MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: f00glee on July 17, 2017, 10:45:32 pm

Title: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 17, 2017, 10:45:32 pm
As the subject suggests, been R-tech stage 1 for around 500 miles and seem to have developed a boost leak. The car at full chat now feels as it did before the remap, though perhaps a bit more sluggish to react to the throttle than ever before. Logged the car with VCDS and a friend this evening and the expected vs actual boost levels seem to confirm a boosting issue. A general code scan threw no related errors, only an engine over-speed and ECU comms error noted, but these existed as a result of the remap and before this issue occurred.

At full load the requested boost sits at 21.5psi and tails down to 17.5psi across the rev range of 2000-6000rpm on WOT in 3rd gear. The actual achieved boost lags significantly behind the requested, only achieving 15psi at around 3600rpm, tailing of parallel to the requested boost trace with only 10psi being achieved by 6000 rpm. This was performed in map 5 (full beans).

I repeated the exercise after switching back to map 1 (stock) and interestingly the requested boost remains at the same levels but achieved boost is reduced to a peak of only 6.5psi, tailing off to 3.5psi. The N75 activity between maps 1 and 5 seems to account for this with increased N75 duty cycle in map 5. I guess this is how the variable mapping is achieved, by leaving requested boost alone and manipulating the N75 valve to control impeller speed?

In any case, I'm going to crawl under the car at the next opportunity. My suspected culprits and plan of action are:
1)Remove/inspect DV - even though this is only 3-4k miles old, it could have torn already? Currently a rev G but the rev C which it replaced was actually okay when taken out so this can be put back in temporarily if it is the DV at fault.
2)Inspect piping - focus on couplings at the intercooler, I hear this is a common area for leaks.
3)PCV - look up and try method for testing. Blowing into it or something of the like?
4)General inspection of other charge air system hoses etc.
5)If nothing found at this point, CRY!

If anyone else has had similar symptoms and experience with tracing this kind of issue in the past, I'd be glad to hear any advice you might have. My suspicions are formed only from an hour or two researching on various forums etc. If any more data might be useful, I'm happy to provide Dropbox links to the excel sheets containing the data. Car is an '06 GTI with 34k, noted to be in superb condition by the guys at R-Tech and was fully serviced and prepared for the mapping with pre-emptive replacement of the usual failing points (DV, PVC, timing chain).

This on top of a niggling sluggish cold start (fuel system priming/battery perhaps??) give me a couple of things to get sorted out  :fighting:

p.s. if i have any terminology muddled here please feel free to point this out. I'm relatively new to trying to understand my car more fully and so may be ignorant to any wrong statements I have made.



Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: colesey on July 18, 2017, 06:10:11 am
I would refer this one to Niki Gower since he has worked in it so recently.

Since your actual boost is so much lower than requested, you appear to have a boost leak and I suspect the rubber diaphram of the diverter valve has torn. Mine did soon after Revo Stage 1 and was replaced with a Rev D. I have since replaced this with a GFB DV+ and the car feels stronger and more responsive, so would recommend spending the extra.
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: Dan_FR on July 18, 2017, 10:28:38 am
Inspect DV first. I managed to split one inside two months and less than 1k miles, which drove me in to buying a DV+...

If you suspect a pipe leak, check your fuel trims as any leak post map should mean positive fuel trims.

K03 GTI? Not unheard of for them to have actuator issues, actuator is known for going weak
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 18, 2017, 01:58:10 pm
Inspect DV first. I managed to split one inside two months and less than 1k miles, which drove me in to buying a DV+...

If you suspect a pipe leak, check your fuel trims as any leak post map should mean positive fuel trims.

K03 GTI? Not unheard of for them to have actuator issues, actuator is known for going weak

Thank you both for the replies.

Dan - thank you for the advice on fuel trims, another thing to try and log should the problem not be obvious. Yes k03.

As for the actuator comment, are you referring to the N75? If so, again something to look into with an open mind. Though as I was able to log the boost across two different maps, where two vastly different recorded N75 duty cycles produced differing actual boost pressures, my assumption is that this shows some activity from this valve/actuator making a difference and so shouldn't be the problem?

The comments are greatly appreciated and I'll be sure to post up the outcome. May not get a chance to have a proper look until Saturday. Really hoping it is as simple as the dv!




