very STRANGE running problem!!!!

OK--here is a head scratcher......

car= 2002 Toyota ECHO stick with 5 speed manual-25k miles on car.

on very cold days (ie temp below 25 degress)--there is a drivetrain slippage if I trounce the throttle in third or forth..with rpm above about 3000 rpm....feels like the clutch is slippiong......only does this on very cold days....dealer finds nothing wrong........

above 25, all is ok

problem shows when i merge into fast hi-way traffic (ie merging into hi speed traffic in third or forth gear).

otherwise--car runs perfectly..all service has been done/performed by Toyota dealer. Have noticed this problem since about 12000 miles.

I notice the shifter is a bit notchy going from 1-2.

TX ps--gas mileage= 42-44 mpg-hiway-summer-average speed 65 mph...drops to 38-41 mpg, winter, same driving conditions..mileage checks done very accurately--car is driven conservatively (ie slow acceleration-braking etc).

I have a '04 echo hatch and I think I may have the same problem as you. Is it just when your engine is cold that you experience the surging/lagging? My engine is touchy when it isn't warmed up and it is relatively cold out.

The shifter is notchy throughout all gears. Its just a rocky gearbox.

The only thing I can think of for your lower gas mileage might be that you are losing gas mileage when the car hasn't warmed up yet, because it takes much longer than in summer. I know engines pollute more when they aren't warmed up, but i'm not sure if this would be the cause of your problem. Just a guess.

tx....

my problem is slippage of some type: occurrs only on very cold day (ie below 20 degress F): when i have engine in 4th and speed 55+ and floor accelerator--the engine speeds up as if the clutch is slipping..it does not lag..it races as if something is slipping in drive train (clutch/cv joint etc)..

my gas mileage now (90% hiway driving average spped of 65 mph)= 39-40 mpg (regular gas).

Gearbox very notchy until engine warms up (runs at least 20 minutes).

The slipping is very strange since it occurrs only on very cold days..feels exactly like a slipping clutch.

cat has 29K very carefully drive miles on it..oil changes q. 3K miles (synthetic oil) and conservative driving habits. Mileage in summer (all hi-way) averages abt 43-44 mpg (regular gas),,vs 37-40 same conditions, winter (Massachusetts).

Only mech problem encountered so far= rattling doorlock assembly, driver door.

Car gets washed/waxed every week..no soapy used, only rinsing.

ive changed headlites to 120 watts version (frm JC Whitney)--works great.

wonder if there r any simple performence tweks possible to increase low end torque/power..car bogs below 3500 rpm.