4 & 1/2 gears?

[spazspike]

Pretty misleading title, eh?

I picked up my Protege5 last week and continue to break-in slowly without pushing the vehicle. Today was the 'high' speed testing run on Rt. 78 & 287 in NJ. The car never went over 3000rpm/65mph but I noticed something... odd...

The car is a 4-speed "sport" automatic vehicle and I've used traditional automatic for 200+ of the 250 miles on the vehicle. Under normal/gentle acceleration the car goes through it's gears smoothly and quite lively.

15mph... shift... 25mph... shift... 40mph... at 40mph when the car shifts to 4th gear at around 2800/3100rpm everyone is just grand. However somewhere between 50/55mph (approx. 3000rpm) I notice that under the same force of acceleration the RPMs will actually dip to around 2200-2500rpms.

As though it's simulating a switch into 5th. I tried to simulate the situation numerous times and each time it did it. My foot never engaged the pedal harder or lighter.

Any ideas? Is this a gear ratio thing? Better yet... is this natural/good?

 

[mts3]

Torque convertor lockup. Every automatic does it sometime after final gear is engaged. In my Millenia it happens at any speed over 30 mph in 4th.

Strangely I drove a Jetta once (rental) whose TC didn't lockup, and that thing was screaming on the highway. Their 2.0L I4 is a lot louder than ours too.

 

[spazspike]

Tyson, thanks for the reply. So you're saying that this rpm flux is ok and perfectly natural? I was pleasantly surprised at the noise that was heard at 60/65 today, surprisingly quiet. I do imagine it to be a bit buzzy at 75/80 although. However, that won't be till July.

 

[jrodhotrod]

yeah, perfectly normal. The Protege5 has a lockup torque converter. So you'll notice that after you stop accelerating the RPMs will drop slightly.

From Howstuffworks: http://auto.howstuffworks.com/torque-converter.htm

At higher speeds, the transmission catches up to the engine, eventually moving at almost the same speed. Ideally, though, the transmission would move at exactly the same speed as the engine, because this difference in speed wastes power. This is part of the reason why cars with automatic transmissions get worse gas mileage than cars with manual transmissions.

To counter this effect, some cars have a torque converter with a lockup clutch. When the two halves of the torque converter get up to speed, this clutch locks them together, eliminating the slippage and improving efficiency.

 

[spazspike]

Wow... neat website for stupid questions I always find myself asking. Thanks so much for the help guys, as always very quick and excellent responses.

 

[Stealth5]

i thought it might have something to do with overdrive, but maybeim just stupid (probably the case)

 

[fastdrvr23]

i thought it might have something to do with overdrive, but maybeim just stupid (probably the case)

You were in the right ballpark... Just tell yourself that 4th gear is O/D (Which it is) and you'll be good to go. The torque converter locking up feels like you are shifting into another gear, hell, with the RPM's dropping on the tach as well, it seems really similar. All the more reason to get a 5 speed P5, to alleviate any torque converter confusion... lol

One thing I noticed with the Auto P5, the torque converter is quick to unlock with very little throttle applied. I like this, while the gas mileage would suffer eventually, it makes for a nice sporty feeling transmission. Good stuff!

*Edit: I spell like a 3 year old on crack.

 

[spazspike]

No complaints with the tranmission or shifting, the car is extremely peppy. I'm coming off a 2.6l V-6 with about 175-180hp so I was pleasantly surprised. The only weak point is the initial 0-20mph burst and then it quickly reaches 50mph. The "sport" automatic tranmission has proven to be fun but I've promised myself not to abuse it.

 

[Onatrum]

just outta curiosity, does the sport automatic have the button on the gear shifter that turns overdrive off?

It took me a month to notice that button in my automatic, and it was by accident when I bumped it while driving.

 

[Stealth5]

no overdrive control, you just pop it over in manual and you can keep it in 3rd all day long