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Greetings Saturn Enthusiasts!
Please enjoy the latest January SPS Updates…
A Review of Engine Management
The methods and logic through which the Saturn powertrain control module (PCM) makes decisions to keep the Saturn engine running smoothly and efficiently is a subject that is often misunderstood by performance enthusiasts. And while the complexity of the algorithmic equations that it uses is beyond the confines of the monthly newsletter, a brief review of the fundamentals here may prove helpful.
It is important to understand that the Saturn PCM only controls two primary functions of basic engine management – fuel delivery and spark timing. (So unlike a turbocharged car, one cannot simply increase power output by adjusting the computer’s factory-programmed boost levels.) Of these functions, the most misunderstood – and arguably most important – is fuel delivery.
The PCM’s processes – or decisions - that affect fuel delivery can be categorized in two distinct modes of operation: "closed loop" and "open loop." For the most part, closed loop operation occurs whenever the throttle position is less than wide-open (partial throttle application) and open loop occurs whenever the throttle is wide-open (full throttle application.)
During closed loop operation, the PCM considers input from various sensors and varies the amount of time that it opens the injectors (this time is known as the pulse width) in an active effort to maintain stoichiometric (14.7:1) air and fuel ratios. It begins by considering input from the manifold absolute pressure sensor (MAP) and the throttle position sensor (TPS.) As manifold pressure increases (vacuum decreases) and throttle position voltage increases, the PCM assumes that the throttle is opening further, thus allowing more air into the motor and requiring additional fuel. And conversely, as manifold pressure falls (vacuum increases) and throttle position voltage decreases, the PCM assumes that the throttle is closing, thus allowing less air into the motor and requiring less fuel.
But what "closes the loop" during closed loop operation is the function known as the "block learn feature." The block learn feature allows the PCM to analyze its effectiveness in maintaining stoichiometric ratios and to adjust its response to manifold pressure and throttle position on-the-fly for better accuracy. It does this by measuring the percent of oxygen within the exhaust gases (via the oxygen sensor) and considering these results when making on-going fuel delivery responses. So if the PCM consistently recognizes exhaust gas oxygen content that indicates rich or lean conditions, then it will modify its response to each and every set of MAP and TPS inputs until the rich or lean condition no longer consistently exists. Hence, the PCM "closes the loop" by making a decision, executing the decision, evaluating the results, and considering the results within the framework of its next decision.
However, the process changes once manifold pressure reaches atmospheric (a lack of vacuum) and the throttle position becomes wide open. Under these conditions, the PCM assumes that the operator has intentionally opened the throttle to a wide-open position or engaged "full throttle" operation. And it reacts to this by moving to open loop operation. Open loop operation is characterized by a sort of "tunnel vision" logic in which the value for injector pulse width is pre-established within the PCM. Once the PCM realizes that wide open throttle conditions are at hand, it more-or-less blindly resorts to the pre-programmed pulse width and sticks to it without looking back (so to speak.) During open loop operation, the "loop remains open" in the sense that the PCM ignores any feedback from the oxygen sensor and continues following the pre-established pulse width instructions until full throttle conditions no longer exist and it returns to closed loop operation.
To learn more about fuel delivery in the Saturn motor, please check out the May 1999 tech article entitled Fuel Delivery within a High Performance Saturn Engine.
Product News
Our new imported strut tower brace may not exude the quality craftsmanship of some others on the market, but at this low price, you may not care! This bolt-on brace strengthens the area between the front upper strut towers to increase chassis rigidity for better handling and improved steering response. And it features a highly polished cross bar with powdercoated black brackets. Fits all SOHC and 91-96 SC and SC2 Saturns. (Note: brackets will contact hood liners on some DOHC models.) The VIB1840 is in stock now and sells for only $49.00 each!
The black emblem kits have been one of our most popular items ever since their introduction. And they are now available for the 2000 models too. All 2000 Saturns with painted front fascias (everything except the SL) use our newest 3-piece kit – the EMB003BL for $29.00. (The 2000 Saturn SL with the unpainted fascia uses the EMB001BL.) All kits are in stock now!
Everybody knows that aftermarket manual shift knobs are easy to find – just check out our large Momo selection for instance. But enthusiasts with automatic transmissions have been requesting something different for quite some time. Now SPS is proud to offer a line of vertical automatic knobs with a top-mounted push button. These unique knobs are easy to install and come in a variety of finishes including polished silver, anodized red, anodized blue, gun-metal black, black leather, and carbon fiber. Pricing for most of these units is only $39.00 each ($49.00 for the carbon fiber.)
