Repair-It

Fast_Ed wrote:This is an interesting but unrelated article about SAAB's "Knock Sensing" approach:

http://www.eeuroparts.com/blog/articles ... n-sensing/

Amusingly, the Saturn uses the 'checking resistances of the spark plug' approach to eliminate the need for a cam sensor as well. But it's far simpler, using the difference in resistance to tell whether it was the 'wasted spark' or 'ignition' event for one cylinder (#4 I think?). This complicates diagnosis of the 'Cam position sensor' code for that car.

Sent: Wednesday, June 08, 2005 3:00 PM
Subject: 9^3 Viggen


Finally got to drive it. He put some new tires on it, some summer yokos. Maybe AVS but I can't remember. He also installed a beefier rear anti-roll bar.

So here are my impressions:
First thing I noticed was soft seats. Not a bad thing, just something I noticed. Almost sits like an american car. Not sure on the support...I guess average for the level of performance the car provides. I may prefer the Camaro's seats, but I'd have to sit back to back to know for sure. They're worlds better than what the Caprice has. But what isn't.

Key in the console, funky way of shifting to reverse. But we all know that. Can't get out without the shifter being in reverse, either. Of course, it's been that way since forever, and now the C6 is like this, too.

Next thing I noticed was the really low clutch take up. The weight of the clutch is pretty good (heavier than my mom's car I think, which is good, but much ligher than the Camaro, which I'd expect), but the takeup is just so low. Kinda nice. Certainly not typical. Actually I think Jamie's sister's 2000 Jetta 2.slow 5-speed had a similar clutch feel. And the throw was also pleasantly short, I think as short as the Camaro. The gas was interesting, too. It has electronic throttle control so it doesn't feel natural in the slightest, but given the displacement and level of boost, I wouldn't want natural response anyway. There is a dead spot in the gas that doesn't seem to do much. Vaguely reminiscent of that TDI jetta I drove, but not as bad. This contrasts heavily to my mom's car, which has hyperactive throttle/engine response. This car has a more European throttle response, like an E30 with the M20 engine. I suppose that shouldn't surprise anyone. Combined with the low clutch takeup, it makes for potentially rough or lugging starts, but since I was aware of it, I compensated adequately. I think in terms of the just-get-in-it-and-drive ability, it scores higher than my mom's Maxima, but only because you'd err on the side of stalling the engine (preferred), as opposed to slipping the clutch at 4000rpm in the Maxima.

As you get into the throttle, nothing much seems to happen, so the engine feels relatively dead until you really prod it. If you push it like 3/4 way down, the spring tension increases and a few moments later, the boost builds and you feel that turbo sensation of torque. This is the first turbo car I've driven. It builds pretty impressive torque from low rpms, even below 2000. Only problem is, you have to wait for your 258lb-ft (in 3rd gear and up). That part I didn't like. The car basically has no ability to snap. It can quasi-snap, but it's still lagged and smoothed. The engine feels relatively effortless and smooth once spinning, which is good. It will happily churn along at 3500rpm at 40mph without feeling stressed or in need of an upshift. Is this related to the global GM Ecotec 4? The NVH I would consider to be above average for a 4 cylinder, especially given the specific output. The exhaust note from outside the car is also kind of aggressive for an OEM. From inside, you really don't hear exhaust though.

The shifter has very smooth action, with good synchronization, however, the motion is rubbery, long and imprecise, compared to the direct, mechanical, notchy feel of the Camaro's T56. It's like my mom's car except smoother (probably because of sheer fewer miles). Reminds me of an E30 BMW again. The car also doesn't like to be shifted fast, unlike an E30 BMW. Everything about the way it behaves prevents a good, hard, redline shift (the kind hondas just beg for). First, the engine controls keep rpms high artificially after you press the clutch, which was really irritating for me. Perhaps a concession for the turbo (to keep more exhaust flowing while you're off the gas). I've heard of N/A cars doing this, however. The shifter, while posessing smooth action, has the long and rubbery throws like I mentioned and just doesn't feel like it wants you to be slamming it from gear to gear. Finally, after you have engaged the gear and go to dump the clutch and floor the gas in the next gear, there's a strange whoosh from the engine, a delay, a jerk, then finally it starts accelerating again. Almost as if the PCM is saying "in Sveden, vee don't drive like zat." (They talk like Germans, apparently). All things combined, it requires even slower shifts than my mom's maxima (at redline), which is kind of a problem for what the car is marketed as. Hey, at least it'll go into 1st gear while moving. My mom's maxima is balky at best for 2-1s. Though there is no real point of going to first, seeing as how torque is so limited and the gear is so short. I bet timed acceleration is much better leaving the gear in 2nd, from as slow as maybe 10 or 15mph. Of course, this easy synchronization is probably how the car suffered the fate of a 1st gear downshift at 70mph...

