As reported earlier, car w 4600 miles, shows sooty left tailpipes with no excessive smoking. Called in this date by dealer for "Drivability Concern Evaluation" Results:" No PIWIS faults found. Plugs removed and compared, nothing abnormal. Compression test (in BAR): 20, 20, 20.5, 20, 20, 20.5 All good compression. Leakdown test results: 10%,11%, 9%, 10%, 10%, 9% All normal leakdown results. No faults found with running of engine". No explanation here for the tailpipe discrepancy but I will sleep better tonight. Any comments or findings on other cars would be appreciated. Gerry

 

Mine is due for the same on Monday - hoping for similar clean bill of health.
Will keep you posted.
Mark

 

Did they do both wet and dry compression tests?

 

This still does not axplain the extra soot. I would not stop here and find the real cause.

 

Agreed. Is the soot caused by oil blowby (apparently not in your case with solid compression numbers), or by fuel / mixture issues? It's hard to imagine that Motronic 14.x is not managing fuel delivery to the nth degree - otherwise, you'd have a fault code set.

Soot particle (nanosphere) formation is temperature dependent. Somebody mentioned the potential for a temp differential between the muffler banks/tailpipes and was roundly shot down a while ago; I think that that possibility should be revisited.

-don

 

I have compression #'s and leakdown figures as posted. IDK

 

Wouldn't know how to proceed.

 

Happy completion date. You are getting there!

 

Understood, gpjli2. I'm not sure that I'd know what to do next, either. I don't have the equipment to test this theory.

This should definitely be something that Porsche's tech team needs to research; I'm wondering how many reports of this issue have been recorded with PCNA...

-don

 

Thank you

 

I can tell you that on my car the left and right header/exhaust pipes are the same color and show no discoloration. This would suggest to me that neither bank is running significantly richer or hotter than the other. I have seen pix of motors showing one header/pipe blue and the other normal color. This you might expect with a major imbalance of mixture or a heat issue.

 

Soot is a product of running rich. Oil blow by will not produce soot. If the Motronic fuel map is programed this way it will not show a fault code. It is probably programed (rich) this way.

 

If it was from both sides I personally would be ok with the findings so far, but its only from one bank of cylinders...somethings not right. I'd start looking for answers from a very well known and respected independent Porsche shop, not to fix the problem but to have them give their written opinion why this is happening and what are the possible causes, I would then take this written diagnosis to the Porsche dealership and meet with the factory service rep. Remember the more people that report this directly to the factory rep, the quicker we'll all get some sort of resolution and/or explanation.

 

If what was from both sides? Ok with what findings? What respected indep. shop? You're losing me here 500.

 

Can't wait for results from your side of the pond. Should be interesting Gerry