2004 CTT - Loose turbo?

[Zakowsky]

A few questions regarding the turbochargers - there is a tapping sound that comes from the driver side under WOT; it was there for the previous owner as well, and I am pretty sure it is something in the area of the turbo hitting the frame or similar. PO had a new exhaust system put on hoping it would help but it didn’t. When you go under the vehicle and bang on the large exhaust flange where it exits the engine compartment, the passenger side is solid, but the driver’s side moves a bit (~1/4 inch) and you can hear it hit something, thus I assume the noise. Questions I had:

1) Does play at this point suggest something is not attached well upstream at the turbo? Or is there supposed to be some flex in the system?

2) I can’t see up far enough from underneath to see the turbocharger - how do people visually inspect the turbo? Are you supposed to be able to see them after removing the air box? I have a cold air induction system and things are different in there on mine - if I take it all out should I be able to get a visual on it?

3) Seemingly unrelated but maybe not, there are 2 wastegates, one on each turbo, that act independently, correct? It seems that I only hear one on the passenger side opening. This, combined with the looseness has me concerned that something isn’t right on the driver's side. But the engine runs pretty smooth and the boost pressure goes high as it should.

4) I’ve looked at the DIY turbo replacement by SpawnyWippet here and on Rennlist; has anyone else successfully replaced a turbo without dropping the engine?

Thanks for any feedback.

[Zakowsky]

Well I seem to have solved this, in case anyone ever wonders. I did figure out where the flex pipe is (that explains the flex...) and that the catalytic converter is not where I am used to finding it so the turbo is probably fine. It seems the rubber grommet supporting the exhaust is worn on one side and has a lot of play; it has the Fabspeed Turbo Maxflo exhaust system on it, and the alignment of everything is actually not that great. Anyways for testing purposes I jammed a bolt in the grommet to take up the play and the knocking went away. Easy fixes are so great. But I am still curious if anyone has DIY’ed their turbocharger with the engine in; also looking at it more closely, can you see the turbo if you take out the wheel tub plastic? Seems like you might be able to get access that way.

[lewisweller]

4 hours ago, Zakowsky said:

Well I seem to have solved this, in case anyone ever wonders. I did figure out where the flex pipe is (that explains the flex...) and that the catalytic converter is not where I am used to finding it so the turbo is probably fine. It seems the rubber grommet supporting the exhaust is worn on one side and has a lot of play; it has the Fabspeed Turbo Maxflo exhaust system on it, and the alignment of everything is actually not that great. Anyways for testing purposes I jammed a bolt in the grommet to take up the play and the knocking went away. Easy fixes are so great. But I am still curious if anyone has DIY’ed their turbocharger with the engine in; also looking at it more closely, can you see the turbo if you take out the wheel tub plastic? Seems like you might be able to get access that way.

The driver side turbo can be partly viewed by removing the wheel liner and the complete air box. This is the view, you can see the wastegate actuator on the left.

Some more snippets can be seen from under neath. 

[Zakowsky]

Thanks, much appreciated. I think I will take out the tub this weekend and make sure everything looks OK. It’s running pretty good, but there is a kind of fluttering sound when the turbos are at work that I haven’t heard on other turbocharged engines.

[lewisweller]

12 hours ago, Zakowsky said:

Thanks, much appreciated. I think I will take out the tub this weekend and make sure everything looks OK. It’s running pretty good, but there is a kind of fluttering sound when the turbos are at work that I haven’t heard on other turbocharged engines.

On other Vag turbo cars I've owned when you put a cold air intake on it your can hear the Flutter of air noise from the wastegate flap opening and bypassing the exhaust gas around the turbo. The standard air box muffled and mutes this quiet well but intakes don't. 

 

Flutter noise is normally one of both of the diverter valves on our cars. If the diaphragm is split (most likely) or not operating correctly because the vacuum pipe is split or the changeover valve is not functioning correctly they can make strange noises, some describe as honking, this when the boost leaks around the dv and back into the turbo intake pipe. 

