why am i so unlucky with TDIs

I have had 3 different polo saloon tdi cars in the past 2 years and each one has had turbo issues and im starting to loose faith !! so my latest purchase is a immaculate 2001 sky blue polo saloon 1.9 TDI with the ASV code 110bhp engine . It has had 1 owner who has serviced it every year at VW , cambelt change 8000 miles ago and only done 68000 miles!! ,, so drove it 200 miles back from seller . running good boosting as it should .. but .. when i floor the car in 5th gear at 4000rpm ish the turbo cut out .. so i scanned the ecu and 17958 code came up .. i changed the N75 valve .. still overboosting . then i checked the boost pipes and noticed a split in one of the pipes ! BINGO .. replaced it and another pipe that was worn . Took the car for a spin and it boosts great with no cut out and fault code has gone . .. however ... the turbo is making the dreaded juddering noise when i let off gas pedal !! iv had this before and i understand that it judders because of back pressure from spooling turbo , people think this sounds cool but its not good for the turbo ! i did press the actuator lever once to test stiffness while i replaced the pipes and it felt ok . could i have maybe made it stick by manually pressing it down for example .. vains could be sticking and iv forced it to stick even more creating the back pressure ?? i will clean turbo with oven cleaner but just want to know if anyone has had the Turbo flutter noise and what was causing it ??? i dont understand how replacing 2 pipes has caused it ?? any help would be amazing

It is possible you still have a boost leak somewhere. Do you have the factory air cleaner still on the car?

dannib89 said:

Why am i so unlucky with TDIs?

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Probably because you are relying on luck rather than sound maintenance practices.

http://wiki.ross-tech.com/wiki/index.php/17958/P1550/005456 did not direct you to replace the N-75 valve. The intent with a code is to diagnose why the ECU set the code.

A VG place to start when diagnosing this code is to check the integrity of the vacuum system with this: http://www.tooldiscounter.com/ItemD...MIstO1hrit1wIVR2p-Ch1mZQrLEAQYASABEgJePPD_BwE . Pull the hose off of the vacuum pump and pump the entire system down and see how long the entire system holds a vacuum. If it leaks down fairly quickly, there is a leak somewhere and you have to isolate the different parts of the system to find it.

A vacuum system that is in good condition will hold a vacuum for a long time.

Nevada_TDI said:

It is possible you still have a boost leak somewhere. Do you have the factory air cleaner still on the car?

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The symptoms and code don't indicate either one. Best guess is a boost control (vacuum) issue.

Ol'Rattler said:

Probably because you are relying on luck rather than sound maintenance practices.

http://wiki.ross-tech.com/wiki/index.php/17958/P1550/005456 did not direct you to replace the N-75 valve. The intent with a code is to diagnose why the ECU set the code.

A VG place to start when diagnosing this code is to check the integrity of the vacuum system with this: http://www.tooldiscounter.com/ItemD...MIstO1hrit1wIVR2p-Ch1mZQrLEAQYASABEgJePPD_BwE . Pull the hose off of the vacuum pump and pump the entire system down and see how long the entire system holds a vacuum. If it leaks down fairly quickly, there is a leak somewhere and you have to isolate the different parts of the system to find it.

A vacuum system that is in good condition will hold a vacuum for a long time.

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thank you sir i will do the test to see how its holding pressure , will the turbo/actuator flutter cause any damage if i continue driving it until issue is resolved ?,

its not good for a turbo to see any pressure or force other than the one it creates by compressing air. What your telling us means that this was a problem for a while and was masked by a few boost leaks that let the pressure leak out rather than back up the turbo. its not going to kill the turbo unless you dont fix it and run for another 20+K miles. 1000 miles doing this is not going to kill it but probably will ware it out a bit and shorten its life toward the end its putting pressure against the journal bearing on the back side where its not supposed to wear constantly. Your probably fine for a few hundred like that. would defiantly inspect/ clean/ fix the vains and the actuator. Might have a boost leak in the "vacuum" l*boost line going to the actuator. check all the vac *boost lines, going into the ecu, n75, airbox etc... Do you go into limp mode at all? over boosting for a few times will set you into limp mode. From my understanding, your not hurting the car because if you were to, limp mode would kick in. When you get the turbo out, measure the side play. you should have some and your going to have to check the specs for your turbo but there should be almost no end to end play. some turbos do but again your going to have to check on that one for your application. Do you have the stock airbox? if you dont, put it back in.

dannib89 said:

thank you sir i will do the test to see how its holding pressure , will the turbo/actuator flutter cause any damage if i continue driving it until issue is resolved ?,

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It shouldn't, if it's minor. But if it flutters hard, could be something else.

dannib89 said:

thank you sir i will do the test to see how its holding pressure , will the turbo/actuator flutter cause any damage if i continue driving it until issue is resolved ?,

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You are checking to see if it holds vacuum, not pressure. Almost forgot. Make sure the turbo actuator moves freely and from stop to stop when you put vacuum to it and then release the vacuum.

