ROG100

Hi John,
Seeing Cambridge makes me wish for home - no! no! its sunny and warm here in Texas.
So far - tried different cats, O2 sensor, checked the computer to see if they are original and have not been chipped.
My tech who checked the car over is on vacation this week so I cannot verify if he did a vacuum test - I hope he did - he was the one who said I definitely needed new cats.
So I cant ask if he put it on the hammer or not - he normally does.
I have a new MAF coming so you could have a customer for refurbing the old one if it proves to be the culprit.
I can fax you all the readings from the emissions test if that gives you any further info.
Best,
Roger

Greggles

ViribusUnits

Interesting.....
I was going in a different direction.
Do you know if there is a difference in the air output by the smog pump at higher rpms?

John Speake

OK Roger,
I didn't realise you are an ex pat. We are seeing a few signs of spring here now, the soil is warming up a bit this week, temps are around 12-15C.

You could have borrowed a MAF from my US agent, who usually has one in stock.

WallyP

One possibility is that the air pump is not putting enough air into the cats for them to function properly...

Kevin in Atlanta

That's why it is so important to verify vacuum is present or not present at the diverter valve. Your mechanic can use a mityvac to operate the diverter valve and watch the emissions.

ViribusUnits

On a dual bed catalyst, the air is suppost to be injected after the catalyist that is to reduce the NOx. This is because NOx has to be reduced, or inother words, O2 removed from the compound. To assist this, it helps if there is a minimal amount of O2 at that point. The best possible situation for the cat is if there is no O2.

However, to assist in the oxidation of the CO, and HCs, your suppost to have extra O2. No O2, no oxidation. The idea of the smog pump is to provide that O2. For maximum effect it should be injected AFTER the first bed in the catalyist, but before the second.

Therefor, assumeing your system is built correctly, the smog pump should have minimal effect on the NOx of the system. That said, the 1980 cars are not built this way. For the 1980 cars the O2 injected BEFORE the cats. This causes the a reduction in the effectiveness of the cats at reduceing O2, and sometimes you can pass the emissions testing by deactivation the sxmog pump. I don't have an 80, but I have tested other vehicals with a similer system, and they seem to behave as theory predicts.

The smog pump should be a fixed displacement pump. For a given rpm, it should deliver a given volume of air. Higher rpms, higher volume. I don't think it's possible that the smog pump will dillute the exauste to a sigificant degree. I don't belive it pumps that much air. It's just not that big.

ROG100

I PASSED THE TEST THIS MORNING - Open the champagne!!!

Here is what I did since the last fail.
Yesterday (Friday) filled up with Chevron and added two bottles of Techron.
Tested for vacuum leaks around the fuel injectors and where the inlet manifold meets the block.
Checked all the vacuum pipes I could find and no obvious problems.
No leaks
Thanks to Sterling and Jim Bailey for there advice on how to do it.

Fitted a new MAF.

Drove 90 miles and went to the testing station. Talked the tech into running the test in 2nd gear.

Passed straight away.

NOx came down from the 1400/1900 range to 300/500 range. The other readings remained practically the same.

My gut tells me it was the MAF. The techron only had about 100 miles of use.

Thanks to everone who offered support and great advice.
Best,
Roger

Steve J.

Woo-hoo! That was quite an ordeal. Congratulations!

Donald

Roger-
So, our trade is off?
Congrats!

ROG100

It is now 12 months since I had all my troubles with passing emissions.

Car went to day to the same shop for the same test (no testing criteria has changed).

My good friend Schocki had told me that you have to remove the vacuum hose that feeds the valve to the smog pump. I think he said that this was a noted requirement by Porsche, however I will let him jump in and take the glory.

My car passed with "FLYING COLORS". The results were a night and day difference.

The only other thing (apart from disconnecting the vacuum line) that has changed since the last test was my timing was reset about six weeks ago as the cam gears were worn. This had in effect advanced the timing a couple of degrees.

See the results and you will see the amazing difference to the NOX numbers which were the main fail reason before.

Thanks to John Speake and Schocki

John Speake

Great result Roger. I think the adjustment of the timing had a significant effect....

Regards

ErnestSw

Now let's see what happens to your gas mileage.
Three weeks to go!!

Schocki

Roger,
Only a German can understand the deep thoughts behind engineering from Stuttgart

I did not expect anything else!!! Did you use my plugs???

Roger, here is my suggestion for the ultimate test: Go to the place again and leave the vacuum hose to the air pump valve connected. I bet you could confirm last years bad results. Just some thoughts...

Where did you buy the car again (state), do you still have emission results from the PO???

JBCaynee

Hi, My Cayenne is failing emission test due to O2 and catalytic converter not ready. The dealer recommended to drive over 150 miles and I have drove enough to make it ready but, it is still not ready without any engine lights or mechanic is unable to get a trouble code. Any recommendations? There are 4 O2 sensors and I am wondering if I should replace 2 at a time to test it out again.

Mrmerlin

how many miles are on the truck?
are the O 2 sensors original?,
when was the oil changed last?
When was the last time the codes were cleared?
do you use Startron in the gas?
do you add Techron every 3 K miles?