A simple test to check the dv is disconnect the T piece of the vacuum pipes which is just to the right side of the throttle Y pipe under the "turbo" cover. Pull apart the vac pipe from the right dv and blow hard, repeat on the open T pipe end also, if you can blow any air through you have a leak or a broken dv.

[Zakowsky]

Thanks - mine does have its fair share of strange sounds. I think the "honk" noise could be there; what was interesting to hear was the other post with the videos of the exhaust system install. Mine sounds similar to the fully modified version from the outside, but quite different inside. Most notably is when the wastegates open there is that classic aftermarket turbo loud air release sound. But again I am not sure of all the mods that were done to mine; maybe there is a different blow off valve setup or something. I need to take a look at my wastegates, DVs and turbos and see if anything is not stock. I tried your test – to bad you can get manuals so easily for all other Porsches except the Cayenne; I have to go over the parts fiches some more to figure what is what. Mine is set up a little different. I believe the red arrow points to the T as in yours – I disconnected it from the solenoid it goes into at the green arrow and blew – there is no leak really, but you can feel what seems like a diaphragm flexing a bit as you increase pressure. Didn’t want to blow too hard and damage something. I took off the line with the blue arrow that also goes to that solenoid and air just free flows through there; I assume that is the vent? I have to go over the diagrams and learn what is where on this. I will try and take a sound clip of it accelerating and post it. Thanks again.

[lewisweller]

1 hour ago, Zakowsky said:

Thanks - mine does have its fair share of strange sounds. I think the "honk" noise could be there; what was interesting to hear was the other post with the videos of the exhaust system install. Mine sounds similar to the fully modified version from the outside, but quite different inside. Most notably is when the wastegates open there is that classic aftermarket turbo loud air release sound. But again I am not sure of all the mods that were done to mine; maybe there is a different blow off valve setup or something. I need to take a look at my wastegates, DVs and turbos and see if anything is not stock. I tried your test – to bad you can get manuals so easily for all other Porsches except the Cayenne; I have to go over the parts fiches some more to figure what is what. Mine is set up a little different. I believe the red arrow points to the T as in yours – I disconnected it from the solenoid it goes into at the green arrow and blew – there is no leak really, but you can feel what seems like a diaphragm flexing a bit as you increase pressure. Didn’t want to blow too hard and damage something. I took off the line with the blue arrow that also goes to that solenoid and air just free flows through there; I assume that is the vent? I have to go over the diagrams and learn what is where on this. I will try and take a sound clip of it accelerating and post it. Thanks again.

My friend You have inadvertently tested the n75 valve and vacuum pipes to each wastegate and NOT the DV's which will be tucked under and to the right of the red arrow 1" and down 2". But not to worry, the blue pipe is indeed the bleed off air return to the turbo inlet so open is correct, the Green is the control pressure air to open the wastegates obviously just splits off at the T red arrow to each turbo wastegate. Now to open the wastegates you need between 7-12psi  and I'm sure you can't blow that hard, so use a air Compressor regulated to 10psi and pulse gently into green arrow pipe, you should hear no air leak at all or bingo you found a problem with either the vac pipes or the wastegate(s) diaphragm split. When you get the air pressure in the green pipe you can hear the wastegates creaking as they move, the sound should be simultaneous both side or something is not right. Again any air leak is going to cause running issues like for example over boost code and limp home reduced performance will start. 

 

To find the DV vac pipe it is this one in my zoom in of your picture dead centre of my first picture running vertically with the mini metal clamp, this runs along the manifold from the change over valve at the back of the engine. At the bottom end of the pipe you will find the T, it's hidden under the intake pipe in your picture. Mine is exposed as I lifted it above and next to the purge valve when I had it all apart, its so easy to check now routinely. 

[John White]

Great info!! I'm still learning how this whole system works!!