Like you were saying, "probably not good on the turbo". I agree. All it would take for the wrong event to happen once to destroy the turbo. Think of the flutter as the turbo's compressor getting jack hammered by boost air and if the flutter become extreme enough, it could destroy the compressor. Best I can offer is to fix it sooner than later.

thanks guys iv ordered the correct tool and will check vacuum when it arrives. will also put some oven cleaner in turbo to loosen it up , hopefully i get it sorted sick of having boost issues with TDIs

dannib89 said:

thanks guys iv ordered the correct tool and will check vacuum when it arrives. will also put some oven cleaner in turbo to loosen it up , hopefully i get it sorted sick of having boost issues with TDIs

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A very bad idea. Oven cleaners is very caustic and loves to destroy aluminum.
Ask these guy how they know. https://www.jalopyjournal.com/forum/threads/used-oven-cleaner-on-aluminum-heads.512338/

Ol'Rattler said:

A very bad idea. Oven cleaners is very caustic and loves to destroy aluminum.
Ask these guy how they know. https://www.jalopyjournal.com/forum/threads/used-oven-cleaner-on-aluminum-heads.512338/

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I'm pretty sure he means to spray it into the exhaust (iron/steel) side.
It's a common method of freeing up the vanes without disassembly.

I guess you learn something new every day. I Googled some some pics and sure enough, the exhaust turbine and housing don't look to have any aluminum in them. My bad.

So, I would amend my caution to dis-connect the inlet and outlet to the exhaust turbine so that you can completely rinse the oven cleaner out with water and not get any oven cleaner into the cat.

Yes it’s exhaust side I have done it before and it works pretty well , I believe it’s more common here in the uk ���� maybe why you haven’t heard of it. I will make sure I don’t get any in the cat . Quick question where is the best place to hook up my pump to test vaccume ?

I had heard of the oven cleaner thing but never took it seriously because of the ugly damage oven cleaner does to aluminum. Do you have Ultra Low Sulfur Diesel? (15PPM in the USA) Until we got it in 2007, deposits were a lot more common. https://en.wikipedia.org/wiki/Ultra-low-sulfur_diesel

Start by disconnecting the vacuum tube from the vacuum pump and then pull full vacuum on the entire system. It will take a little bit of time because you will be drawing vacuum on the vacuum reservoir and the brake booster.

Once the system is pumped down and stabilize wait and see if the vacuum bleeds off. If vacuum doesn't leak down within about 10 minutes the entire system is probably leak free and vacuum leaks aren't an issue.

If the system does leak down, you would isolate different parts of the system by disconnecting vacuum lines and plugging them. Also you would move the MiteyVac to different parts of the system and check individual components like the turbo actuator, brake booster, EGR valve etc.

Not knowing exactly what component your vacuum system has and their layout does make arm chair trouble shooting kinda tough. If you have a map of the vacuum hoses, It would help you figure out were to go next. IIRK there should be a vacuum hose map under the hood somewhere. (Bonnet?)

Oops, forgot this: To check the vacuum pump, connect the MiteyVac directly to it and run the engine. IDKFS but pulling a vacuum on the vacuum pump with it not turning would probably allow vacuum to leak through the pump.

HUH? The OP never mentioned anything about mileage.........

Oh. I understand your post know, you meant total car miles not MPG.
Maintenance and car operating conditions are very important as you alluded to. My wifes 2011 Camry and my GD's 2007 Hyundai accent both have about 85K miles on them.

The Camry has zero issues because for the most part the maintenance has been kept up and it's mostly had a mix of freeway and local miles. (bought used in 2015).

The Hyundai however, (also bought used) was most likely rarely driven and when I pulled the head off for a burnt valve, it looked like it had never had an oil change. The crankcase vent system was completely clogged to the extent that normally vented blowby was most likely escaping past the rings and valve guide seals.

Since I cleaned everything up, replaced the rings and had the burnt valve and valve guide seals replaced and had the valves ground it runs really well now and it looks like it will be using 1 quart of oil in about 3 to 4 K miles were before it was using about 9 to 12 quarts of oil every 3 to 4 K miles.

