limp mode - vw Passat Tdi

Honest John Back Room » Technical matters
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Fri 16 Feb 2007 10:18
limp mode - vw Passat Tdi - nkosi bob
Had a new maf sensor fitted to my vw Passat Tdi 115bhp pd about 8 months ago---- just coming on to the motorway the car lost all power, would only reach 2000 rpm---I switched the ignition off --then on and power came back ----that was about a week ago and the car has been fine since---any suggestions would be appreciated

{car details added to subject header to make post less vague - DD}
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Fri 16 Feb 2007 11:02
limp mode - vw Passat Tdi - Hamsafar
You would need to have the fault codes read. It could be something as simple as a brake pedal sensor.
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Fri 2 Mar 2007 09:24
re-limp Mode - nkosi bob
I lost power on my passat Tdi 115bhp PD briefly---I swiched the ignition off ,then on and all was fine---still is. I put it in for a map reading and the only error that came up was "overboost "-------remedy ,a leaking, or loose air hose. I checked all the hoses and the inter cooler but found nothing. What I did find was next to my MAF sensor there is another small sensor/switch with two small air pipes attatched---one of the pipes was loose, so I am hoping this was the problem---anybody have any idea what the switch is for
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Fri 2 Mar 2007 11:40
re-limp Mode - craig-pd130
I believe that's the solenoid which controls the anti-shudder valve (closes an airflap in the intake when you switch off to kill the engine quicker)

The EGR and boost control systems on the PD motors are all vacuum controlled, if a vac tube of connection is loose / leaking you'll get all sorts of funny problems, which would explain the limp mode.

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Fri 2 Mar 2007 22:11
limp mode - vw Passat Tdi - mini, pug, landy, Andy
this could be our old freind the 109 relay

this is the main engine management relay VW made loads of them that had dry solder joints inside that eventually fracture givving an intermittent fault manifesting itself with the engine cutting out or loosing lots of power. there is a way to recognise if you have the modified type of relay that solved the problem but im not sure what it is

this can also happen on VW petrol models and the realy is number 30

99% of the time the fault will not generate a fault code and very often restarting the car be as if noting was ever wrong. however if it were to happen in lane 3 of a busy M-way this would not be good
--
best regards,
andy
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Sat 3 Mar 2007 10:35
limp mode - vw Passat Tdi - dieselhead
The vacuum hose to the VNT turbo is prone to failure - basically the vacuum supply from the brake servo is increased (from electronically controlled valve) with engine power to prevent the turbo overboosting. If the hose collapses the VNT actuator doesn't move enough and the engine is shut down. Worth spraying the linkage with wd40 and checking the hose.
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