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Discussion Starter · #1 ·
yet another fault with my Audi a4 1.9 tdi started from cold in morning was OK after i drove it for like 30 seconds car went into limp mode and then in a Que car was shaking like mad while idle looked like it was going to blow up.

i had shut the engine off and started it again like 3 times to get car out of limp mode.

anyone know what it could be i had car on computer before it shows error code.

17964 - Charge Pressure Control: Negative Deviation
P1556 - 35-10 - - - Intermittent

i know this is a fault with turbo or n75 valve but it never shaked before like that when idle

anyone know what the fault is..

thanks
 

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Yep it's a pressure problem. Check the hoses going to the n75. One of them might be disconnected or split. Either that or the n75 is gone, or your have sticking turbo vanes, but if you have that shudder on idle I'd say hers more of a chance a hose is split
 

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It would be worth getting a fresh scan of the ecu as this new fault might have posted another fault code
 

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Discussion Starter · #4 ·
thanks steeve had aa guy come out tday was very helpfull put it on his computer nothing was coming up it didnt even bring up the boost pressure fault up.

he checked all the hoses and pipes all were ok no splits their was some oil on the intercooler which i think is from the turbo but its dried on so it is a slow leak some oil under the egr valve again its a bit dry so a slow leak.

he took 1 of the turbo hoses off and it was filled with black gunk and said all hoses going to turbo need a good clean my turbo is on it way out i think.

but when the car is warm its ok like normal.
 

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There is normally some in the intercooler alright, its no harm. Might be worth cleaning out the intake and turbo hoses and even the turbo itself. See if that changes anything.
 

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I would argue that your turbo is not on the way out, how many miles have you done?

Before the car started cocking up, was it hesitant when you put your foot down? Especially at 60-70?

I would say it's either the vanes sticking on your turbo (either try and clean them yourself £50ish, or get the turbo professionally cleaned £300ish) or the EGR valve being blocked.

I would do it in this order... 1. Clean the EGR valve (ask if you need a diagram/instructions) then, if no luck, 2. try an clean the vanes yourself (I have a link to a cleaner that lots of people on uk-mkivs.net are using) then, if all else fails, 3. get the turbo professionally refurbished (and if it is on the way out, they'll fix it because it'll be taken apart already!)

Hope this helps.
 

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17964 - Charge Pressure Control: Negative Deviation
P1556 - 35-10 - - - Intermittent

Negitive deviation means loss of pressure rather than overboosting. Id start looking again for leaks, vacuum hoses to the n75 and the n75 itself.

Hope youve got somewhere with it!
 

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Then again your poor idle and rough running when cold could have nothing to do with the above fault code! could be 2 faults. Maybe change the temp sensor aswell as its a temp problem. Did the maf make any difference?
 

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Discussion Starter · #10 ·
[quote user="benjie"]

I would argue that your turbo is not on the way out, how many miles have you done?

Before the car started cocking up, was it hesitant when you put your foot down? Especially at 60-70?

I would say it's either the vanes sticking on your turbo (either try and clean them yourself £50ish, or get the turbo professionally cleaned £300ish) or the EGR valve being blocked.

I would do it in this order... 1. Clean the EGR valve (ask if you need a diagram/instructions) then, if no luck, 2. try an clean the vanes yourself (I have a link to a cleaner that lots of people on uk-mkivs.net are using) then, if all else fails, 3. get the turbo professionally refurbished (and if it is on the way out, they'll fix it because it'll be taken apart already!)

Hope this helps.

[/quote]

instrcutions would be good for egr valve m8 had the maf replaced car is ok dont know if it was the map or the aa guy that sprayed cleaner in the turbo pipes.

it was ok before i put my foot down when car was cold it never used to do that was ok but car went into limp mode like once in every 3 months when i put foot down.
 

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Discussion Starter · #11 ·
[quote user="Stevee"]

Then again your poor idle and rough running when cold could have nothing to do with the above fault code! could be 2 faults. Maybe change the temp sensor aswell as its a temp problem. Did the maf make any difference?

