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Old 03-28-2008, 05:22 PM
Ishniknork's Avatar
Ishniknork Ishniknork is offline
I hate doing dishes
Location: Ft. Worth, TX
 
Join Date: Aug 2005
Posts: 2,900
Mein Auto: '05 X3 3.0i
Quote:
Originally Posted by datawx View Post
Kicking down from 2000 RPM in light throttle driving the vehicle will start to surge, if you nail it it clears. Also it will hold in gear sometimes at 3000 RPM on flat ground for some time.

OK this will get in depth........rolling down the road at 2000 rpm at say 40 MPH and you come to a slight hill or just want to go a tiny bit faster so you ease on the gas and you get what i call a half kick down......the revs seem to do a slow kick down to take the RPM to 3000...if you keep easing on the gas very slowly so the engine is under load and you want it to pull just a little harder the engine feels like its miss firing. He egg shaped wheel feeling. I can hold this feeling right through to 4500/5000 RPM if i keep easing on the gas. Sometimes the feeling is quite violent. It will jerk me in the seat back wards and forwards! (no rude comments please) The feeling is like a miss fire of the engine or a pulsing/surging sensation.

Yesterday after picking the car up from the dealer i thought they had it fixed but this time i was passing another truck at 70-80 MPH and in that half kick down area of the tranni it started again. Now i can re-produce it at the 2000 - 3000 RPM again. The RPM needle will appear to pulse with the feeling.

I have though for a while now that this may be a tranni issue. It's almost as if the engine and tranni are having a battle as to where the shifts should take place......change now....no no hold on a second.....CHANGE NOW......NO NOT YET.

While this jerking is happening in my kinda half kick down phase.....if you floor the gas it will clear instantly and just pull hard as it should or kick own again and be fine.

Hope this make sense and you get my message.
Ah, yes it does make more sense now. I know that point you're talking about. That's the point, right about 40 mph, that the torque converter will lock up if there is little load on the engine.

AzNM hit it on the head:
Quote:
Originally Posted by AzNMpower32
It sounds like the "half kickdown" is merely the torque converter unlocking. At 40-45mph in 4th gear, the rpm level should be 2250rpm-ish. In D/SD, if you encounter a hill while at this speed, the revs will jump because the torque converter, previously locked, is unlocked to give you more torque. This is normal behaviour for the 5-speed automatic.
I'm not saying you don't have a problem, sounds like you do. You seem to be able to "teeter-totter" right on the break point of the converter lock and un-lock. That's very odd indeed What really gets me is it doing that while passing at 70-80 mph when the converter should be locked. I'm thinking it could be a software problem or maybe the electronic throttle control is malfunctioning.

I'm going to try and duplicate this behavior in my X3 just to see if I can. I know a long, gentle hill to try it on. I'll let you know what happens.
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'05 X3 3.0i Alpine White/Gray Leather/Alum. Trim
Sport/Steptronic/Servotronic/Panoramic
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