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Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: Dan_FR on July 18, 2017, 09:23:06 pm
The actuator is the bit that actually opens and closes the wastegate using boost pressure, the N75 is just the electronic valve that controls this by regulating the boost pressure supplied to the actuator.

I suspect it'll be the DV. If it is, get a DV+ fitted. Its a must have item on a K03 where the DV is such an awkward bugger to get to. Fit and forget solution
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: r5gtt on July 18, 2017, 10:39:17 pm
Oem dv internal

 (https://image.ibb.co/eEDAea/IMG_0531.jpg)

GFB DV+ Very much recommended by me

(https://image.ibb.co/iFybKa/IMG_0533.jpg)

Easiest to get to when removing drivers arch liner

(https://image.ibb.co/dT6z5F/IMG_0532.jpg)
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 19, 2017, 08:18:59 pm
Spent a couple of hours under the car and found a perfectly intact DV and what seemed like a slightly misplaced intercooler connection on the hot air side. Removed, cleaned and re assembled all to give it the best chance of making some kind of difference.

...got exactly the same boost log results as my first tests the other day.

Didn't get round to checking the PCV as I've given up for today (though the more I read the less likely this seems - no rough idle being experienced, for example. Looking at what little else of the turbo piping I could see from under the car, there was nothing glaringly obvious, maybe a little weeping down the side of the intercoolers plactis end tank but hard to see. Maybe a crack in the inter cooler isn't out of the question. Looks like I need to find somewhere local who can do a smoke test or make the trip back to R-tech for some diagnostics.

 :sad1:

Thanks for the info @r5gtt (http://www.mk5golfgti.co.uk/forum/index.php?action=profile;u=11199). If it had been the dv or if this one splits in the future ill be sure to upgrade to one of those.
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 21, 2017, 10:21:39 am
Update. Had a look at some other potential culprits. PCV valve seems fine as I can feel the valve close if I try to blow into the valve from the intake connection. Also tried running the car with the MAF sensor unplugged as I had read reports of a dirty/faulty MAF giving incorrect readings could trick the ECU into requesting different boost levels. This also made no difference.

Looks like I'm still heading down the path of a leak I cannot see or a problem with a component which isn't accessible on the driveway (actuator/the turbo itself).

Called R-tech yesterday but as Niki is away I was asked to call back on Monday. Hoped to have this sorted within a few days but looks like I'll have to be patient for a few more to get further advice. May end up going to R-tech for diagnosis.

Fingered crossed it's still just a leak I cannot see without smoke testing. Will keep updating as I learn more!


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Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 21, 2017, 10:33:46 am
P.s. Would anyone know of a place which can offer smoke testing for the detection of boost leaks in the cambridge area?


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Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: Dan_FR on July 21, 2017, 12:23:35 pm
Did you check the fuel trims (block 032 - don't clear fault codes) to see if you have a high positive number? That would be a good indication of a leak. When you have logged boost, have you logged N75 DC too? Also checked Lambda correction (block 001) on a run to check it is is staying within the 25% that the ECU can adjust for?

The more logs you can do and share with us, the more chance we have of helping.... Use APRs logging guide for advice on what to log: http://www.goapr.co.uk/support/datalogging.php

I do suspect its either a leak or an actuator issue though from what I've read so far.

As for a recommendation, I'd suggest heading over to AKS Tuning. They're not too far from you and would no doubt get to the bottom of the issue
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 21, 2017, 01:24:22 pm
@Dan_FR (http://www.mk5golfgti.co.uk/forum/index.php?action=profile;u=9513) I believe I do have some logs showing what you mention, except for lambda correction. 2 links here. Some parameters change as I was attempting to reduce measured values to increase sample rate of the tool. One is with MAF plugged in, 1 out. This was last night testing to se if this made any difference. The answer was none whatsoever as far as i can tell. Perhaps suggesting the MAF readings are really rather close to the default expected values for air in.

Fuel trims both seem to be negative if I've logged the correct block 32 values. Does this make sense? Less air due to lower boost = less fuel to avoid running lean? Or am I looking at this wrong?

I took a look at the "what to log" section of APRs site before going out last night and tried to include some of the more commonly occurring parameters.

Links:
https://www.dropbox.com/s/gz3mp2vq2oo3ggb/3rd%20pull%20maf%20in%20leak%2020-07.xlsx?dl=
https://www.dropbox.com/s/2d56eozr2zn7ujr/3rd%20pull%20maf%20out%20leak%2020-07.xlsx?dl=0

Can run another log with a specific set of up to 12 parameters if it would be useful. Or fuel trims again with the MAF in, as the log which includes block 32 had the MAF out. Though I'm sure these values don't seem to change in real time?