[Zakowsky]

Great info indeed; lewisweller, thanks for all the help here. And hah! I found the correct T (perfect zoom on the correct line), right there under the intake pipe. No leaks on the DV’s. I will test the waste gate opening, but first I have to get a better regulated pressure source – I just have a huge air compressor and I don’t trust the accuracy of the pressure regulator that low. Going over the maintenance records again I see that a few years ago they detected a “minor vacuum leak in the waste gate actuator” which was causing some misfiring. Maybe that is happening again. The whole idea of limp home mode is unsettling, and I still don’t have a Durametric cable. But in the mean time I’m charging up the GoPro and will film a clip of with the engine sounds for fun.

[lewisweller]

10 hours ago, Zakowsky said:

Great info indeed; lewisweller, thanks for all the help here. And hah! I found the correct T (perfect zoom on the correct line), right there under the intake pipe. No leaks on the DV’s. I will test the waste gate opening, but first I have to get a better regulated pressure source – I just have a huge air compressor and I don’t trust the accuracy of the pressure regulator that low. Going over the maintenance records again I see that a few years ago they detected a “minor vacuum leak in the waste gate actuator” which was causing some misfiring. Maybe that is happening again. The whole idea of limp home mode is unsettling, and I still don’t have a Durametric cable. But in the mean time I’m charging up the GoPro and will film a clip of with the engine sounds for fun.

Hearing a noise on thursday sounds like a leak only under boost conditions. 

So Today I practised what I preached. Did intake Hill Billy style smoke test through the MAP sensor hole with air box pipes plastic bagged closed, which was fine no leaks, also quickly checked the dv vac pipes no leaks. But when pressurising the wastegate vac pipe from n75 valve could hear loads of air leaking out both sides. Just running my hand along the pipe down to the wastegate could feel the pipe was split almost identically on both side vac pipe. 

Both vac pipes are very brittle I tried to cut of a bit and reconnect but no dice. So jumped in the dad's ford (pos) and headed for the hydraulic pneumatic shop. Found the 6mm id x 13mm od pipe and swap both section either side, lucky it fits nice over the wastegate spigot stub pipe without a clip cos heck I can't get my fat fingers in there let along a tool to fit a clip on the pipe. The best thing is the new pipe allows the smaller pipe section which run up to the T and into n75 to just slide inside and with some "Ear clamps" I bought pinches nicely around to make an air tight seal for just $4. Bargain!

I also replaced that little flexible piece of pipe on the bottom vac pipe of the n75 valve as it broke twice and I couldn't cut it any shorter lol. 

So guys don't buy expensive new pipes from Porsche for $100's just get a size sample and head down to you local hydraulic pneumatic shop. 

 

Also changed the oil and filter today. Oil was very thin and black after just 4k km. Also the filter was full of crap and bit of I don't know what but not metal. I think left over grim from the head gasket job 6 months ago. Glad I did it the filter must have been near blocked by the look of it. I refilled with a "cost effective" German made vw approved brand Ravenol 10w40 as I think this aging engine and it's variocam system required a thicker viscosity as it wears in later life. Being only semi synthetic means a earlier change but here in middle east I never go above 10k and would be changing this oil after another 5-6k km. 

 

Some comments on oils for older ctt would be interesting if anyone cares or has info to share pls?

[ekstroemtj]

Great job!

According your post and the pictures i understand you replaced only the broken sections?  Not the entire line from N75 to wastegate?!

[lewisweller]

11 hours ago, ekstroemtj said:

Great job!

According your post and the pictures i understand you replaced only the broken sections?  Not the entire line from N75 to wastegate?!

Correct thomas the smaller pipe which is 6mm outer dia and 4mm inner dia I reused and just bought the 6mmx13mm pipe to connect to the smaller pipe and down onto the wastegate. Fits nicely and not a squeak of air leak can be heard after. Perfect.

