Failed smog, need some help
 

1983 911

Well technically I passed the smog, what I failed was the "functional EGR"

All the numbers were well within tolerance, but the failure was:
Need to reset engine RPM. Specs call for 900 +- 50 RPM and is at approx 1100
Need to reset ignition timing after RPM is corrected. Timing is too far retarded - spec calls for 5 +- 1 BTDC @ 900 RPM +- 50

First off - small rant:
Who the heck CARES what the timing and RPM is at if it PASSES the smog numbers? Even the mechanic said it was stupid.

That being said - what now? If I lower the RPM and advance the timing will that make the smog numbers fail?

Thanks all,
Andy

I was told a hotter engine burns cleaner, and ignition advance raises HC's faster then retard. They check the rpms so people don't tweak the idle speed to 1500rpms to pass the idle check. The advance is usually affected by the idle speed.

In a CIS system with 30 year old rubber and an air-cooled engine, first look for vacuum/air leaks around the injector seals and distributor boot. These should be changed regularly because they harden like a rock, shrink, and crack.
These are available from our sponsor.

It might be possible the advance is o.k. to Porsche specs at 6,000rpm, but the distributor advance springs are worn, and not affecting the advance at idle.


Next time, drive hard for 1/2hr before the test to warm up the cat, and don't let the car sit for very long before the test.

Andy,

The idle speed is easy to adjust, you can do it with your fingers by turning the large brass bypass screw on the side of the throttle body. Just turn it a little clockwise when the engine is good and hot (+10 miles) and set it to 950 by your tach. The timing issue sounds like the tech didn't know what he was doing. The timing spec is 5 BTDC with the vacuum lines disconnected. Your car has vacuum retard at idle, bringing it back to TDC. He probably checked the timing with the vacuum lines connected and misread the sticker on the engine lid. If that is the case, do not advance the timing, your HC numbers will go up.

By the way, there is no EGR on your car.

Paul

Thanks gentleman.
It was a cold day here (most don't consider low 60's cold, but we So Calians are spoiled!) and although I drove around before the test, I went in at only ~180 degrees. I'm not sure if he disconnected the vacuum lines or not, but I figure this weekend I'll take her out for a good run, then check the idle and timing and adjust as necessary. Wayne's 101 projects is going to save me again!! I need to get a timing light, and "but honey, a Porsche mechanic will be twice as much" is always a good explanation!
For the vacuum leak, is there an easy way to check for that?

Andy