Car not passing smog

eurocarrera · 02-27-2002, 09:57 PM

Any ideas: It is a 1985 Carrera, and it passed fine last time. I figure if I change the oil, filter, cap, rotor, plugs, and air filter, it should probably run fine. The CO is a little high. The Air Flow meter was rebuilt when I bought the car, and it has a DME unit, so there is not much I can think of to do. Additonally, I just threw in some Swepco fuel improver, and some 108+ octane booster.

02-27-2002, 10:13 PM

At what point of the test did the car fail?
Idle or High speed?

makaio · 02-27-2002, 11:08 PM

We need to know what part didn't pass.

Also, make sure the motor is nice and warm.

Jorgeman · Jorgeman's Garage

I'd only add running a bottle of Techron or ProGuard thru it to clean up the spritzers and making sure you had the car thoroughly warmed up before going in for the test. Good Luck.

george 86T

eurocarrera · 02-28-2002, 08:24 AM

I will check the printout from the computer today, but I think it was not passing at the 2500 RPM mark. What about the valves? I just check my records, and it has been about 20,000 miles since I last adjusted them. I am getting ready for the Autocross sean, so I certainly don't mind doing the tune up stuff, I am just hoping it isn't something else.

Also, does anyone know how to ventilate the crankcase? When I originally purchased the car, I took it in for a pre-inspection out to a mechanic in Livermore who used to work as a Porsche Tuner in Germany. He said that it was quite common for the cars to not pass smog sometimes if the burnt gasses were still trapped in the crankcase. He somehow ventilated it - which he said was not very legal. No names mentioned.....

StuttgartDavid · 02-28-2002, 08:35 AM

Were the octane boost and fuel additive in the tank when you took the test? I believe you should run only good quality gas, nothing else for a smog test. A US SC or Carrera should pass a smog test with no problem - something else is wrong here.

eurocarrera · 02-28-2002, 08:44 AM

Oh, by the way, this is a Gray market car that got the EPA sticker when it was brought over. So, it has the higher compression. The catalytic converter went out with the previous owner, so he had it replaced with a known good one. The little "black box was added to the top of the DME unit for the EPA, and it is connected to the oxygen sensor, however, the unit was never activated - it is just there for looks (i.e. I really have no working oxygen sensor).

stlrj · 02-28-2002, 09:18 AM

You might try setting the mixture on your air flow meter which is also called a CO adjustment screw.

See of this helps:

http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=54799&highlight=mixture+adjustment

Joe

dickster · 02-28-2002, 11:32 AM

i've heard that the sensor should always be connected (?)

the engine will run rich without it??

which then damages the cat. if you've got one.......

or i am missing something???.................

Kurt B · 02-28-2002, 11:32 AM

My car passed at idle but failed at all higher RPMS very badly for CO. After putting a new cat on, it made no difference.

Turned out to be a bad air flow meter. Replaced with a new one, and it passed with flying colors.
s

eurocarrera · 03-01-2002, 08:20 AM

I checked the printout from the smog check last night, and it the car failed at 2500 RPM.

These were the results of the CO(%)
Max= 1.20
Ave= .20
Meas= 1.45

I think this is kind of strange, but it actually measured Zero at idle. Do you think this would be as simply as having someone adjust the mixture screw on the Air Flow Meter? As I mentioned before, when I bought the car, the mechanic I was using had the unit rebuilt. Thank you for any advice.

03-01-2002, 10:17 PM

What are the numbers for:

Idle HC CO CO2 O2

High speed HC CO CO2 O2

john walker's workshop · 03-02-2002, 07:50 AM

lack of the oxygen sensor is the most likely culprit. if all else fails, unplug one injector and go thru on 5 cylinders. that cylinder now acts as an airpump and the emissions will be noticeably reduced. on engines with a low compression cylinder, which can cause high HC, unplug that injector. on CIS cars, braze up the tip of an extra injector. on carb cars, plug a mainjet with a round toothpick and break it off. you didn't read this.

03-02-2002, 10:27 AM

Take it to a reputable shop with a 4/5-gas tester and have them diagnose and repair the problem.
Much easier than throwing parts at it that may not correct the problem.
This is one area that not having the correct equipment can cost you lots of money in parts and time. So this is about a skill level 10 for a DIY project unless you have a 4/5-gas tester.

Chris

eurocarrera · 03-03-2002, 07:29 AM

Thank you for the input everyone, but I was able to get it to pass. By the way I usually do a tune up annually anyway regardless of the fact I only drive about 5k per year. Here is what I did to correct the problem:
* Backed out the screw on the air flow meter a half of a turn (I called my German mechanic, and he said it would lower the CO a 1/4 to a 1/2 of a point - which it did) to lean out the mixture. The plugs had a bit of oily carbon build up on them anyway, so this was a good thing

* Changed the rotor and disributor cab
* changed the air filter
* ventilated the crankcase: Behind the airbox on the 84-89 models is a hose that connects to the crankcase and the oil resivoir tank to keep the system closed looped. This is also connected to the air intake system. I simply disconnected the hose and let the vapors out.

