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Discussion Starter #1
Hi,

Sorry, another N7 question. I've looked a lots of posts, and done a fair bit of testing.

Van has an intermittant boost. Sometimes it drives fine and I can hear the turbo spinning after about 1900/2000 rpm. However, sometimes there is little power and no turbo noise.

Got vagcom and hecked fault codes. Came up with a few, cleared them and drove then tested again. Got the following:

17957/P1549/005449 - Boost Pressure Controle Valve (N75): Open Circuit / Short to Ground
17849 EGR Valve Circ Open/Short to Ground

They indicate something electrical to me? Tested the N75 as in the 'How To' guide, and the resistance between the pins was fine (28 ohms). However, the voltage on the connector when ignition is on is at about 10.7/10.8 volts. Should this be more like 12V?

There has been some grafting on the wiring around here, but Ive checked it out and it *seems* to be all okay.

Could split vacuum pipes be a good place to start, or investigate the wiring more? If new vacuum pipes, where's the best place to get them?

Cheers,
Ollie
 

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Discussion Starter #3
Okay, will check that tomorrow... it's getting cold out there tonight.

Oh, its 2.5TDi AJT.

Cheers for the advice.
 

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Discussion Starter #4
So, checked the resistance between the yelow/black pin at N75 end and the earth at the battery and getting approx 65 ohms. Also checked at the earthing pins on the ecu connector (i assume?? the large ones at one end?? looks like this is where the yellow/black wire goes to...). Also get about 65 ohms between egr blk/ylw cable too.

I'm guessing I should have approx 0 ohms (or there abouts)?? so probably a split in the cable somewhere between the connectors and the ecu connection?

What would be the best way to go about sorting this... just bypass the cables and run an extra cable from the sensor connections to near the end of the cable by the ecu connections? :*

All advice appreciated! T:

Hope this solves my problems, looking forward to having a good drive again!! T:
 

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Sounds like it is too high resistance.

Personally I would pick the loom apart until I found a problem.

Up to you tho - you could run some extra cables to see if it cured it ??

I like to get rid of whatever may be festering tho
 

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Discussion Starter #6
Top work Zmok, all fixed! earth was split from egr/N75.

Have repaired, checked on Vagcom, no fault codes, took it for a spin and haven't stopped smiling! T:T:T:

Thanks!
 

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HI, just seen your thread, where was the earth point, as i have a similar issue, but the vw specialist is saying its no4 injector, however after looking at the engine/injectors after i got home, (and paid them for testing) it doesn't look like they have even disturbed the injectors, as no4 is mega gunky/oily aand no spanner has gone on that (is there another way of testing them without removing anthing?):confused::confused:
The resistance across the elec connector plug (injector side) where it breaks/connects is 0.1ohms, so nothing there? However across the pins on the female side, plug to wiring loom somewhere?? is reading 7.2 ohms??
Any ideas, or ehlp where the earth points are would be great :D
Thanks
2.5tdi, 2003 AJT
Karen
 

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HI, just seen your thread, where was the earth point, as i have a similar issue, but the vw specialist is saying its no4 injector, however after looking at the engine/injectors after i got home, (and paid them for testing) it doesn't look like they have even disturbed the injectors, as no4 is mega gunky/oily aand no spanner has gone on that (is there another way of testing them without removing anthing?):confused::confused:
The resistance across the elec connector plug (injector side) where it breaks/connects is 0.1ohms, so nothing there? However across the pins on the female side, plug to wiring loom somewhere?? is reading 7.2 ohms??
Any ideas, or ehlp where the earth points are would be great :D
Thanks
2.5tdi, 2003 AJT
Karen
All sensor earths go back to the ecu.

What are the fault codes?
 

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Howdy,

I've got a similar issue.

The N75 output test doesn't tick the valve (using super-vag and vag-com) and measuring the voltage on the plug up at the valve outputs 10.8v. So I traced the cables down to the ECU and measured it there. Still, only 10.8v.

The resistance in the cabling is perfect, so that indicates, there is no break. I've got no errors either.

I've checked that the wastegate actuatur isn't ceased up and that there is boost pressure to the N75 valve.

Basically my issue is, that I only see approx 0.5 bar boost up to 2800 and then the turbo kicks in and goes to 0.8 bar boost. The van won't do anymore than around 80 mph and it will struggle from 70-80, where it in reality should do up to 90 mph.

My van is a '99 ACV Syncro with can-bus ECU. Any suggestions are appreciated.

/M
 
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