Sold the 82..yea! Failed smog...****!

The guy is here in so Cal. He came with his mechanic yesterday to look at the car. Mechanic thought it was very nice, but would it pass smog. He told the guy to buy it if it passes, otherwise...

So today I put the old cat back on and thought it would pass with flying colors...not.

My question is:
I had changed out the throttle body and intakes to the Euro, put on MSDS headers and RRFPR. Would this make it run rich and fail? That is the only reason I can come up with. I don't have the original parts and have no interest in putting htem back on. I would just sell it out of state in ths case, but, does this seem fixable? Oh yeah, the O2 sensor is less than 2 years old.

Here are the numbers:

%CO2 %O2 HC (PPM) CO2 (%) NO (PPM)
TEST RPM MEAS MEAS MAX AVE MEAS MAX AVE MEAS MAX AVE MEAS
15mph 1727 13.8 0.8 128 45 174 0.93 0.16 0.82 1097 434 1113 FAIL
25mph 1688 13.7 0.7 101 33 184 0.73 0.14 0.95 927 357 1091 FAIL

Any ideas?

Thanks!

 

How about bagging the RRFPR or at least reducing the pressure to see if that clears the richness.

 

My money's on the rrfpr too Keith. I've seen fpr's cause simliar failures in the past. At least it's an easy fix.

 

Is your smog pump operational?

 

Everything is operational..No I just need to get hold of a good old fashioned pressure regulator. Anyone have one I can borrow?

 

Keith--

The CO measurement is the indicator of how your mixture is adjusted, and it's the one thing you passed. Don't mess with the regulator.

Meanwhile, the two things you failed, HC and NOx, can often be cured with new COPPER plugs. The HC measures the amount of unburned fuel that passes through the engine, a sign of poor ignition sometimes. The NOx is caused by high combustion temps, and the copper plugs seem to help that some compared to the platinums we love to spend on.

You'll also want to verify that you have the ignition timing set correctly. A little advance helps with power but can cause the HC and NOx to go high, especially at the relatively low test RPM's.

There are other possible causes, like some mechanical compression/leakdown issues. But your car seems to run plenty strong so maybe we can put those possibilities lower on the list.


If your tools are already on the way to Oregon, stop by tomorrow ((or tonight) and we can take care of any or all of these possible issues. Call me if you need help. I can find a plug wrench, torque wrench, never-seeze and a timing light.

 

Dr. Bob. I misread the CO readings. Good advice.

 

Dr. Bob, excellent diagnosis, and very generous offer

 

Yes do everything like Dr Bob suggested and throw some of this into the gas tank:
soltron fuel treatment

We use this stuff on our diesel gensets and it really does make a difference.

 

Any chance the car wasn't warm enough? My Blazer needs to be good and hot for the cats to work right for smog purposes.

 

I have had success w/the Fuel additives when I resided in CA. Worth a try. Here in S. UT no smog requirements......Peace at last from the CA Bureaucrats!!

 

Bob was generous with his time this morning to go through the possibilities with. There really wasn't a whole lot that we did. Timing was 3 degrees out, reduced the fuel pressue a few pounds to just above lean. Replaced plugs and 02 sensor...both may or may not have needed replacement, but we did it anyway. Thats pretty much it. I went for a retest, and passed the 15mph, but failed the 25mph. Only thing left was to buy a brand new cat. Got that done and she passed with flying colors.

Sold the car and waved good-bye to it at 6:30PM..

Thanks for the help out there!

 

congrats Keith, and Bon Voyage!

 

We spent some time going over the test sheets that Keith had from the tests. First sheet was a no-cat test, second with the old cat installed. The differences in the readings were small, and consistent with the change in backpressure caused by the cats. It looks like the headers were scavenging too well even at low speeds, and some intake charge was moving through to the exhaust while both valves are open, at TDC on the exhaust stroke. So the battle was to reduce the mixture to where it would pass HC and CO at the same time. But we were getting beaten up on NOx from the leaned-out mixture, even after correcting the timing back to spec.

So we looked again at the test numbers, and decided that the fall-back was a new cat. The old one obviously wasn't doing anything except adding back pressure. Keith supported this with some info from the installer who welded the old one in for him: Substrate is discolored dark, and it looked marginal. Installer was right, and the early test results supported that.

We discussed leaving the car in first gear for the 25mph rolling test. The test guy said that the machine wouldn't accept the higher RPM's and would void the results. I guess the guys who build the software have been there before. Doing the test in first would give a little better dynamic compression, and the better cylinder cooling might help with the NOx reading. But Keith didn't get to test that way.

The new cat took care of the problem for sure. The new owner has the benefit of the new cat, plus fresh plugs, a new oxy sensor, timing dialed in to spec, and maybe some slightly better fuel consumption numbers with the FPR dialed back slightly. The cat may help a little with the low-end grunt, but may also affect top-end power at the same time. A lot depends on how well matched the header design is to the pipes behind them.

Anyway, the car will be here in the area for the new owner, and perhaps another enthusiast is hatched.
-----

Keith has been one of the most enthusiastic 928 guys I've ever met. Along with Dan Bise and Tommy Estridge, and the support of the crew at 928 International, Sharktoberfest was born, grown, and continues today. It would not have happened without all of these folks, of course. Throughout the time I've known him, Keith has been more than willing to step up and help when something needs to get done. He manned the wrenches (and the drill) when a record seven wapter pump bolts gave up at a recent Timing Belt Party, working over 16 hours on someone elses' car. He has done this for other folks before, including such fun projects as motor mounts too.

PACNW is gaining a real treasure as Keith and Jen migrate north to Portland. SOCAL will miss you, Keith!

 

Thanks Dr. Bob
This exactally where I'm at right now, so I will be doing all of the above.
Being in the LA area, Where did you source the cat? I need it for my 83.