914 smog problem #2

[john911sc]

okay...sorry for the last information....let me try this again.....i have a 1974 914 2.0....it did not pass smog....30k on new rebuilt....i looked at the readings on the computer screen at the smog station.....i think they said....483 on the left side and 367 on the right side....the guy said it should be at 100 on both sides....i'm not a smog pro or a mechanic......but i have restored it this far...i would like to be able to adjust it to pass....anything will help....thank you to everyone who has helped....thanks again..john...

[bowlsby]

You need access to an exhaust gas analyzer, to check the emmissions levels, usually at a mechanic unless you have that equipment.

Assuming the engine is in a good state of tune, there is not much to adjust really. Be sure that it has a recent tune-up, valves, timing, points, plugs, vacuum hoses, filters, etc...all to factory specs. Do not adjust the MPS.

The idle mixture can be adjusted with the ECU knob, then the idle air screw on the throttle body, but you need the EGA to determine emissions levels. Pretty much everything else is not adjustable from an emmissions standpoint.

You should have gotten a printout of the levels the smog tech read, which you can give to a mechanic. you may have faulty sensors or othjer equipment if the system is way off.

[campbellcj]

The measurement that has 100 as the max (here in Calif) is HC - Hydrocarbons. It's 100ppm.

I am not really sure what you can do about that, assuming the car is not running extremely rich or burning oil.

I'd advise taking it to a Porsche/VW knowledgable shop who can at least do some diagnostics, and ideally also do the smog test for you. It might cost you $150 or so instead of $60, but at least it would be over and done with and you'd be good to go until next time...

[pbanders]

I'll say it again - save yourself a lot of time, trouble, and probably $$$ and go across the bridge to High Performance House. Rich has been working on 914's for probably 25+ years and can get your car to pass, if it is at all possible.

Comment to campbellcj: a leaner mixture will also reduce HC. Check the Bosch Emissions guide for the charts on page 10:

http://www.wrenchead.ca/pub/Bosch-Emissions.pdf

Note that if you go too lean, HC will rise again, but if you're significantly rich (lambda of 0.85 or so), you can significantly reduce HC by going leaner.

Note also that spark advance has a fairly strong effect on HC, but almost no effect on CO. Make sure your timing and dwell are set correctly, and that your plugs are properly gapped and the system is in good condition.

BTW, a limit of 100 HC at idle for a '74 2.0 is pretty damn hard to achieve, even with your engine in really good shape. Here in AZ, the limit is something like 250 ppm for that year.

Brad Anders

[rfoulds]

Those readings are extremely high for a stock 2.0. It is stock, isn't it? With all stock fuel injection in place?

In CA, most reputable smog inspection stations will do a "pre-smog" for you, which basically means making sure all th eparts are there, and sticking the sensor in the tailpipe and looking at the readings. This way, if it fails, it isn't reported to DMV and you have a chance to fix it before it is officially done.

I did a pre-smog on my 2.0 with carbs, and the readings were in the 400's. my 1.8 with stock FI passed easily, with some slight timing tweaking.

Find a better shop, and they will help you a lot more with getting it past. It sounds like the one Brad Anders is recommending should be your first stop.