The MidShip Report©: 

BONUS Material

[by john miller; John-M1 @ ML1media.com]

I brought home a little something extra---a little 'bonus' material from Porsche Parade 2008–Charlotte….something that most other Parade go-ers didn’t. And I don’t mean a Rally Trophy (see Firsthand Report-Parade 2008 coverage on the ML1 Media Home Page)…which I didn’t technically bring home ---I gave it to my Rally driver, Lee Lichtenstein, for safe passage back to Chicago. No, what I brought wasn’t visible, and while not valuable, it was ‘expensive’. It was sludge. Yes, sludge. I have to repeat it, because those of you that know me are certain to assume I typo-ed that and meant FUDGE…which would have been a thousand times preferable. It was S-L-U-D-G-E. Post-Parade, somewhere between driving the Tail of the Dragon with two other PCA-ers and before Niagara Falls (look for coverage of this entire adventure in next months MidShip Report), the idle on the Boxster took on a decidedly demonic attitude. One minute it was steady, the next, it was bouncing up and down like a stock market index. Sometimes it was only 50-100 RPMs –almost unnoticeable. Other instances saw 250+ RPM swings ---really hard to ignore. I was fortunate in that it hadn’t (yet) triggered a Check–Engine light, and elected to chance it until I returned home and could treat the problem.

The ‘hunting idle’ as it’s sometimes referred to, indicated two immediate possibilities: 1). A fouled or failing Mass Airflow Sensor (MAF)–photo 1. ‘Fouling’ can be cleaned with an electrical contact cleaner –relatively inexpensive and quick---I say 'relative', because you have to open the engine compartment and fish a security-type torx bit to the top of the MAF and unscrew it (two screws). A failed MAF will set you back approximately $250 in the auto parts supply (after)market, plus a good twenty minutes to remove and install. Not overly horrible or expensive, but also not the problem facing the MidShip Boxster. Possibility # 2). Sludge on the Throttle Body plate. The Throttle Body (photo 2) is a box in the air intake line that has a moving plate, much like an old-style carburetor choke plate, that regulates the idle. It’s not uncommon for it to accumulate a buildup of oil and dirt (sludge) on the plate and the other moving parts. And it’s not something that requires replacement, but it does require an occasional cleaning. And to clean it is to remove it. However, in order to remove the Throttle Body assembly (four allen bolts plus a metric hold-down nut), one must remove the air intake tube (photo 1), and other attached pieces. While not complex, it is an expensive investment in time.

The cleaning procedure for the Throttle Body is initially no different than cleaning the MAF. Spray the entire Throttle Body (both sides) liberally with contact cleaner and let it drain off. For stubborn sludge deposits, I sprayed some Carb/choke cleaner on a paper-towel and wiped the gunk off (something you should never do with a MAF). Let it thoroughly dry – shake it gently to dislodge any remaining liquid/deposits before replacing. Replacing the ‘accordion’ plastic air intake tub requires a bit of force in order to reconnect it to the Throttle body housing. Including engine cover removal and MAF cleaning (which is recommended as periodic maintenance), the entire procedure took me almost 3 ½ hours. Undoubtedly, a dealer service department could accomplish this in significantly less time…but at significant higher cost than the $3 investment in contact cleaner. Naturally, with the investment in time an effort, having a look at and cleaning or replacing the air filter (photos 3&4) should be an automatic decision. Detailed instructions for the procedures can be found on several of the Porsche related web sites (Porsche Pete’s or Renntech are good resources). And so the Boxster idle was returned to the smoothness of a Pfaff (a German sewing machine). And I celebrated the extraction of the sludge with the consumption of…..fudge .

Look for full coverage of the Tail of the Dragon drive here next month at WWW.MIDSHIP.ML1Media.com

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