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mu help please

Posted: Thu Jul 24, 2014 3:10 pm
by mr terrano
hi there we have just brought a mu the mrs wants to get into a bit of 4x4ing as well now after a day or to i have noticed that it goes up gears fine but if you button of the gas the revs drop right down straight away then wen you put ur foot back on it there is no pull until the revs then jump back upto the revs that correspond with the speed then it will boggie agane i was thinking speed sensor after abit off research any help or advice would be i also found this on the net also

(It can cause problems but not what you're describing. It seems to me that the clutch pack is faulty or you need to check the transmission fluid level.

The faster the wheel spins, the faster the frequency the wheel magnet moves past the sensor thus the higher speed reading on your speedometer. The vehicle speed sensor counts the revolutions of the transmission output shaft. For a given vehicle, the Transmission Control Module considers a certain number of revolutions to equal a mile. A defective speed sensor can either set off the "S" light or fail to engage the cruise control, which also can affect other system controls. The result is that the TCU thinks the vehicle is running at zero speed from what it’s actually doing. The first thing you notice is an intermittent speedo reading then followed by a transmission error code after decellerating from a moderately high speed. The error codes will reset after every ignition off/on cycle.

Will the transmission shift normally to all gears (1-4, plus lockup) when the speed sensor is broken or removed?

Yes. The transmission will shift up as usual. The VSS is mainly required for a proper downshift such as for descending from a hill. It will also shut off the engine if the speed is excessive. A failed VSS often won't create a limp mode. But most TCU's may go into a "limp mode" when there is a detected fault. The limp mode is usually mistaken for a transmission problem when the transmission refuses to shift. Please check for a stored code)

so am thinking this is the problem any advice is much appreciated

Re: mu help please

Posted: Thu Jul 24, 2014 4:41 pm
by NB42
What year is the Mu? Is it auto or manual? Which engine?

Re: mu help please

Posted: Thu Jul 24, 2014 4:49 pm
by Crash bandicoot
IT's an auto, and my mistral had the same issue since converting the injector pump to mechanical and ditching the engine ecu...
whats the engine ecu got to do with it you ask? the speed sensor.

Since my engine no longer had an operating speed sensor I had to wire up a DPDT switch to get the transmission to lockup the torque converter as it would no longer do it automatically and feed power to the over-run clutch which gives you that engine braking effect when you take your foot of the gas in a manual.

When i say "I had to" I mean i couldn't be arsed getting the speed sensor to talk to the TCU with the ECU no longer being there it was easier to drive it like a truck and operate the over run like engine brakes when required.



So based on that I'd say your over run solenoid is not getting power or the TCU is not getting its signal.

Re: mu help please

Posted: Thu Jul 24, 2014 5:29 pm
by mr terrano
NB42 wrote:What year is the Mu? Is it auto or manual? Which engine?


92 auto 2.8l

Re: mu help please

Posted: Thu Jul 24, 2014 5:31 pm
by mr terrano
Crash bandicoot wrote:IT's an auto, and my mistral had the same issue since converting the injector pump to mechanical and ditching the engine ecu...
whats the engine ecu got to do with it you ask? the speed sensor.

Since my engine no longer had an operating speed sensor I had to wire up a DPDT switch to get the transmission to lockup the torque converter as it would no longer do it automatically and feed power to the over-run clutch which gives you that engine braking effect when you take your foot of the gas in a manual.

When i say "I had to" I mean i couldn't be arsed getting the speed sensor to talk to the TCU with the ECU no longer being there it was easier to drive it like a truck and operate the over run like engine brakes when required.



So based on that I'd say your over run solenoid is not getting power or the TCU is not getting its signal.




thanks bro for the info :D

Re: mu help please

Posted: Fri Jul 25, 2014 12:30 pm
by Mr Revhead