 

Looking forward to driving after rebuilding CV joints and boots tomorrow. Will do a picture and write up of driveshaft rebuild for the sake of it.

 

[lewisweller]

Driveshaft rebuild done today but was rushing my *** off so no pictures at all. Quiet as a mouse now on full locks forward and reverse. Tick box

 

The test drive was great, first time since changing the wastegate to n75 valve flexi pipes that were leaking. Amazing difference in throttle response and pick up. Still is a bit clumsy from low rpm when the boost comes in strong but wow what a different car to drive without this small leak on the wastegate. 

I think the wastegates really play a critical role in how boost is delivered in the lower rpm especially and low early boost periods ie when boost is requested this is when the wastegate is most prevalent in how if it is malfunctioning you will feel it, at high rpm full boost acceleration it's less prevalent to the way the engine behaves. 

I need to find the correct groups on my vagcom to log boost requests vs actual and see if they are far apart. What's still mind boggling is in Park or neutral you rev the engine to 1k and just over 2k and it vibrates to hell, why I have no idea but if I fix this i out my life on it the surging and hesitant acceleration will also be gone. 

[lewisweller]

I got a code!! Driving today gave it some beans and here a weird noise something leaking I think, sounds like a fan belt screeching but it only on high boost not rpm related.

I pulled P1090 code and looking at the O2 sensor on bank 2 it's all over the place jumping up and down. 

First pic is o2 sensors graph with snap open throttle, yellow line is bank 2.

Second picture is at steady idle, look at yellow line of 02 sensor bank 2 going wild. 

Third pic the dtc codes the Vagcom scan shows, ignore the SAI code I disconnected them. 

The maf reading g/s is also low for the idle I noticed. 

Few possibles here, leaky pipe somewhere, dv valve fault, faulty maf or o2 sensor or combination of these hence the noise has to coming from somewhere. 

Haven't time to get dirty today but excited to fix and see if by magic the remaining running hesitation is gone. 

Anyone got experience of P1090 code and weird boost leak screech noise. 

[lewisweller]

Its the AOS diaphragm is split I think, haha I thought it sounded like a balloon when you blow it up and stretch the neck and let the air escape slowly screeeeech, make sense the diaphragm is rubber.

 

I will pop it out later to make sure, now need to buy another one from that BMW website and a air compressor seal and piston ring as well whilst i am at it. .

 

 

 

 

VID_20161101_171405.mp4

Edited November 1, 2016 by lewisweller

[Zakowsky]

Been working for several days solid; have had no time to do anything on the beast. But great write up, thanks lewisweller, sounds like you are making progress! I hope to get at this in a few days.

[Zakowsky]

Finally went to clean the MAF sensors; minor questions – to get out the air tubes holding these is easy on the normally aspirated engine, but the turbo sticks them down at the sides. Do people take out the whole air tube to do this, or just unscrew the sensor? Looks like getting to the inner bolt on the drivers side is a bit tight for room....

 

Passenger side is better

 

Also, can you clean the pressure sensor with MAF cleaner as well? If not, just carb cleaner? Or not to bother?

 

Also, if you unplug them (with the engine off...) do you have to reset any codes afterwards? I still don't have a OBD2 working yet, and will probably clean them attached if there is a risk of that. Thanks!

 

[lewisweller]

50 minutes ago, Zakowsky said:

Finally went to clean the MAF sensors; minor questions – to get out the air tubes holding these is easy on the normally aspirated engine, but the turbo sticks them down at the sides. Do people take out the whole air tube to do this, or just unscrew the sensor? Looks like getting to the inner bolt on the drivers side is a bit tight for room....

 

Passenger side is better

 

Also, can you clean the pressure sensor with MAF cleaner as well? If not, just carb cleaner? Or not to bother?

 

Also, if you unplug them (with the engine off...) do you have to reset any codes afterwards? I still don't have a OBD2 working yet, and will probably clean them attached if there is a risk of that. Thanks!

