- 50 rpm? Does your shop know that the oxygen sensor must be disconnected to set the CO, and then re-connected for the smog test? Does your shop know that the CO% spec is 0.4 - 0.8? More info, please.

eastbay · 04-07-2011, 04:07 PM

post up the test results so we have something to work with

Porsche 911 · 04-07-2011, 05:19 PM

Were Pin 10 wires connected beneath the driver's seat

feelyx · 04-07-2011, 05:51 PM

Which shop are you using?
Tim

Sacto S · 04-07-2011, 06:31 PM

Tinkering was a poor choice of words. The shop is sorting it out step by step. Just haven't gotten it figured out at this point. I'll pass along these ideas.

Joe Bob · Joe Bob's Garage

Tinkering w/o an exhaust analyzer attached and you are paying them? Ahem.....hope you used a credit card and have entered a complaint in with the BAR.

Use the test results and tell the NEXT shop you go to that you need to fix what's on the sheet from the smog weenie.

If they don't use a long allen key to adjust mix.....they are just stroking you....

Quicksilver · 04-07-2011, 07:16 PM

Quote:

Originally Posted by Porsche 911

Were Pin 10 wires connected beneath the driver's seat

That is for a Motronic car (84 and later). An 80 is a CIS engine. That is a different machine.

Quicksilver · 04-07-2011, 07:20 PM

Off hand I can't remember hearing of a great Porsche shop in Sacramento. The CIS machines really should be taken to someone with great experience in the system. The bay area isn't that far of a hop and there are some great shops over there.

Besides, the drive is worth it just for the food!

Alan Lindquist · 04-07-2011, 09:28 PM

Sorry it seems complicated. I'm going to contradict some of the above questions based on experience, not knowledge. I have a 1980 SC. I run a cat bypass. When it is time for smog, I swap the bypass pipe for the Cat that was on the car 100,000 miles ago. I do most of my own maintenance and repair, but I use a local mechanic for smog and some emergency repairs (it's a daily driver). My mechanic has a business based on air cooled Porsche. I've seen a few water pumpers at his shop, but he swears they are loyal air cooled guys with "another car." Whatever. He leans the mixture on my car. It BARELY runs at that point. HE drives it to the nearest smog station and it passes with flying colors and HUGE margins. Then he drives it back and re-adjusts it for daily driving. That's it. I pay him for his time and effort and go home and swap the cat for the bypass pipe and do it again two years later.

The cat (I'm not an engineer or scientist) needs to be functional. My car burns oil. I have 220,000 mile on it and to my knowledge, the motor has not been rebuilt. I'm thinking that the cat is "fresher" because it doesn't live day to day with the blow-by oil building up. Let's assume that the cat needs to be accounted for - if it is not in good condition, no amount of tuning will help.