please help steptronic fault

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locky2501
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please help steptronic fault

Post by locky2501 » Mon Feb 15, 2016 4:18 pm

hi ive recently bought a 2001 mgf freestyle steptronic all was going well sailed through its mot with no problems but now I have
a nightmare on my hands will try and explain
set off in morning all ok travel aproxx 8 miles to work stop at junction then the fun begins
pull away and the car seems to go into the highest gear possible so basically nearly stalls but if you carry on accelerating eventually picks up speed however if you release your foot from accelerator if almosts chucks you threw the window screen as puts the car into a lower gear and attempt to go through the gears again after doing this a few times on longer journeys the car seems to settle down abit I have no lights on dash showing a fault ive also tried in manual this is an improvement but seems to select the wrong half of the gear so jumps down and accelerates it does that all the way upto 6th so far I have checked gear oil level which is clean and on the mark when at temperature and also plug under car which is clean and dry can anyone say they have had this issue
many thanks tim

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Mykel
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Re: please help steptronic fault

Post by Mykel » Mon Feb 15, 2016 8:39 pm

Uh, Tim, some punctuation might help to better understand your post. ;) :lol:

It might actually be a problem in the gearbox itself, a fault in the ratio control motor to be precise. But my first port of call before attacking the gearbox itself is to check whether the TBS (throttle position sensor, aka throttle potentiometer) is giving the correct values. This can be read with many OBD readers, a TestBook or the really great PScan device.

Next thing to check would be the secondary road speed sensor located in the diff housing. This one is mounted close to the sensor for the speedo, about 5 kms to the left and fitted at an angle. Check the wiring, to actually test the sensor you would probably need a TestBook; if available, try another sensor.

Should the ratio control motor come out as the preferred suspect, the following procedure can be carried out to confirm its state (taken from the CVT handbook):
- Turn the ignition off and wait 10 mins for the Engine Control Unit (ECU) to power down.
- Unplug the Gearbox Interface Unit (GIU) connector and use a multi-meter to measure resistance across pins 5 - 6 and 7 - 8. The reading should be between 18-30 ohms for both. The GIU is located in the boot behind the carpet on the n/s wall, close to the rear light cluster.
giu connector.png
- If a reading cannot be obtained, try reading the resistance on the male transmission connector (across pins E - F and H -B). If you get the proper readings, there is a wiring fault.
cvt gearbox.png
cvt gearbox.png (47.12 KiB) Viewed 1283 times
- If there are no readings at the transmission connector either, the motor is assumed to be faulty.

Hope that helps …
Michael
MGTF:
2004 TF 135 in Monogram Spectre, black leather, RHD
MGZR:
2001 ZR 160 in Solar Red, LHD, LPG conv
Classic:
1972 MG Midget MkIII RWA in Blaze Red
MGF Register regional rep for Germany -- germany@mgfregister.org

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talkingcars
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Re: please help steptronic fault

Post by talkingcars » Mon Feb 15, 2016 9:47 pm

Hi and welcome to the forum

Sorry I have no idea about the gearbox but the www.pscan.eu reads the steppy.

James
Home to black Alfa 159 3.2 V6 Q4, blue MGZR160, green MGF VVC and grey MGF 1.8i, and red MG Maestro T16.

MGF chatting on the Register and at http://www.the-t-bar.com

locky2501
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Re: please help steptronic fault

Post by locky2501 » Tue Feb 16, 2016 4:46 pm

thanks will look into it

pscan.eu
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Re: please help steptronic fault

Post by pscan.eu » Tue Feb 16, 2016 7:58 pm

where roughly in "east Anglia" are you?

pscan.eu will talk the engine ECU but it does not yet do the gearbox. One day it will though and hopefully not too long.

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tlonberg
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Re: please help steptronic fault

Post by tlonberg » Wed Feb 17, 2016 7:33 am

Your gearbox is going into a emergency "limp home"-mode.
First things first, change the 10A fuse next to the gearbox GIU located on the left hand side in the boot, under the carpet.

Image

Does the display in the dashboard and the display next to the gear selector show the selected gear (PRND)?
What about S, sport mode?
If PRND does not show, but S does, you may have a problem with the rainbow switch located next to the gear selector.
This is an easy fix.

1. Remove radio, remove gear knob (set gear selector in D and pull firmly towards you), remove center console trim and unplug all gauges and switches mounted to it to expose the gear selector mechanism.
2. Unscrew and unplug the rainbow switch located on the right hand side.
3. Disassemble the rainbow switch and clean all metal parts to ensure good electrical contact.
4. Mount everything back.