 

If you have the special tool bit you can unscrew the maf sensor alone and pull out spray clean and refit. Unplugging with ignition off will not set any new codes. 

The MAP sensor yes can be cleaned with carb cleaner. 

Remember do not rub wipe scrub any sensors, only spray then let evaporate and repeat. 

I used electrical contact solvent cleaner but the proper MAF cleaner is probably better. 

 

Try and let the spray run out and not ingress into the sensors housing and other areas which may not like it. 

 

Picture is what your going to see maf removed, just right of my thumb is the slot where the air passes the metal heated plate spray through there and it should be shiny and like mirror clean. 

The diode to the left of my thumb, also can spray clean no probs. 

 

[Zakowsky]

Finally found a set of pentalobe security drivers with a TD25 in town and started on this. I was thinking these questions were kind of lame, but in case others search in the future thought it might be helpful for somebody. So my problem now is to get the drivers side MAF out without breaking anything. Although I can get to the screw holding the MAF in with extensions, kind of, this would be a lot easier if I could remove the air flow tube. Problem is I don’t want to torque on the housing, because the flex pipe that attaches it to the turbo underneath seems quite flimsy and the housing is really seized in there. But if you do separate them, is the arrow where they come apart?

 

Second point is to get to the pentalobe screws holding the MAF in, it would be much easier to disconnect this line (arrow)

 

This I assume (without a manual) is the upper rad hose - can I disconnect this when the engine is cool without draining some coolant out first? Or will it gush?

 

A bit of an aside, with all this open I can see I do have an oil leak from somewhere under this area. Plus I think there is something else sub-optimal here; as I get used to the engine, I’m realizing I get better acceleration if I short shift it, due to the boost dropping off early. It peaks at maybe 4500 rpm, but then drops off fast after that. Will work on it more tomorrow. Cheers.

 

 

[ekstroemtj]

I did the same many many times in the last weeks. And yes if you are using to

much force you can brake the hose where the flex part is starting.  Best way you take one hand one the part which is flexible and orher hand to the part where MAF is sitting. You need to wiggle a bit and it will go apart. You can use a bit of WD40 on the place where the hose clamp is. Makes it more easy. 

[Zakowsky]

Thanks - so is it supposed to separate at the seam under the clamp? I used WD40 and tried for an hour to pull these apart and they won’t budge. I’m not used to working with plastic parts like this....trying to pry it apart and just gouging things up. 

[lewisweller]

50 minutes ago, Zakowsky said:

Thanks - so is it supposed to separate at the seam under the clamp? I used WD40 and tried for an hour to pull these apart and they won’t budge. I’m not used to working with plastic parts like this....trying to pry it apart and just gouging things up. 

Removing the top hose is not worth it, trust me.

This might help you visualise what the maf is connected to. 

It is a tight fit even with the clamp loose, to get it out rock it side to side whilst hold the lower flexi pipe ribs. As long as you don't rip the lower pipe up, so holding it tight you can wiggle and curse the maf out of the housing. 

When you refit maybe a small wipe of silicon grease on the pipe inner contact point will serve you better for the next time.  

[ekstroemtj]

On your picture you marked it with a red arrow. Thats the place where its seperated. You can use a bit force. Important you gran one hand where the MAF is and your other hand directly where the clamp is sitting. Wiggle.  On your picture its already open a bit. Maybe stick it together and try again. 

[Zakowsky]

Excellent - thanks guys. Working on it now...

[Zakowsky]

Failed...I don’t know what was up with the last people that worked on this vehicle. You mentioned it looked part way out already, but I haven’t moved it in the least. I think they couldn’t get it back together all the way and just forced it on the best they could. I have seen that theme with other work that was done on this e.g. all the plastic that was cracked and broken under the headliner that I saw when I did the hatch shocks.

I think my only option is to remove it from the turbo end and get it onto a workbench. At least that should be plastic on steel.