Now My Car Is A Gross Polluter! What's Going On?

[jyl]

My car failed smog by a whisker, I replaced cap and rotor, on the retest the car failed by a mile. What the heck is going on?

Here's the details. 1989 Carrera, 158K miles, engine is stock, no engine issues that I know of, burning roughly 1 qt/1000 miles, smokes sometimes on startup for 30 sec but otherwise no visible smoking.

The car was not running right - hesitating at 2000 rpm and making an intermittent "popping" sound, well down on power. So two weeks ago, I adjusted valves, replaced plugs, and wires. Turns out wire #5 was bad (infinite resistance). Plug #1 was somewhat black, rest of the plugs looked okay AFAIK (brownish/whitish). I think I left one valve a bit loose and noisy, but overall valves were quieter and hesitation was gone, popping was much reduced but very faint, power was all back.

I took the car to smog, and failed. Here's the results of smog test #1: at 15 mph HC 149 (max allowed 121), CO 0.51 (max 0.76), NO 193 (max 807). At 25 mph HC 97 (max 96), CO 0.08 (max 0.65), NO 734 (max 746). So I failed on HC, just barely.

Went by my mechanic - not a Porsche mechanic, he does my other cars - and he tested the 02 sensor as OK (inserted a probe into the wire, measured voltage as he sprayed something into the intake). He said the car was misfiring a little , hence the faint and intermittent "popping", and recommended I replace the cap and rotor, get the car good and warm, and have another smog test.

So I replaced the cap and rotor with new. Now the "popping" is all but gone - occasionally I think I hear a very faint "pop" but most of the time I can't hear it at all. Car drives fine, plenty of power. No smoking.

Well, here's the results of smog test #2: at 15 mph HC 535, CO 0.02, NO 1260. At 25 mph HC 390, CO 0.01, NO 1579. I am now a "gross polluter". Crap.

What could have caused my emissions to skyrocket like this? What should I do?

Here are some other details, if they help. All the events described above took place within about 50 miles of driving. My oil is at the "max" mark on the dipstick (checked at idle, engine warm, parked in garage), so I thought maybe I'd overfilled and oil got in the air box, but I removed the air filter and it is dry in the air box. I pulled plug #1, it is dry but the center post (electrode?) was dark. I pulled plug #2, it is dry and the center post is still white as it was when new (these plugs have, like, 50 miles on them). I checked and all plug wire connectors are seated, at the plugs and at the cap. Wires are connected in the correct firing order, although I will go check this for the 3rd time.

I read the epic 171 post thread where different forum members were trying to track down problems with their cars, 86 Carrera Hesitation problem , and my impression is that the list of things that could cause driveability problems with the Carreras is lengthy indeed, from vacumn leaks to bad DME to bad DME ground to ignition system components to the cleanliness of one's underpants. I hope I don't have to thrash at this for 171 posts!

The thing is, I don't have a driveability problem (anymore). The car drives great. I have a sudden 4X jump in my HC and 8X jump in my NO emissions, and I am baffled about it. (And also delinquent in my registration, which is going to get expensive . . . )

Any suggestions? Among which might be (if things get this bad) any recommendations for an honest and non-rapacious independent Porsche mechanic in the East Bay of No Calif?

[Zeke]

Can't help you in the least, but I love the expression "non-rapacious!" How true about so many shops.

Good luck on this. I would be as baffled as you about the increase in emissions after installing new plugs, a cap and wires and not touching anything else.

[jyl]

I went and checked (third time!) that the plug wires are installed correctly - traced them to make sure they are connecting the right plugs to the right cap contacts, verified they are in the right firing order, made sure they were all pressed down to "click".

I pulled the rest of the plugs and they are gapped correctly, plugs #2-6 look like new with virgin white electrodes, plug #1's electrode is dark so maye someday I'll have an issue with cylinder #1, but I can't imagine that is causing my emissions to suddenly quadruple.

