27th Aug 2008, 17:20
Guys, the engine is torquey, but you can't BOG it, ie. try to jump 20mph in 6th going 45mph with the RPMs at 1800. If you do that, you will force the engine and cause it to ping or knock, even with high octane gas. That it because this engine produces V8 torque with only 4 cylinders, which means at low RPM and trying to boost it in a high gear will cause twice the combustion pressures than a V8 doing the same thing. The ECU doesn't like hearing any knock and will do all it can in its power to preserve the engine, which means pulling back the throttle (the accelerator pedal is just a sensor, the ECU ultimately has full control over the throttle) also it will pull back the timing and if you're really lugging the engine then these self-preservation methods will appear as bucking and hesitation. Be kind and downshift if you want to gain speed, don't lug the engine below 3000rpm. That's why that one person experienced the power coming back after a restart. Each time the vehicle is restarted, it listens for knock to occur again, because it's mainly caused by fuel grade. (and it must assume the fuel or conditions are different at each restart)
10th Mar 2011, 19:38
I concur with the original post, and the one just previous to mine.
The stock Speed 6 is a bit squirrely. I too had the issue with hesitation and a rapid, metallic sound during acceleration.
After buying OBDII software that monitors various ECU conditions, I can pretty much definitively say that the hesitation and knock are due to, um, yes, engine "knock" and the subsequent timing retard that the ECU applies when it's trying to protect the motor from blowing up.
The stock engine simply does not allow you to lug it. And this was hard for me, because I'm used to cars with power down low. Never floor it below 3000 rpm and you'll be fine.
For anyone interested in one of these cars (probably hard to find in 2011), one simple bit of advice. Install a Cobb cold air intake and pony up for a Cobb Access port and reprogram your ECU.
This car was a constant frustration for me until I made these mods. It is literally like night and day. The 20+ % increase in torque and horsepower is clearly noticeable. But the real difference is that all that power is available from about 2000rpm on up. And my issues with detonation/ping/knock are almost completely gone. I'm no longer afraid to apply full throttle. The car now pulls right up to redline, too, unlike the stock ECU programming where the motor pretty much died passed 5500rpm.
If you can pick up one of these used for a good price, with low mileage, with a little TLC you can have a pretty amazing stealth racer. I say low mileage, because I have to assume these things blow themselves up well before 100K miles.
The stock suspension and brakes are fine, unless you really drive the car extremely hard. This is a BIG car, and I'm constantly amazed at how well it holds the road. And it's a bulldog in the snow.
The Electronic Stability Control is also very well done -- wish Mazda had done as good a job with the ECU. ;-) It is not overly aggressive, and will not kick in until you really start to go sideways -- which is possible, given that you've got power going to the rear wheels.
In conclusion, this is a car that's a bit hard to love wholeheartedly, but Mazda did put serious (if not always perfect) effort into making a unique automobile -- i.e., the "MazdaSpeed" moniker is not just window dressing. And with a little effort, you can fix the things Mazda didn't get quite right.
I will be sad to see this car go, when its time comes and I have to buy a Subaru. ;-)