Failed E-test in Canada #3

targa88 · 05-28-2005, 06:04 AM

First test results (coming out of six month storage):
Curb idle test passed with more than adequate margin.

ASM 2525 Test
HC ppm 48 (limit 66)
CO .46 (limit .37)
NO ppm 588 (limit 757)
RPM 1783

Second test after DEW (using 94 octane gas Sunoco)
HC ppm 42
CO .46
NO 946
RPM 2443

Third test after emptying tank of high octane gas and changing 02 sensor
HC ppm 50
CO .37
NO 840

Failed on the No, and CO is now borderline.
I really don't want to spend the money to change the cat. So are there any suggestions. The tech suggested doing the test cold?

Kurt B · 05-28-2005, 06:59 AM

You probably need a cat. When my car runs now after having been adjusted by TRE the CO is almost zero...in fact, on my last test, it might have been completely zero. As a result, the NO goes up due to extra heat.
A cat should take care of that for you if it's new.

You can try everything else to get the combustion temps lower, but I finally gave up. Adding lots of booster could do it too. Like 3 bottles to half a tank or something. It's sort of odd that your CO and NOX are both off. Usually they're proportional (maybe not directly, but at least indirectly). As the CO goes up due to running richer, the temps should drop and the NOX should go down. It's working these two on a see saw that caused me to give up.

johnsjmc · 05-28-2005, 07:03 AM

I am a class A tech in Ontario also and I think it looks more and more like a failed catalyst. The catalyst essentially works in 2 sections.The front section of the cat "strips"the oxygen from the NOx molecule and adds it to the CO andHC in the rear section to change CO to CO2 and changes the HC to H2O. When all 3 gases are high I suspect a catalyst failure. Your high Nox means less O2 to use in the rear to lower the others.There are aftermarket high flow cats that can be installed in the exhaust in place of the factory style. Any good muffler shop can probably do it for about $250 Cdn ( often plus premium if its a porsche but shouldn,t really be any harder)

targa88 · 05-28-2005, 07:53 AM

John,
Any specific suggestions or shops that you could recommend. I live in Ajax.

johnsjmc · 05-28-2005, 08:09 AM

I live in London but I would try Mufflerman or Midas down here. What about the place that did the etest. Have they given you a quote ?

targa88 · 05-28-2005, 08:23 AM

Reply,
No actually the place I went to did not have a ckue why the problem was persisting. So basically, what i am lloking for is a high flow cat?
I am just surprised that the car is stock with 72,000 miles and the cat would be finished?

johnsjmc · 05-28-2005, 08:52 AM

A single bad spark plug misfire can send enough unburned fuel into a cat to cause it to overheat and meltdown in a matter of 45 minutes. I have seen one on a 97 Jeep with 75000km that the core actually melted ,broke up and fell out in pieces.Another on a Windstar . I suspect yours is only partly failed and still working but not well enough.
I also could be wrong as my SC passed a few years ago with no cat. As the standards are tighter for an 88 compared to an 80 .The cat condition becomes more important

targa88 · 05-28-2005, 09:05 AM

Appreciate the heads up. NOw to find a shop that is willing to do Porsche. The local Mr Muffler was even willing to try....

johnsjmc · 05-28-2005, 09:46 AM

If it were my car I would use a sawzall and neatly cut out the cat and then mig weld in a replacement aftermarket one. The end result will look like the replacement picture I found on the performanceproducts website. Hope this helps. John