Image

Image
Regards
Thomas

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Mykel
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Re: please help steptronic fault

Post by Mykel » Wed Feb 17, 2016 9:00 am

tlonberg wrote:Your gearbox is going into a emergency "limp home"-mode.
I doubt this is the case, Thomas. When the Em-CVT goes into safe mode the engine is usually revving at 2,500 to 2,800 rpm all the time, the PRND display in the odometer wouldn’t work and the gearbox fault light would come on. I honestly think the sensor readings are wrong and the GIU simply tries to adapt the ratios accordingly.
MGTF:
2004 TF 135 in Monogram Spectre, black leather, RHD
MGZR:
2001 ZR 160 in Solar Red, LHD, LPG conv
Classic:
1972 MG Midget MkIII RWA in Blaze Red
MGF Register regional rep for Germany -- germany@mgfregister.org

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tlonberg
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Re: please help steptronic fault

Post by tlonberg » Wed Feb 17, 2016 5:39 pm

Mykel wrote:
tlonberg wrote:Your gearbox is going into a emergency "limp home"-mode.
I doubt this is the case, Thomas. When the Em-CVT goes into safe mode the engine is usually revving at 2,500 to 2,800 rpm all the time, the PRND display in the odometer wouldn’t work and the gearbox fault light would come on. I honestly think the sensor readings are wrong and the GIU simply tries to adapt the ratios accordingly.
Yes, you are right Mykel, there was a gearbox fault indicator on those I've looked at, and it is clearly stated by locky2501 that there is no lights in his dashboard indicating a fault. Also the ones I looked at had high revs, not low revs as locky2501 describes.
So you can ignore my advice, but good luck anyway. :)
Regards
Thomas

locky2501
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Re: please help steptronic fault

Post by locky2501 » Sat Feb 20, 2016 11:11 am

checked the fuse in boot that's ok ,why does it drive ok when cold but soon as starts to get warm goes into meltdown

pscan.eu
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Re: please help steptronic fault

Post by pscan.eu » Sat Feb 20, 2016 12:39 pm

Is the idle speed correct when it's warm? I have seen a few cars with air leaks which will idle okay when cold but as they warm the idle stepper goes to zero and then cannot close any more, which means that the ECU looses control of the idle. On our diagnostic tool the interesting parameters are "stepper position" and "idle error".

I don't suppose that this would have much effect on the gearbox as it should only affect idling, but I'm just trying to think of things that change as an engine warms up.

Also, if you are not too far away I will visit you with our T4 and have a look if you want, which is why I'm asking what part of East Anglia you are at.

locky2501
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Re: please help steptronic fault

Post by locky2501 » Sun Feb 21, 2016 10:48 pm

market deeping only thing I can add to fault is you can drive at say 30 mph for say half an hour but soon as you take your foot of the gas and reapply then that's when the fault starts

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Mykel
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Re: please help steptronic fault

Post by Mykel » Sun Feb 21, 2016 11:47 pm

Check the throttle position sensor.
MGTF:
2004 TF 135 in Monogram Spectre, black leather, RHD
MGZR:
2001 ZR 160 in Solar Red, LHD, LPG conv
Classic:
1972 MG Midget MkIII RWA in Blaze Red
MGF Register regional rep for Germany -- germany@mgfregister.org

locky2501
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Joined: Mon Feb 15, 2016 4:03 pm
MGF Register Region: East Anglia

Re: please help steptronic fault

Post by locky2501 » Mon Feb 22, 2016 6:53 pm

ok ive found a work round to the fault
after a short journey and you know that the fault is imminent soon as you feel the car under torque ie its gone from 2nd to 6th if you back of the throttle and feather it back in it drives normally again does this indicate anything ???????

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Mykel
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Re: please help steptronic fault

Post by Mykel » Mon Feb 22, 2016 9:18 pm

I can only repeat myself:
Mykel wrote:Check the throttle position sensor.
MGTF:
2004 TF 135 in Monogram Spectre, black leather, RHD
MGZR:
2001 ZR 160 in Solar Red, LHD, LPG conv
Classic:
1972 MG Midget MkIII RWA in Blaze Red
MGF Register regional rep for Germany -- germany@mgfregister.org

pscan.eu
Posts: 135
Joined: Sun Apr 14, 2013 9:32 pm
MGF Register Region: South East

Re: please help steptronic fault

Post by pscan.eu » Mon Feb 22, 2016 9:49 pm

I need to visit Peterborough at some point. I don't think it's far from you.

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