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basstrom
18-11-2004, 10:31 AM
Hi Guys...

Bit of a tech question... when I'm driving along at a steady speed (eg. between 50 and 70km/h) the engine is steady at about 1300rpm (roughly) then all of a sudden drops just below 1000rpm until you touch the accel. pedal and it picks up again...
sounds like something electrical like a sensor or something?
any ideas?
make sense?

and i cant make it to MM04 :doubt: gotta work....

HyperTF
18-11-2004, 10:45 AM
Sort of sounds like the trans is taking some time to go up to top gear but even then dropping below 1000rpm? that is pretty low isn't it for normal driving? I would be assuming somewhere between 1500 - 2000rpm. Does it go to stall when you become stationary at all? Sounds like the transmission to me or computer playing up.

basstrom
18-11-2004, 10:52 AM
Sort of sounds like the trans is taking some time to go up to top gear but even then dropping below 1000rpm? that is pretty low isn't it for normal driving? I would be assuming somewhere between 1500 - 2000rpm. Does it go to stall when you become stationary at all? Sounds like the transmission to me or computer playing up.

no the trans changes gears fine... when it does drop for the slight second, it's in overdrive... it doesn't stall when i pull up... just crusing along normally and then drops rpm and up again in a slight micro second it's really strange.... ive even tried d/c the battery by resetting the computer.... only thing it done good for it was it's idling smoother and using less fuel now... but yeah mmmmmmm

M4DDOG
18-11-2004, 12:07 PM
Sounds normal to me, mine sits around 1000 doing 50 with OD on, but what you can to test if its electrical:
Turn OD off, if it still does it then it could be electrical
If it doesn't doit with OD off then it's most likely just the car shifting into 4th, what rpm do you idle at? maybe your idle needs adjusting slightly?

shanigans
18-11-2004, 12:25 PM
mine does it driving on the freeway sitting at 100. it will sit at about 25000 and then will drop down to about 20000, does this with overdrive on.

TecoDaN
18-11-2004, 12:45 PM
have a look around your throttle body, possibly a vacuum leak. Does it do strange things while idling?

Also check the sensors around the vicinity of the throttle body that they are all plugged in, I've had similar problems when one of my sensors wasn't plugged in properly.

dingo
18-11-2004, 01:16 PM
Hi Guys...

Bit of a tech question... when I'm driving along at a steady speed (eg. between 50 and 70km/h) the engine is steady at about 1300rpm (roughly) then all of a sudden drops just below 1000rpm until you touch the accel. pedal and it picks up again...
sounds like something electrical like a sensor or something?
any ideas?
make sense?
mate i haven't driven an auto magna in ages... and never a 2nd gen... but the oldies commodore used to drop revs when cruisin at those sorts of speeds to give a minimum effort and minimise fuel consumption....it think its the torque converter locking up.

I'll try and explain but you're probably better looking it up on howstuffworks.com....

the torque converter (TC from here on) is basically a fluid coupling that acts like a bit like a clutch... when ever the engine is accelerating the TC is transferring torque via this fluid connection.... however when crusing, there is no need to have the fluid continually driving and as such the ECU drops the engine revs so that both sides of the TC can be locked together, at higher speeds this may stay locked but at lower speeds when the car needs more torque it will unlock and your rpm will rise again.... comprede?

edit: looks like i kinda hit the mark.... i took the liberty of visiting howstuffworks (click here) (http://auto.howstuffworks.com/torque-converter3.htm) myself to check it... its worth a read for anyone driving auto's!

Gav
18-11-2004, 04:25 PM
mine does it driving on the freeway sitting at 100. it will sit at about 25000 and then will drop down to about 20000, does this with overdrive on.
What do you drive. a Gas Turbine??

M4DDOG
18-11-2004, 08:48 PM
mine does it driving on the freeway sitting at 100. it will sit at about 25000 and then will drop down to about 20000, does this with overdrive on.

Lol 25000 revs? maybe thats your problem :p. try adjusting your idle about 23000 rpm lower and you shouldn't have any problems :bowrofl:

typhoon
28-11-2004, 10:06 AM
I think it's just the trans computer deciding the torque convertor should be locked up, locking it up, then sensing the rpm is too low and umlocking it.
Computers often have economy measures like lock up the torque convertor as soon as possible embedded into them, but they also have overrides that won't allow the engine to labour at too low an rpm, so sometimes they just get a bit confused!
My Skyline would do the exact same thing at 50km/h.

Regards, Andrew.

basstrom
30-11-2004, 01:09 PM
I think it's just the trans computer deciding the torque convertor should be locked up, locking it up, then sensing the rpm is too low and umlocking it.
Computers often have economy measures like lock up the torque convertor as soon as possible embedded into them, but they also have overrides that won't allow the engine to labour at too low an rpm, so sometimes they just get a bit confused!
My Skyline would do the exact same thing at 50km/h.

Regards, Andrew.



do you think there is anyway of making it stop doing it?

doug tl vrx
05-12-2004, 12:10 PM
I've checked with mitsubishi re. this prob a couple of years back. They told me the following:-

1: The Torque Converter should only cut in at speeds above 65km.( 3rd & 4th gears)
2: Also it will not cut in intil engine & Transmission has reached normal operating temp. From my experience, this takes about 10 minutes or 10 kms distant travelled.