I listened to the car idle. It sounds normal. I haven't been around enough 911s to know the subtleties of engine sounds, and there may be a slight "chug" rhythm, but there isn't any "popping" or evident missing, and that noisy valve isn't remarkably loud.

Arrgh. In the words of Piglet during the Great Flood of the Hundred Acre Wood,

"And he wrote on one side of the paper:

HELP! PIGLET (ME)

and on the other side:

IT'S ME PIGLET, HELP HELP!

[patkeefe]

We used to build engines for people in Arizona, Pima County. They have smog rules there. We have these rules in the Garden State also, but not as bad as you guys have it in CA. Some of these were like, big block Chevys and Fords, and we usually built them pretty hot. They ran like hell, but always failed emissions.
Bring it to someone with the equipment to measure the pollutants, do whatever it takes to de-tune it such that it will pass, and then tune it back to whatever it likes to make power and run well.
The problem is unburned fuels going out the tailpipe. Try hotter spark plugs, retard the ignition, lean it out, whatever it takes to reduce the unburned stuff. Catalytic converters loose their ability to reduce pollutants after time.

And, good luck.
Pat

[jyl]

Thanks. I'm really trying to solve this myself, partly out of interest and partly because the thing that makes having a 911 practical for me is that I don't take it to the mechanic except as a last resort.

Right after I got the car, the brake lights went out. I took it to a mechanic in S.F.. Paid something like $400 for what I later learned was to replace a switch at the master cylinder. That got me determined to DIY as much as possible.

My poor, non-DIY, neighbor got a used Boxster. His coolant overflow tank split when he was up in Tahoe. $900 for a replacement - you read that right. Now his mechanic - the local Porsche dealer - is telling him he needs his "cam cover gaskets" replaced for $1,200.

Anyway, I digress. Back to the topic. Heeeeelp!

[rrpjr]

Call Sam Sipkins in Oakland. A venerable old Porsche guy with his own shop. I'm sure he can set you right.

[yelcab1]

o2 sensor. at 160K miles, it is time.

[jyl]

Thanks, rrpjr - that's a good reference to a mechanic with a neat name, I could only like it better if he were named "Sam Spade".

P.S. I Googled him, he seems to get mentioned in 356 circles. Does he do the new-fangled 911s as well?

[jyl]

Originally posted by yelcab1
o2 sensor. at 160K miles, it is time.

I found this article on testing 02 sensors, both in and out of the car. http://www.gomog.com/allmorgan/o2.htm

The in-car test appears to be what my mechanic did (I was watching the voltmeter at the time and noting the values). So I think the 02 sensor is good, although I can't prove it didn't fail between smog test #1 and smog test #2. But perhaps I will take it out of the car and do the "out of car" test. It simply unscrews from the catalytic converter, right?

[rrpjr]

John:

Yes, He's 911 savvy. His first love is 356s but there's always 911s around the place. Last time I was in there he'd just rebuilt one. He serviced my brother's 84 and did the PPI on mine. In any case, he's old-school honest, and if he can't help or doesn't want to, will tell you. He's a character.

[Hugh R]

Sorry I can't help on the smog test, but yes, the o2 sensor screws out, watch the wires, or trace them to under the hood and unplug it first. Good luck. If you need a test cat. I have a spare (good (passed smog recently, but used) and will loan it to you for the cost of UPS both ways.

[jyl]

Thanks, Hugh - I'll be in touch if it comes to that.

Maybe this will be my excuse to get a sport cat. The GHL-made ones seem to be the same price as the DEC-made regular cats, at PP.

Damn - this is delaying my brake work.

