Peqoud

I have a '97 Cab. Daily driver. I got the check engine light a few miles back (now cleared and waiting to return). I run only Chevron gas and keep up on routine maintenance.

My question though is does the style of driving (and frequency) have anything to do with the SAI issue? I give the car an italian tune up by running her over 5k rpms very frequently. I don't do this just to do it though, i simply enjoy it up there. So is there an error in my logic that higher rpms will burn off more carbon and thereby reduce the likelihood of buildup on the SAI ports, or is this a carberator only thing? I can not speak for my car's previous owner(s)' driving habits and yes I know my theory is slightly discredited by the prescence of the CEL on my car! Am I full of sh#t?? Any thoughts on this much-belaboured point??

obchuck

I'd be very interested to know the answer to this as well. I guess since my first car was a V8 (early-mid nineties in Kansas City, gas was $0.89 a gallon! I pay over $3 now in Bay Area!) I still drive on very low revs w/a soft throttle foot. 993 has nice amount of torque to put around in low RPMs. So, is Peqoud doing the right thing in his driving style???...and therefore me the wrong???

FisterD

I do believe the Italian Tune up is a good thing. When I purchased my car it had the carbon buildup problem. A Porsche dealer ( not that they would know what they were talkng about) told me that the car was probably babied too much.
As far as driving on "very low revs w/a soft throttle foot"...I think this is a mistake. These engines are made to run hard at higher RPMs. Too low and you are lugging the motor, which is bad. I generally always run my car at 3k + on the tach, many times taking it over 5k before shifting. Hell, the motor doesn't even begin to sing until @ 4K! I think babying these motors is a big mistake.

obchuck

A question for the wrench I guess. I do "clean the pipes" when out on a high speed run now and then though, or short spurts.

ron_dargenio

My Porsche wrench told me the same thing: cars that get the CEL most often are the lightly-driven garage queens.

amfp

This has nothing to do with how the car is driven when speaking with 993 techs and owners. Yes it only happens to garage queens, hwy driven cars with lots of miles, and track cars, and to daily drivers. This is simply a system that needs service cleaning every 20k to 30k miles. But there seems no specific reason why some 96 to 98 get CEL, and others don't. My 2 cents.

Novice

My advice is don't jump into conclusion so quickly without pulling the DTCs code first.

luv2ride

I would have to agree. I dont let the RPM's drop below 2.3 and I only use 6th gear when driving over 75 mph. My $.02

amfp

Agree. Playing Russian roulette without pulling and clearing codes to determine what you are up against.

InTheAir

There are a couple of things to note/address in this thread, so sorry if this seems somewhat rambling.

The first question - what is an "Italian Tuneup"?
Generally, as it is used around these here parts, an Italian Tuneup consists of warming up the engine to normal operating temperature (at or above the 8 o'clock--you'll see the temperature crest the 8 o'clock position and then go down as the oil begins flowing to the cooler). Once at this normal operating temperature, the engine is then driven "agressively" for a "prolonged" duration of time, typically above 4000 RPM for 45 minutes to an hour (read: 4000RPM being the minimum, but trying to ~stay~ above 5000 RPM or so).

The technique is believed to heat the engine up and clear some deposits in the fuel system, combustion chamber, exhaust system, etc. and lubes seals, etc. (but will it clear a SAI? see below).

So, do Italian Tuneups really work?
Some swear by them as "maintenance", while others just say they are fun and don't do much. I think it is probably somewhere in between these extremes--I believe these engines like to be driven hard rather than babied. In fact, you rarely hear about problems with these engines when track driven, but do hear of problems if they are coddled. Thus, I tend to drive mine below 3000 RPM until warmed up and them maintain it above 3000-3500 RPM to just below redline.

Can an Italian Tuneup help a clogged SAI?
I have to disagree with the learned mechanic. I realize that is against the "code", but I've come to realize that mechanics don't necessarily have the absolute answer.

Technically (read: as designed), the SAI ports are open during the initial cold start to provide air to the exhaust port for emission control. The port is controlled by a valve that opens it only during this cold startup and for a short duration after startup. Eventually, the valve closes the ports and there is no/limited flow.

Unfortunately, in the real world, these valves get corroded and fail to completely close the ports. As a result of this failure, combustion products (soot, carbon, etc.) can make their way into the SAI port and collect, thereby clogging the port. Once clogged to a predetermined amount, the CEL is tripped.

As you can imagine the exhaust route like this: _____/_____, where the __ is the exhaust route and the / is the SAI port, you can see that there is not a lot of flow through the SAI port during normal driving. During an Italian Tuneup, this SAI port (/) still gets little to no flow. Therefore, it is unlikely to be "cleaned" out during the process.

Therefore, I see benefits to the Italian Tuneup or at least to driving the car agressively (helps remove deposits, condition seals, etc.). However, I don't see how the Italian Tuneup can help a clogged SAI port.

I hope this helps.

Full Disclosure: I am not a certified Porsche Technician. However, I did stay at a Holiday Inn Express last night.

Marv

Read the codes first!

jimbo3

There are many reasons to get a CEL and the carbon that your mechanic is refering to is likely to be just the build up in the combustion area, which has nothing to do with SAI. My mechanic mentioned that same issue and also recommended upshifting at 4000 rpm or greater. He's "fixed" a few by running the snot out of them for 20 minutes.

What Jeff wrote is spot-on.

Bottom line- Change out your SAI valve every 15,000 miles!!

Peqoud

I pulled the code right after the CEL came on. I had a hunch it was the dreaded SAI problem and it was (code 1411 If I recall). I don't know how long the system takes to reboot itself after the reset but I have not had the light thrown since, although I am sure it will reappear. Thanks for all of the insight - I still don't have a definitive answer but I will continue driving north of 4k rpms as it is a joy!

Cheers

993RS

Italian tuneup at 5K revs? For me, an Italian tuneup is to redline it.

Bill P.

I agree with Phil. Preferably in a gear higher than 2nd (puts the engine under load).