no signs of improvement... the car continues to disappoint in performance

summing it up:

- replaced breather pipes

- pressure tested the whole intake system and got rid of all the leaks

- verified DV membrane

- bypassed N249, cleaned it, then deleted the bypass

- verified N75 (mechanical and electrical)

- cleaned actuator rod with "crawling" rost off and degrip solution

fact is:

- turbo spools up around ~1800 rpm

- ecu has no recorded fault codes

- not a single trace of turbo smoke

- i've gone through all the intake system (minus actuator and wastegate); everything i checked was or is now working properly

- my china-vagcom-cable went trash, so nothing to record my boost values with

i'll buy a boost gauge tomorrow (if i can sort one that quick) to log my boost values

question:

is it ok to try and move the actuator rod by hand ?

Edited 3 February, 201214 yr by za_killer

If you can get your hands down the back of the engine it's ok to move the rod, just don't adjust the nut on it as that can cause it to overboost. The rod should be attached to a lever at the turbo end which is connected to the wastegate flap inside the turbo so I would apply some spray to the lever and check that it's moving smoothly when you move the rod then at least you know the wastegate is closing and opening as it should.

If you get a boost gauge that will tell you what the actual boost is but it would be helpful to have VAG-Com to check actual vs. requested. Maybe post in the VCDS area of the forums and see if there is anyone near you that will come and do it? On the boost gauge you're looking for peak boost of about 10psi if it's standard.

At least with a boost gauge you could rule out the turbo as being the reason why the car feels flat.

Are you the first owner... and sure the car hasn't been remapped? Could be a fault with the map if it has been. Or if it was remapped by a previous owner and you didn't know about it then the standard map could have been put back on if it's been into a main dealer for work... That will make it feel a lot flatter compared to what it would be like remapped.

Did you have any fault codes cleared after you replaced the CTS and fixed the split pipe? The codes need to be cleared after the work is done or the ECU thinks there's still a fault and won't run right.

a major snowstorm is putting my work on hold now...

i tried moving the rod this morning (stone cold engine, -7 outside temp). wouldn't move a single mm... i applied reasonable force (being careful enough not to overdo it) in either directions but still nothing. does this point to a stuck actuator or rather a wastegate issue ?

i'm not the first owner.

all the work carried out at the main dealer was a belt + kit change, plus a minor thing related to the climatronic. nevertheless my problems started about a month and a half after my last service visit.

code related to CTS was the only one shoving. cleared it myself. no other codes since then (double checked 3 days ago - my china-vagcom-cable still enables me to read and erase codes, but that's the only thing i can now do with it, as the communication with the ECU is very unstable on the cable side)

i'll pause my actions for 2 days (forecast tells me that's when it'll stop snowing), till then i'll gather all the info and opinions out there to try and sort it the moment the sky clears.

You could try (with the engine off) applying air pressure to the hose between the N75 and actuator and see if that moves the lever to close the wastegate. Possibly doing it by hand isn't enough.

There's a vid of it here on a K03S turbo although off the car:

insane winter and snow conditions here.

nevertheless, got my hand on a new air compressor and shortly tested my actuator

opened around ~6 psi, was fully open at ~10.

it slams shut as it should (rapidly).

will do a longer test tomorrow, as well as repeat the leak test (and see actual values on the pressurized system).

boost log or test run (rolling) is impossible due to weather conditions...

Its starting to sound more and more like it's nothing to do with the turbo but you'll only know that for sure if you get Vag-Com on it and read the actual and requested boost values.

Just been reading this thread and want to add a bit to it.

You can pull the actuator by hand, it's held shut with a calibrated spring so will be fairly hard to move, but it shouldn't feel stiff. Also, the turbo won't produce any boost at all without the engine being under load (i.e. driving) - That is why you had a vacuum on the dv line when holding it at 3000 rpm.

The N75 runs on PWM, so turns on and off really fast (10+ times per second). That way, it can open the wastegate gradually, rather than all or nothing. You can test them with a 12v supply, and it will open, but it still might be past it. Mine was on the original n75 (8 years old), and it was slow at responding due to the rubber components inside deteriorating, causing an over/underboost loop.

Whereabouts are you? I have working vagcom and a brand new n75 you could borrow.

Its starting to sound more and more like it's nothing to do with the turbo but you'll only know that for sure if you get Vag-Com on it and read the actual and requested boost values.

getting my cable fixed these days. hoping the weather will be mercyfull, so i'll have enough runway to do the log.

Just been reading this thread and want to add a bit to it.