Final test results at 2,500 RPM, was 1.04 (1.20 is not passing).

Bottom line, I will eventually take it in to have it correctly adjusted, but now it runs GREAT! Smooth acceleration, and much faster than before.

In regards to the comment about the oxygen sensor: It was never hooked up to begin with, and is not connected to the DME - there is no input for it since it is a gray market car. I can only assume that if it were an american car that the oxygen sensor would tell the DME that it were running too rich, and make the appropriate adjustments electronically? Once again, thank you for all of the suggestions.

82SC · 08:14 AM

HAHAHAHAHA I love JW's idea!!!! that is hilarious...

could I run carbs on a SC car upped to 3.4L; with 2x plug; high CR; S-cams....plug up injectors to pass the test??? maybe turn my car into a 4 cyl car for the quick trek down to the smog check place

that would be SO cool for CA cars?
do they check in the engine compartment at smog places or just under the engine...

hahaha...that was a nice morning laugh...

I am laughing but I am half serious....if so I would love to ditch my CIS and get my carbs now....

StuttgartDavid · 03-04-2002, 09:41 AM

82SC: I also have an 82SC and love it. We all would like more power, but remember that Bosch wasn't joking when they said:

"Research has consistently proven that fuel injection makes significantly more power than carburators on a comparable engine design, with better fuel economy and emissions."

Though not as modern as new digital systems, a CIS 3.0 engine is a finely matched package that extracts most all of the power that is theoretically possible to get from that engine (whether running SSIs or not), consistent with OEM requirements for flexible street use.

The only reason to ditch the CIS for carbs is to be able to run a much more radical camshaft than CIS will tolerate. (Remember, while it ain't an 'S' cam, the SC camshaft is more aggressive in lift and duration than most people realize. Without a change to a really radical cam you may not notice much difference.) This will boost top end power, but at the expense of the mid-range powerband and driveability. Fine for a race car, lousy for street. Unfortunately, you need to replace the pistons to get the valve clearance for a more aggressive cam, so now we are out of "bolt on" and into "big bucks." Even if you swallow this, it doesn't make a great race car yet, unless the rest of the package -ports, compression, ignition, exhaust, bottom end, even gearing - is optimized to work with your changes. Otherwise, you can wind up with higher peak power in an unsmoggable motor, yet it will still be slower than a stock smog motor, even on the track, because it has less total useable area under the curve!

Bottom line, unless you completely rebuild and re-engineer your engine for a differently application, leave the CIS on an SC. Porsche already gave us one of the best dual-purpose street/race engines ever built with 3.0L. You can't improve on it without big compromises and big bucks. If you must have more power for a street car in CA , keep the CIS and go to SSIs (which are really just Porsche's pre-74 factory exhaust), and reinstall your old exhaust every 2 years. Do anything more, and you will wish you had just put in a 3.6 instead.

82SC · 03-04-2002, 10:48 AM

good advice...

well I have decided this

SC
add 3.2L crank
3.2L con rods
98mm deep pocket 10.3:1 CR Mahle P/C's
964 cams
3.2L heads ported
twin plug
964 cams...
SSI

I have half the parts on this list already...massive shopping around and I found some great deals...
I wanted to go to CIS for induction but Ihave decided that if I can find a cheap pair of carbs I will do the switch, and just switch back to CIS around test time...but If I can't find them cheap I will wait till 2007...get my historical plates...slap on carbs and S-cams (see how I planned ahead with the deep pocket pistons???)

And leave it at that...now if I can just find a cheap euro SC intake....then I can kinda get some induction increase and still be able to tune it to pass smog...hmmmm

john70t · 03-04-2002, 11:17 PM

You might want to shop around for a smog station that will do a "pre-test" under operation training mode before your time come up. That way your VIN won't show up at the DMV as a gross polluter untill you get a chance to make some corrections.

If you disconnect a few injectors you may run the risk of having the machine recognize sample dillution (i.e. too much air from an exhaust leak) and abort the test. I think CO2 and CO have to add up to 14 percent. High CO could come from from leaking injectors, high fuel pressure, air/ect temp sensors, lack of O2 sensor(reverts to limp/open loop mode I think) or a bad cat. See if you can get a sample before the cat and after to see whats changing. Keep the engine super hot and make sure the mech opens and closes the trottle slowly. Good luck.