[/quote]

the maf did make a bit of a diffrence its just about putting my foot down now iv not been driving it hard fearing it will go into limp mode will see in weeks time how it runs with foot down.

i had the temp sensor replaced about 7 months ago no new faults on me vag .
 

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Discussion Starter · #12 ·
started it from cold this morning put my foot down was OK after 5 seconds straight into limp mode and shaking like mad with no power and smoking looks like i waisted my money on the maf cost me 65.00.

what else could it be this is really getting annoying now.
 

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Its hard to know. Id probably scan again, and start looking into the n75. If you unplug the temp sensor when its cold, how does it run? Any better? You should find it on the thermostat housing.
 

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Its hard to know. Id probably scan again, and start looking into the n75. If you unplug the temp sensor when its cold, how does it run? Any better? You should find it on the thermostat housing.
 

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Discussion Starter · #15 ·
[quote user="Stevee"]

Its hard to know. Id probably scan again, and start looking into the n75. If you unplug the temp sensor when its cold, how does it run? Any better? You should find it on the thermostat housing.

[/quote]

when i first got the car their was a problem with the car over revving vag showed temp sensor faulty replaced but and it was ok after that and now the fault dont come up so i think we can elimnate the temp sensor.

could a drive the car with temp sensor disconnceted will car be ok to run??
 

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hi ive been searching the net with a problem im having with my car and i find your problem is very similar to mine my car is a seat tdi its a 2001 1.4 PD TDI is you engine a PD engine (whats your engine code), my cars the same will only go into limp mode when started from cold and when i accelerate up the road it drops boost and gose into limp mode and chucks up the same error code as yours i turn the ignition off then on and its normal again and when it starts to warm up it never goes into limp mode i have found a way of making it never going into limp mode and thats by driving it a little harder when cold taking it upto 3.5k before changing gear and it drops to just above 2.5k in the next gear, i have to drive it like that till i get into the next village just over 1 mile then i can drive normaly. Ive been trying to find the fault now for the past few weeks ive checked the turbo waste gate, replaced all vacume pipes, replaced the N75, checked all boost pipes cleaned out the MAF and MAP sensors (not replaced) i checked my EGR valve and disconected it so it dose not open (stays sealed) I may be paranoid but im sure this improved it performance ive heared of lots of tdi owners doing this but even after all this it still goes into limp mode if driven nicely from cold, i plugged it in at my work on our diagnostic machine and took it for a drive and on my live data it seems to boost correctly, at idle it shows 14psi (atmospheric pressure) and at full boost 30psi so its boosting 15psi above atmospheric and holds it all the way with no dropping off so im now very confused as to why im getting a low boost fault maybe you can check if your car does'nt go into limp if you drive it a little harder that could possibly confirm if your problems the same as mine.
 

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17964 is the code mate? You have a loss of boost somewhere mate. Did you check the boost pipes down to the intercooler? Also check intercooler for leaks.
 

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Discussion Starter · #19 ·
i took my Audi to a Audi specialist and he said its got to be the turbo and you can hear noise bearings he said in turbo when i accelerate mines if pushed hard when cold will go into limp mode withing 5seconds then even if i restart the engine it will start misfiring and just start to stall with no power at all.

in the morning i have to go really slow if pusehd a little im screwed in morning traffic.
 

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ive checked the pipes but not the intercooler what i cant get my head round is it's holding boost according to the actual data on the diagnostic machine but i had it plugged in when it had warmed up when it drives fine anyway so maybe i will plug it in from cold, i will check intercooler and plug in from cold and report back, the code it kicks up is 17964 - Charge Pressure Control: Negative Deviation. tab99 i guess then yours is nothing like mine i must have miss read the post i was very tiered when i was reading it in the early hours of the morning iguess i will keep trawling the net till i find an answer coz im out of ideas.

Thanks guys
 
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