You can pull the actuator by hand, it's held shut with a calibrated spring so will be fairly hard to move, but it shouldn't feel stiff. Also, the turbo won't produce any boost at all without the engine being under load (i.e. driving) - That is why you had a vacuum on the dv line when holding it at 3000 rpm.

The N75 runs on PWM, so turns on and off really fast (10+ times per second). That way, it can open the wastegate gradually, rather than all or nothing. You can test them with a 12v supply, and it will open, but it still might be past it. Mine was on the original n75 (8 years old), and it was slow at responding due to the rubber components inside deteriorating, causing an over/underboost loop.

Whereabouts are you? I have working vagcom and a brand new n75 you could borrow.

thanks for the input and for your help. unfortunately i'm as far as 2k km away from GB, somewhere in SE europe (Romania)... :(

actuator works fine, but my attempt to repeat the boost leak test failed. used a audi 12v tire compressor; pressure kept climbing steady towards 10 psi (climbed slower above this value) as the compressor was turned on, but the moment i turned it off the needle in the gauge dropped instantly to 0 with not even a sound...

i should say that i always turned the compressor off at max 15 psi.

found a vid and some forum examples of stuck/blown wastegate arms. anybody seen something like this ?

Edited 7 February, 201214 yr by za_killer

finally got my china cable repaired...

2 runs, 3rd gear (sorry, missed the time to isolate the values, so graphs show 1st and 2nd gear also)

is the ~2 sec delay normal (requested to actual pressure) ?

first run:

second run (first graph showing: pressure (incl. atm pressure) = f (rpm); second one showing: pressure (minus atm pressure) = f (rpm))

Edited 21 April, 201214 yr by za_killer

VCDS screenshot

red - RPM

green - engine load

yellow - requested charge pressure

purple-ish - actual charge pressure

It's usual for the actual boost to take a little while to catch up to the requested boost and the graphs show the actual follows the requested quite well so doesn't look like a boost leak problem. The peak and hold boost is about what i'd expect for a standard car. Was it remapped in the past? Has it been in anywhere that might have taken the map off?

i have absolutely no clue if the car has been remapped (and taken off) before i bought it. it certainly wasn't removed (the map) during my ownership, as i was present on every occasion the diagnostic cable was hoked up in the dealers garage... (climatronic diagnostics and repair, and coil-pack recall) - i've done everything else myself...

the graphs do look promising to me too, and i do rule out a boost leak.

forgot to mention the absence of fault codes

nevertheless i'm still not pleased with the performance of the car... and it feels like it's gradually getting worse (may be just my imagination) as the miles pile up...

i've moved on, considering the exhaust system (a clogged cat) now...

ps: about a week ago i asked a friend to watch my exhaust as i took off in 1st gear: idle to rpm limiter. he reported minor (but constant) amounts of black smoke for as long as i held the foot on the pedal. that might point towards some over-fueling...

Edited 21 April, 201214 yr by za_killer

thinking about backpressure testing, so i've got 3 things in mind:

1. pressure gauge in pre-cat o2 sensor (should keep steady at constant rpm)

2. vacuum gauge measuring intake manifold absolute pressure (should read constant values whilst engine is reved 2k~2.5k rpm in neutral)

3. vag-com log of actual boost pressure (considering the atmospheric pressure, and basically applying method 2)

will the 3rd method listed suffice or will it not be precise enough.

in the meantime: plug change scheduled next week

Edited 22 April, 201214 yr by za_killer

managed to do a log with vag-com of the actual charge pressure in neutral.

pressure values were constant at idle and 2500 rpm (990 mbar). reving the car up to 2800 rpm did make the value rise to 10000 mbar.

this would point to a "healthy" backpressure and healthy cat.

my flex pipe is on it's way out (seen exhaust gases escaping through the mesh) so i'm tempted to think the clogged cat and the decomposed flex cancel each other out in terms of backpressure...

err having it in neutral won't prove owt lol.

You'll have to be moving to get the turbo to work

Can you do a VCDS log of the MAF values against revs and post the results on here? (log block 003)

Ideally you need to do it in 4th gear and start around 2k revs then take it to the redline (disclaimer: you will need a good half a mile of straight private road for this )

I can roughly work out your horsepower and torque figures from that, should give you an idea if the car is running as it should be.

err having it in neutral won't prove owt lol.

You'll have to be moving to get the turbo to work

was done according to some guides i've read round the net, and only for backpressure testing... the idea behind it: if vacuum fades exhaust gases can't make their way out as they should so exhaust (cat) is clogged (more or less),

Can you do a VCDS log of the MAF values against revs and post the results on here? (log block 003)

Ideally you need to do it in 4th gear and start around 2k revs then take it to the redline (disclaimer: you will need a good half a mile of straight private road for this )

I can roughly work out your horsepower and torque figures from that, should give you an idea if the car is running as it should be.