FET’s CATZ Galaxy White Bulbs have earned the reputation as the "hottest" bulb on the market. Thanks to a unique coating procedure, the Galaxy White bulbs create an extreme HID-look while maintaining excellent lighting efficiency. And – as with any FET CATZ product – they provide legendary quality with exceptional value. Our newest FET H4 Galaxy White bulbs work great with the HE4165 headlight conversion kit. The CZB-41 bulbs employ a 55-watt low beam and 60-watt high beam. They are available now for $69.90 per pair. (Sold in pairs. For off-road use only.)
Many more new products will be introduced very shortly. But although we are excited about the new items, we are trying very hard to use discretion about releasing new product information because sharing any information before solidifying all of the facts can inadvertently mislead customers, employees, and supporters. Please visit our web site often and watch for future updates. Many more exciting items are on the horizon!
January Specials
SPS braided stainless brake lines replace the stock rubber flexible lines and eliminate outward expansion during braking. The result is a firmer brake pedal, more confidence, and more control. All sets are DOT-approved and come complete with new OE bolts and washers. All non-coated and clear-coated line sets are on sale for December for only $125.00 per set – a 10% savings!
You want new rotors and pads, but you can’t spend a lot of money? This package may be the answer. Stillen cross-drilled rotors and Metal-Matrix pads offer better pedal feel and higher temperature thresholds. And together, they make a great value-oriented package! Get the Stillen cross-drilled rotors and Metal Matrix pad sets together for only $199.00! (You choose either front or rear – or get all four for only $398.00.)
Close-out Kayne exhaust piping is still on sale at blowout prices while supplies last!
Features include: 2.0-inch mandrel bent construction, integrated resonators, T-304 stainless steel material, a special flange at the catalytic converter that fits both SOHC and DOHC models, modified rear sections for easier installation, and included gaskets and clamps. Save $100! The T-304-grade systems are only $249.00 each! (Does not include muffler. Only "SS" short wheelbase systems are left!)
We also still have a few leftover items and returned items on hand that we would love to sell fast. These items include:
SCRT001 – scR motorports T-Shirts – now only $14.95 each – Save $5.00 each!!
Please visit the SPS web site (http://www.spswebpage.com) for more details!
SPS Racing
If you have not yet seen the new Thundersport Racing video, check it out on the SPS Racing page. Thundersport Video offers a glimpse into the excitement of the 1998 Valvoline Runoffs at the MidOhio Sports Car Course and includes lots of amazing in-car footage from Mike Kramer’s Thundersport Racing SC2.
In other news, scR motorsports star James Walker has begun the preparation necessary to rebuild the ill-fated motor in his ITA SC2. For now, most of the preparation has been on paper, but the physical work will begin soon and James plans to be racing at the start of the 2000 season in April.
Mark Rushbrook has still not committed to racing alongside James Walker in ITA for the 2000 season. But in December, SPS received an order from Mark for the 17.5mm rear sway bar. And since Mark is a relatively conservative OEM-suspension engineer, we find it unlikely that he would install a racing bar on his street-bound SC2. As more information becomes available about a metamorphosis to Mark’s SC2 or his commitment to race during the upcoming season, we will let you know.
For more information about scR motorsports, the rebuilding of the ITA motor, and the development of the 2000 season, please visit the scR motorsports website at http://www.teamscr.com or email Mark and James at
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SPS Contributes to Grassroots Motorsports Magazine
Most SPS customers are aware of the growing Tech Article Archives section of the SPS website. Since its inception, the tech section has provided a vast array of accurate technical information for free to anyone willing to take the time to read and digest it.
Recently, the July 1999 article on controlling body roll with anti-sway bars was reprinted by Grassroots Motorsports magazine on page 87 of their February 2000 issue.
To learn more about Grassroots Motorsports magazine, to review portions of the latest issue online, or to request a free sample of the magazine, visit them online at http://www.grassrootsmotorsports.com.
SPS Events
The SPS schedule for 2000 is starting to take shape. If you have suggestions for a 2000 event that you would like us to attend, please Contact Us.
SPS 2000 Schedule (tentative)
Mar 25: SPC lapping day at Putnam Park (visit http://www.saturnperformanceclub.com for more details.)
tba: the scR motorsports schedule (look for a May debut)
tba: the Thundersport Racing schedule
tba: the SCCA WOR solo2 schedule
tba: Pilgrimage 2000
If you have any questions about anything in this newsletter, please Contact Us.
To view previous editions of the newsletter, please visit the Newsletter Archive.
If you wish to add an email address to the list, please do so at http://spswebpage.com/email/addemail.com or if you need to remove an address from the list, please do so at http://spswebpage.com/email/del.html. Please do NOT notify us directly with your removal or addition requests!
Until next month, HAVE A GREAT NEW YEAR!
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