What the head scratcher was that with a clogged PCV system it usually pressurizes the sump which causes gaskets to leak. On this car there were no tell tale signs of external oil leaks.

hello all ,, so im from the uk yes and all vehicles are in miles here so my polo has just hit 69,000 miles not kms and i have just checked the old bills, a bill from 21st october 2014 at 61297 miles saying replaced cambelt kit and auxiliary drive belt so i assume the water pump is usually included in a cambelt kit. so as you can see it has only done around 8000 miles from 2014 and this pattern continues in the old bills. Russee11 your correct the vehicle has had a older gent owner who has rarely driven the car so this may mean build up of carbon in turbo ?
i had a quick look into the side of EGR with pipe off with my torch (flash-light) and it looked black but not fully blocked up however i know i need to remove the EGR valve and intake manifold to clean correctly , the car has been serviced atleast every 10,000 miles as i have the old bills and stamps from dealerships.
i connected hand pump up too the pipe going to the actuator on the turbo and pumped it up , actuator rod moved ok but made a squeaking noise when releasing (i think i will need to clean vains in turbo and lube the actuator rod)
when i connect hand pump to vacuum pump do i T-piece it in or pull the pipe off and connect hand pump to it ?
i pumped air into the pipe going too actuator and after 30 mins it lost half the pressure ? sign of a leak ? or is it my cheap hand pump ?

THanks

Rrusse11 said:

dannib89,
Just pull the actuator hose off and plug into the acutator. If it's squeaking on release, it sounds like your vanes are sooted up. May respond to the oven cleaner method.
A dealer service may mean they changed the oil, and that's about it.
The timing/cambelt change should be good, but it is now 3 years old.
The filters are ez to do yourself. Clean the turbo, manifold and EGR and drive it. Blow some of the cobwebs out when you do, gently at first I'd recommend. Gradually work it up to the ocassional 4k rpm after you've got it sorted. The injectors are probably a bit dirty, do some research on Diesel Purge when you do the fuel filter.
Brakes, bushings, shocks, it goes on and on. TDIs will go a long time, but you do have to get all the systems sorted out. And it is after all a 15yr old vehicle. Stuff gets old and crusty and brittle after a certain age, ask me how I know. {;o)
Cheers!

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thank you for your help sir , i have all new brake pads and discs so going to fit them as they need replacing . i will connect the hand vac direct too the actuator to rule out pipe and test the rod movement (should it loose pressure after 30 mins ?) i tested the hand pump and it holds fine so thats not faulty. I will be replacing all the vac lines as i have noticed they rub and split often on TDis but would like to know exactly where the leak is . I know how to use diesel purge and will do this to give the injectors a blast (i also have a fuel additive called millers max diesel that you put into the tank and it works a treat .
The last service was done around 500 miles ago at 68534 on the 08/11/16 (i realized when i visited Louisiana that you change the day and month in the states so 11/08/16?) this service included all filters oil and engine flush (photo attached)
when i get the intake manifold off would you recommend the petrol and blow torch metod lol? link below ..
https://www.youtube.com/watch?v=xIijYgvxW0g

bill for service below..
https://ibb.co/kcanLw

My polo saloon 6k (are there many of these in the states ? they are not popular here in the uk but did very well in Brazil)
https://ibb.co/nR2ytG
https://ibb.co/ivCytG

Rrusse11 said:

danni,

If your system is holding vacuum for 30 minutes, I'd say that's pretty good, but by all means go through and replace the lines. Not difficult or expensive. I've just bought the tubing myself to do same.

I wasn't as aggressive with intake cleaning as oxy/acetylene. But with care and caution, I'm sure it'll work. I attacked it chemically first and then some mineral turps with a propane torch. It's a messy time consuming job but well worth it in the end.

So in a year your new car did 500 miles? If the photos are of your car, it must have been garaged, paint looks good! Can't comment much on the "polo" model, looks like a Jetta to me, but others with
much more experience than me can comment on the various models.
I've never been much of a car buff. I just really like the hatchback configuration of the Golf, a small station wagon that holds a lot of stuff when needed.

Keep plugging away, you'll get it sorted!

Cheers,
R*2

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yes its my polo it is very clean not a spot of rust and original paint so i assume it was garaged . thanks for all your help and advice .

so i have removed the intake and EGR. as i thought it was full of carbon build up ! so i cleaned them out and cleaned the turbo with oven cleaner while i had intake off. actuator rod now moves nicely and i sprayed it with silicone spray to protect it . put it all back together and the car pulls perfect with plenty of consistent boost and no flat spots also all codes are gone .. however .. still the stupid compressor surge noise ! i have tried driving it without air filter to rule that out and doesn't help .. so no codes no issues with power at all but still the stupid compressor noise ?? any ideas guys ?

https://m.youtube.com/watch?v=OSY9tJK_Hos

Apparently bad for the turbo , I don’t mind it just don’t want to think it’s causing damage . The cat may be clogged causing the surge I might take it off ,

hello russee11 yes i think there will be some type of blockage in the cat due to maybe broken down internals causing a back pressure . i will change all the vacuum pipes first to rule that out then go for the cat .