hey guys wondering if anyone can help this has stumped my local mechanic too and he doesnt have time at the mo to look it over properly
but on my way home today i overtook one car perfectly fine with the turbo working as normal then went to overtake the next car to find my passat gutless and no acceleration whatsoever thought strange knocked it down a gear and still nothing
so pulled over revved her up sounded normal and wasnt smoking revs up fine in neutral but just no power whatsoever when the turbo shut be cutting in. my mechanic had a brief look in the engine bay whilst i revved it up for him he said he couldnt hear any hissing indicating a hose gone or something but he did say it sounded perfectly normal.
its a 130ps 1.9 pd tdi awx lump
completely baffled by this cos i have no warning lights or anything coming up to say there is something wrong.
i will have a look for fault codes later but hoping someone can help please
now have fault code 17964/P1556 - Charge Pressure Control: Negative Deviation
but still not sure where to investigate also since having the ignition off and back on i have power at top end of revs just not early on where the turbo should be cutting in
Since I'm from the Jetta camp and only recently moved to the Passats I'll base my answer on the supposition that there are parallel problems...
Given the error code I agree that your turbo seems to be at the root of the problem. Even though this seems to be the case the general rule of diesels is filters first. Your decision of course.
Past filters, then vacuum hoses. Rubber degrades over time and a pinhole will kill you. Same with control diaphragms. If they don't hold vacuum, then there's a problem.
Then the "stop" or home adjustment on the turbo actuator arm. If it's similar to the Jetta, then it's very possibly worn or broken. In the Jetta this will cause the arm to stick which, in turn, causes erratic boost. If this be the case, then there are both temporary and more permanent fixes available. One being a simple plastic cable tie set to limit the control arm from totally homing.
Sorry not to be more Passat oriented but I have a feeling that you'll find that your problem is really fairly minor in nature. If you have a good tech he (or she) will find the problem fairly easily. I might caution that throwing components at the problem will not be a good solution from the standpoint of you wallet nor for the benefit of your Passat.
yer think the jetta shares the same pd tdi lump just mounted differtly i think i have been digging in the engine bay this afternoon and found two vac lines off and not sure if it is doing what it should as when i turn the engine off it opens the egr valve the it closes after a few seconds and tried chasing the vac line past the n75 where it branches off and goes behind the turbo also found that half the plug is missing on the electrical connections to the n75 too but there is also a lot of carbon buildup around that area so still stuck
i have had it up the road and back and it seems to have some boost at high revs but not nearly enough the curious bit is its not smoking but ticks over just fine
Well the issue is now resolved yesterday went to take it to the mechanic left it running for a bit to warm up then shortly on the way to the mechanic itstarted giving a little boost then when I wasnearly with the mechanic it gave me quite a bitmore boost about 80% I would sayleft it with the mechanicand he fiddled aboutwith itand has told me he hzs adjusted values to help itbut apparently my turbo is on its way out hesays there is some movement in the shaft
but anyway its now running better than ever in the time of me owning and he also mentioned some sort of adjustment somewhere on a valve which puzzled me
If I had a brain I would be dangerous sometimes
If anyone reads this it's the n75 leaking off to the airbox
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