It felt like it would be even with my mom's Maxima until a good way into 3rd gear. Actually I think it might fall behind until 50 or so. Then sometime around 75 or so in 3rd (where the PCM allows all 258lb-ft), I think it would catch up and maybe begin to walk away to post a 1/4 mile of a similar ET but a faster mph. This is all SOTP and it's been a while since my SOTP was re-calibrated...or since I've driven the Maxima.

And the brakes. I think I liked the brakes the most. There is a small dead spot upon initial press of the pedal (which mimics that of the throttle), but once you get through that, the brakes bite reassuringly but without being overly eager. Then, the modulation is extremely progressive. It builds stopping power smoothly, while also building the level of effort. It also doesn't require much pedal depression to go from medium braking to full ABS but since the effort builds, that is no problem. It sort of reminds me of the Z06's brake feel. Strong brakes. And the one time I hit the ABS (at least I think I did), it felt unobtrusive and transparent.

Steering was precise and a little too light for my tastes (similar to the Maxima). The biggest problem was the torque steer. I found the torque steer to be the worst in 2nd gear, probably because of the combination of speed and torque (in 1st, you are going slow enough that you catch the torque steer before the car changes lanes plus it limits the torque even more in 1st, but at 45mph, it happens faster). It actually caused me to cross the double yellow line at one point while accelerating. With a heavier steering effort, I think some of that could be mitigated.

Unfortunately, I did not get a chance to test the handling at all. Ed says the improvement between the tires and sway bar is very positive. The ride is smooth, well damped, so if the limits are as high as he implies, then it has a pretty favorable ride/handling combination. And with an EPA rating of 20/31, it's relatively efficient. On the other hand, the GM 3800 Series-II S/C provides almost that mileage with even more torque, snappy as hell throttle response, and similar acceleration. Too bad they're attached to mediocre W-bodies with 4T65-E trannies.

Overall impressions: good torque, once you wait for it, strong brakes. But I don't forsee buying anything with FWD, this much torque steer, and the turbo-type engine response. And that's just how Saab aficionados like it, that I stay away, leaving more cars for them.

Sent: Wednesday, June 08, 2005 3:48 PM
Subject: RE: 9^3 Viggen

There is little on this that I can argue. I really like the way the car corners now, but from people who have driven real performance RWD cars, the Viggen, even with the rear ARB, is nowhere close. The tires are Yoko AVS-E100's. front and rear ARB's are now 22mm. Before mod, the rear was 16mm.

All the 'quirkyness' is reversed for me when I get into someone else's car, as this is the 5th SAAB I've owned in a row. So I get into cars and reach between the seats to turn them on, cannot ever find reverse, and put my friend's SVT in cruise when I try to adjust teh stereo. None of the SAABs liked to be shifted fast or floored in first gear. The clutch takeup was always very high, however, unlike this car. I almost stalled it backing out of the dealership...

The seats are power adjustable, though the lumbar support is manual. I have that cranked up pretty high, pushing some people out of the seat a bit, but not my crooked spine. They hold you pretty well compared to other cars I've driven, though that E36 M3 definately had the potential to hold better had they been adjusted for me. The TT and SVT have nothing on my seats.

The engine is somehow related to the GM ecotec, but I think that's because that GM engine is based on it, not the other way around. It is very similar in design to the old SAAB 900 engines (I believe the heads are even interchangeable, but the blocks are not because of the different transmission layouts.. the 2.3 needs more room at the bottom end because stroke is longer than the 2.0's) Knock sensing is pretty cool: the spark plugs are heavily energized just after the spark event, testing the resistance of the combustion, and thereby somehow determining if knock is occuring.

Driving a car with a turbo does require a bit of attention being paid to boost levels, though it's probably more related to keeping the car at the right RPM and throttle position to ensure you're accelerating as much as possible. High RPM's are not as necessary, and, in fact, given the choice between downshifting to a gear where you're at 5krpm vs. just flooring it an waiting, I bet that you'd do better flooring it.

I've heard an old school car guy talking about bleed valves for power steering. I dont know much about them, but it sounds like something that could be used to bleed off a bit of pressure and lower the power assist a bit. If it would help with torque steer and it's safe/cheap to do, I'd definately like to try that.

SO, when you mention the E30 BMW with the M20 engine, are you talking about the E30 M3 with the 4 cylinder engine? I hear those are a BLAST to drive.

And I agree with that last line, more SAABS for me, because I am a creature of habit. I'm a little disappointed that I can't leave the Maxima behind till 75 though.. I thought it'd be earlier than that based on what I've heard from people who own them and have ridden in my car. But haven't gotten my hands on one yet...

