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Discussion Starter #1 (Edited)
This code has come up on the VCDS
7656 - Start of Injection Timing Regulation: Control Deviation P1248 - 35-00 - -

after clearing the fuel shut off solenoid fault just previous with a new solenoid. I can't seem to get the timing to sit still within the lines on the tdi timing graph, it idles like a pig and jumps from 38 to 102 on the graph, anyone else had this problem and resolved it or seen this before. AJT engine.

Cheers Ken
 

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Dear Ken. My father in law seems to have a similar issue as per your description on his T4 westfalia.. The yellow line jumps up and down and engine looses power over 3000 rpm completely. Did you manage to sort your issue out and can you advise how? Many thanks.
 

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Crank position sensor or injector with needle lift sensor.
When you drive does it feel like the brakes have come on- on their own now & again?
 

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Yes it does feel like if the brakes have come on, but this effect starts only at around 2800-3000 rmp. We were measuring the timing while driving and the yellow lined dropped to 0 right when the braking occured. Couldn't these symptoms be caused by N108 valve malfunctioning? We just want to nail down the cause of this behaviour, because error 17656 P1258 - 35-00 is quite a broad one and we don't want to waste money on starting changing all the possible parts linked to this error...
 

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Yes it does feel like if the brakes have come on, but this effect starts only at around 2800-3000 rmp. We were measuring the timing while driving and the yellow lined dropped to 0 right when the braking occured. Couldn't these symptoms be caused by N108 valve malfunctioning? We just want to nail down the cause of this behaviour, because error 17656 P1258 - 35-00 is quite a broad one and we don't want to waste money on starting changing all the possible parts linked to this error...
If the van starts OK then I would point to the needle lift sensor. A whole injector will be required. If the van struggles to start go with the crank sensor. You can test both using a ohmmeter, if you google them you should find what the resistance should be. I can't remember off the top of my head, sorry bud.
 
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