Well, been lurking and adding gaslog entries for a while now, and finally have something that is possibly worth posting... possibly. Wife had a late work night, so took the opportunity to do a little "optimum speed" testing. I've theorized about it (at least, for my car), but finally had a moment to test it out. I drive a 2002 Ford ZX2 with the 4-speed automatic (I think it is a kind of CVT-ish thing, but the shifter shows 4 speeds. I have a small air dam, Amsoil 0-20w and a K&N filter. Anyway, here you go:
I've wanted to know what the best speed was for this car, mileage-wise. To that end, I went up and down a 1.5 mile stretch of road near my home, resetting the Scanguage trip MPG after I got up to the testing speed. The road is two-lane with some straights and some curves, with a fair amount of ups and downs. I'm not sure what the overall elevation change is, but one end of the test section is higher than the other, making "uphill" and a "downhill" runs. I used cruise control for the testing.
I've always speculated that somewhere around 43-45 MPH was the best speed for this automatic car. I think that at 40 MPH, the torque converter wasn't fully locking up (that's a guess). If I had attempted 35 MPH, I'm prettty sure the transmission would have bounced between 3rd and 4th. Plus, I probably would have been run over.
Anyway, I'm happy to have finally tested this out, even on this short section of road. I'm wondering if other owners of automatic cars are experiencing the same things. I won't double post it, but maybe this should go in the automatic section...
I love coming to the site and seeing what the latest information is. What a great place to learn and exchange ideas on what is a very important topic!
Hmmm... I'm sure you're right. It's probably a 4-speed with a very active TC. Really the only reason I put that was information from a website that I can't find anymore that said something to that effect. It really is an odd transmission... sometimes you can accelerate from 10 or 15 MPH to 55 or so, without the tachometer moving more than a couple hundred RPM. Anybody know for sure if this is even a lockup TC? And a speed?
It's most definately a lockup converter. As for the speed, you're probably right. Most automatics will lock the TC around 40-45 at part throttle but it doesn't take much to get it out of lock that low. 45 sounds about right for a speed that goes in to and keeps tc lock.
I have a 99 zx2 and i have found that it locksup at 42 mph. I too sometime think is a cvt cause the engine rpm's don't seem to vary much while accelerating I can keep at 2100-2200 and watch my speedo rise and rpm's stay the same. i'm using the rpm readout on the scanguage not the indash tach.
Most automatics act like that at light throttle. My 88 cressida, the 90, both the family buicks, most of the cars I've driven at work (I work in a shop so that's quite a few) usually 1st is noticeable but others just sorta slide by.
1991 Toyota Pickup 22R-E 2.4 I4/5 speed
1990 Toyota Cressida 7M-GE 3.0 I6/5-speed manual
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