Thanks for the write-up!

Sent: Wednesday, June 08, 2005 16:28
Subject: RE: 9^3 Viggen

On the handling, I'll just have to sample it on some real roads. I'm sure that'll happen someday.

Agreed on the quirkyness. Though not sure what ergonomic mishap causes the cruise to engage on the contour when you're reaching for the stereo. As far as ergonomic mishaps, both of my cars have the GM unistalk on the left of the steering column. Turn signal, high beams, cruise and wipers baby! To be honest, while most reviews tend to malign this setup, I find it very easy to use with everything in one place. So there you go.

To be honest, I should have paid closer attention to the seats. The only thing I really noticed was how soft the seat bottom was when I sat in the car. THe car itself is narrow enough that the seat back doesn't even need a ton of bolstering to keep you upright. As opposed to the Caprice where you need to use your arms and left knee to keep yourself righted. Since I am used to this, I tend to unfairly devalue well-bolstered seats, since I'm used to alternate means of maintaining posture. I will say that the 04 Pontiac GTO I test drove had possibly the most comfortable seats I have ever sat in. And I'm not the first to say that.

On the engine - You might not believe this, or maybe you will - when I was doing my sufficiency on early EFI systems, I read through a ton of SAE whitepapers in the library. I kept stumbling on fascinating articles. Eventually, I got to 90s stuff and I remember distinctly reading about sending an ionization current to the spark plugs and basically monitoring combustion by the transient response of that current flow. Here is a nice write-up I found:
http://www.delphi.com/pdf/e/ign_ion_cur.pdf

No surprise, it's Delphi. This is all related to GM and the Ecotec, I'm sure.

Not to go off on a tangent, but in terms of advanced engine management, the Chrysler Hemi is a speed density engine, meaning no mass airflow sensor. There is electronic throttle control and the PCM actually reads the throttle input and commands an engine torque. This works well with the MDS (multiple displacement system) going to 4 cylinder mode during cruise, as you would simply maintain constant pressure on the gas (torque demand) and when the engine cuts 4 cylinders, the PCM says "well I need the same torque, since the gas hasn't moved, so I'll open the throttle blade a little more." Instead of having a nasty array of lookup tables for V8 -> V4 operation, it just calculates torque demand...pretty cool. Anyway...

I agree on the RPM thing. That engine seems to be more about torque than crazy zing-to-redline horsepower. Which is nice, neither of my cars are really redline overachievers either, though the camaro is happy to meet its 5800rpm rev limited just before a shift. I think the thing I found most unnatural about the engine is that it DOES have the good torque output, which typically suggest you wouldn't need to downshift (like a larger engine), but it's not available NOW, instead a few moments after NOW, which typically suggests downshifting (like on a smaller engine). So I guess I found it hard to figure out what was best. I agree, not downshifting in that case would be more effective.

I don't know that much about power steering systems. I think when you provide a torque input to the steering shaft, you're kind of leaning on a pressure valve (called a spool valve in a steering box, may be the same in a rack) to allow hydraulic pressure from the pump to act on the steering gear (or rack). I think the rate of the spring that this valve acts against is key in determining steering effort. Neither of my cars have variable speed (or rpm) assist. The camaro is really firm, and the caprice is just kinda firm. My ideal, of course, is pinky steering in the parking lot, and nice, heavily weighted action at speed, especially at triple digits. I don't see why the level of P/S boost couldn't be PCM controlled, such that when there is heavy throttle input, it firms up the steering to act against torque steer. Actually, with these new electric power assist cars coming out, seems like it'd be easy to simply have the system counter-act torque steer for you. I know some high line car already uses a technique like this, but for cross winds (it's RWD). It might be a Lexus, but it might not.

The M20 I was referring to is the 2.5L I6. Oddly, the long-stroke low-output 2.7L has the same engine name. The M3 would have been S-something, not M. Never driven that one, but the E30 people tend to drool on it. That car had a lot of aluminum suspension components, and basically a perfect 50/50 weight dist.

The maxima I am referring to is my mom's 96 SE 5-speed. They trap like 90-93mph in the 1/4 mile stock, with low 15 second ETs. Maybe your car would walk it sooner. It's just that you can shift the maxima a little quicker and you get 205lb-ft of naturally aspirated torque. It seems like it would walk away in the lower gears, the power delivery is pretty nice in that VQ30DE. But your 3rd is strong, stronger than my mom's if my SOTP-memory is functioning. Against adam's 02, off the line, I think he'd have you (and my mom's car) until 60 at least. We'll just have to arrange something. My caprice could probably put up a fight through your first gear and then it'd be Saab taillights for me.