4th gear, 2k to redline, understood

spark plugs are arriving tomorrow morning, will slam them on and do the run

i'll be changing the clutch pedal switch at the same time, as it developed an error code

and again, thank you for your support so far

EDIT: what coefficient would you apply on g/s to calculate the bhp ?

the torque figure would be: lb/ft = (bhp) * 5252 / (rpm) right ?

Edited 24 April, 201214 yr by za_killer

You just need to divide the MAF figures you've logged at each point in the revs by 0.8 to get the BHP at those revs. Quick example:

2000 revs - 50g/s = 62.5bhp

3000 revs - 80g/s = 100.0bhp

4000 revs - 100g/s = 125.0bhp

5000 revs - 120g/s = 150.0bhp

6000 revs - 150g/s = 187.5bhp

*redline*

It's not completely accurate but it's only about 3-4% out. I got 187bhp max on my VRS which was standard. And yep the torque calc you mention is what I would use to get the torque at each point in the revs. Peak torque on a standard car should be 175ft/lb somewhere around 3k revs I think

new NGK plugs, done the run, baffled by the results...

NOTE: was a bit windy today (mostly from the side)

here are the figures:

bhp peak ( air mass(g/s) / 0.8 ) = 173.7875 [hp]

torque peak ( bhp * 5252 / rpm ) = 164.3637 [lb/ft]

torque peak ( (bhp * 5252 / rpm) * 1.35581795 ) = 222.8473 [Nm]

although the values don't seem quite perfect, they would pretty well explain the almost 8 years age of the car

that leaves me with only one conclusion: the car was remaped in the past... i cannot explain myself how the map could have been taken off... no adaptation whatsoever was done to the ecu, only fault code reading and clearing... and the curious thing is, performance went trash despite the car not being hooked up to no tester whatsoever (in a period of over a month)... i'm gathering my thoughts at the moment to decide what to do with it next...

Some of the older trial maps from APR and REVO would only last a certain number of ignition cycles so if the difference between when you bought the car and how it feels now is that massive it might possibly have had a trial remap under the previous owner which has now expired. Depends how much you used the car since you bought it as to whether thats likely.

Certainly if you went from driving a remapped VRS one day to a standard one the next it would be like night and day. If the difference doesn't feel quite that significant then the issue lies somewhere else. You could however spend weeks or months trying to track it down.

Those figures do look a little low for a standard one (even after 8 years they should be close to 180bhp/175ft/lbs) but as they're all based on figures from the MAF, if the MAF is slightly faulty it would distort those figures.

If you went down the road of getting it remapped in future then I would make sure you go somewhere that checks everything (MAF, vac hoses, coils, actuator) before and after the remap that way at least you can be sure its running the best it can.

i use the car on a daily basis, and i thought about trial maps, but 4 months does seem a bit of a long period for a trial software under this conditions...

i incline to think i'm not an idiot and just imagining things so i'm going to get it rolling road-ed to flatten out my last suspicions. will post the outcome

Yeah that is a fair bit of time. IIRC Revo trial maps used to last for 5 or 6 hours of driving and you must have done way more than that!

Let us know how the rolling road goes. If it's a decent place they will check all the pipes and everything as well even though I'm sure you've done all this, it's been a pretty thorough investigation.

just finished the dyno run

the rr guy said the clutch was slipping a bit... not sure if i'm to trust his opinion [nearest one accessible was located at the university]

bhp is a bit off, but at the right rpm, torque does come pretty late...

opinions ? [ ps. the guy said he had to do it a bit "progressive" so the graph would come out right... wtf ? ]

Edited 4 May, 201214 yr by za_killer

Torque is spot on for a standard car at 240NM. 170bhp is pretty low power but does match your VCDS results. I would've expected torque to peak around 1000 revs lower than that but if they've measured things via resistance on the rollers then a slipping clutch might have affected that.

If you're considering a remap then it sounds like the clutch will want sorting before that. Not sure on the low peak bhp figure, I doubt that's down to the clutch as you got a similar figure via VCDS which used the MAF values. I'm not sure what else to suggest if you have checked everything already which I'm sure you have.

I remember the second time I took mine on a dyno it only made 173bhp and that was due to a split in the little vac hose under the manifold but from what I can remember earlier in the thread and previous thread all that has been checked on your car?