[drive-ability]

The numbers say the car is running lean. A lean mixture will cause the HC to rise along with the NO and the CO will be low. There is a careful mix of lean to rich ratio needed to reach the best emissions produced by the engine. After that the converter trims any variation. I don't know much about Porsche engines but I do know computer fuel injection and emissions. If no fuel adjustments were made or air flow meter adjustments, I would replace your 02 sensor, testing one in a general way is simple. Connect a volt meter to the output side keeping it connect to the engine computer using a parallel circuit. The sensor should read above .8 at full throttle and in-between .1 and .9 driving. Set the scale low on the meter under 2 volts for sure. One way to check the low readings is to look at the meter when decelerating. Normally you will see the lowest readings. If the sensor is skewed they normally fail to produce the higher voltages .6 to .9 and thus cause the system to run rich. Thats not your problem so its likely not an 02 problem but should be tested. IF you see a reading thats high like .8 and above all the time that would make your system run lean surely at the areas where tested. I have not seen this much but does happen. Other wise I would say look for a reason the system is running lean. Low fuel pressure, fuel filter, basic system CO setting. Having said that you did say power was up but the emission test is done under light throttle and low rpm so I would concentrate right at that speed and rpm in looking for the trouble. Good luck and you may need a Porsche or good tune up fuel injection guy to iron out the problem.

[cisco06430]

my fav shop in the bay area is S-Car-Go in San Rafael... not saying they are cheap but I am sure they can 'fix' ya right up with the emissions

[rich22]

What about the mobile mechanic mentioned in a few threads? You could call and ask if he's got emissions-measuring equipment.

[jyl]

Okay, I will check the 02 sensor. Could a bad 02 sensor cause my HC and NO to be so high (3-4X max allowed levels)?

[yelcab1]

A bad O2 sensor can be outright bad, or just slow. And, either way, it would make your car fail. If you have the 1 wire sensor, it is pretty cheap, get it from Kragen or something like that and swap it out. Factory sensors are Bosch, and overpriced.

[drive-ability]

As for the use of an 02 sensor I would go with a generic, I will say again the normal failure of an 02 sensor is much like a battery it fails to produce higher voltages. Thus this would cause a rich condition not lean. I have seen many cars since I did smogs for 20 years test way off once and the next time on the other side of the scale. Ether test the good or bad may not show up again. Engines and test equipment can be subject to this from time to time. The low cost of an 02 ether way I would replace it. The sensor was in the exhaust flow of an engine which was running poor and could have been skewed. I set up my race ported Rx7 twin turbo with a volt meter while driving right at the test speed and rpm and before I did this it was a pig. After it was so clean it didn't need to go through the complete smog cycle. Thats rare for a old car. I couldn't drive it that way but it did get me my registration. Good luck

[studeb]

Originally posted by jyl
My car failed smog by a whisker, I replaced cap and rotor, on the retest the car failed by a mile. What the heck is going on?

Here's the details. 1989 Carrera, 158K miles, engine is stock, no engine issues that I know of, burning roughly 1 qt/1000 miles, smokes sometimes on startup for 30 sec but otherwise no visible smoking.

I took the car to smog, and failed. Here's the results of smog test #1: at 15 mph HC 149 (max allowed 121), CO 0.51 (max 0.76), NO 193 (max 807). At 25 mph HC 97 (max 96), CO 0.08 (max 0.65), NO 734 (max 746). So I failed on HC, just barely.

Well, here's the results of smog test #2: at 15 mph HC 535, CO 0.02, NO 1260. At 25 mph HC 390, CO 0.01, NO 1579. I am now a "gross polluter". Crap.

What were the CO2 readings on both tests?
Did the O2 go up on the second test?
i think the cat may not have been warm enough on the second test.
Changing oil before you test is also a good idea.

[jyl]

Originally posted by studeb
What were the CO2 readings on both tests?
Did the O2 go up on the second test?
i think the cat may not have been warm enough on the second test.
Changing oil before you test is also a good idea.

The report the smog center gave me doesn't list CO2. My mechanic's analyzer (the big red SUN machine) had a CO2 readout but I didn't note the reading.

The car was warmed up on both tests (above the first white mark on the oil temp gauge). Before the second test, I drove it around at high revs and got the needle to about 1-2 needle widths above that mark, which I think means around 200F. That's about as hot as the car usually ever runs - I've only seen higher on really hot days or really hard driving.

I changed the oil 2 weeks ago (hence my concern about possible overfilling, but the airbox is dry).