Ill bear AKS in mind as an option should I need them. Thanks for the input!  :happy2:


Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: pudding on July 21, 2017, 01:56:49 pm
@Dan_FR (http://www.mk5golfgti.co.uk/forum/index.php?action=profile;u=9513) I believe I do have some logs showing what you mention, except for lambda correction. 2 links here. Some parameters change as I was attempting to reduce measured values to increase sample rate of the tool. One is with MAF plugged in, 1 out. This was last night testing to se if this made any difference. The answer was none whatsoever as far as i can tell. Perhaps suggesting the MAF readings are really rather close to the default expected values for air in.

Fuel trims both seem to be negative if I've logged the correct block 32 values. Does this make sense? Less air due to lower boost = less fuel to avoid running lean? Or am I looking at this wrong?

I took a look at the "what to log" section of APRs site before going out last night and tried to include some of the more commonly occurring parameters.

Links:
https://www.dropbox.com/s/gz3mp2vq2oo3ggb/3rd%20pull%20maf%20in%20leak%2020-07.xlsx?dl=
https://www.dropbox.com/s/2d56eozr2zn7ujr/3rd%20pull%20maf%20out%20leak%2020-07.xlsx?dl=0

Can run another log with a specific set of up to 12 parameters if it would be useful. Or fuel trims again with the MAF in, as the log which includes block 32 had the MAF out. Though I'm sure these values don't seem to change in real time?

Ill bear AKS in mind as an option should I need them. Thanks for the input!  :happy2:

What OBD lead have you got, and are you using the full licensed VCDS, or the freebie version with an ebay lead?   If you have a proper Ross-Tech HEX+CAN lead, you can switch on "Turbo!", which increases sample rate from about 3 per second, to 30.  I use that all the time as the lambda refresh rate, for example, is way too slow otherwise.   I'm not sure if Turbo mode works with clone leads, but worth a go.

As you're never hitting the boost target, it's got to be something fundamental.  Split DV probably.  They don't always cause rough running at idle, unless it has a massive gash in it.  A pin hole tear is enough to bleed off boost.
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 21, 2017, 02:36:17 pm
@Dan_FR (http://www.mk5golfgti.co.uk/forum/index.php?action=profile;u=9513) The turbo button does make a difference for me but only increases the refresh rate from ~1/s to ~3/s if measuring lots of things all at once. Not exactly sure on the flavor of cable, was off ebay and not one of the newest types I believe. I saw on APRs site there is some other setting in the communications setup which can increase refresh rate. Next time I do some logging ill look that up. Not so sure I didn't fiddle around with these values before so may have made things worse rather than better!  :signLOL:

I assume your reply means you don't reckon there is anything wrong with the numbers in the logs (other than boost of course)? Ill be annoyed at myself if it does turn out to be the DV. I did give it a really good looking over for a few minutes and couldn't see any tears at all. There was a tiny amount of fraying on the underside of the diaphragm where it is bonded to the metallic part, but i gave it a good pull around and was happy that it was only superficial.

I had the choice of putting the revG back in (which I did) or putting in an old revC I had which came out as a preventative measure and was otherwise OK. Maybe its worth chucking the revC in and see what happens. Was a right faff getting it off to check the other day - didn't seem to have the right combination of ratchets/extensions for easy access. Plus, the revC will have to come out again anyway, either to put the G in again if no different or for a dv+! eurgh!  :fighting:


Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: pudding on July 21, 2017, 04:02:04 pm
@Dan_FR (http://www.mk5golfgti.co.uk/forum/index.php?action=profile;u=9513) The turbo button does make a difference for me but only increases the refresh rate from ~1/s to ~3/s if measuring lots of things all at once. Not exactly sure on the flavor of cable, was off ebay and not one of the newest types I believe. I saw on APRs site there is some other setting in the communications setup which can increase refresh rate. Next time I do some logging ill look that up. Not so sure I didn't fiddle around with these values before so may have made things worse rather than better!  :signLOL:

I assume your reply means you don't reckon there is anything wrong with the numbers in the logs (other than boost of course)? Ill be annoyed at myself if it does turn out to be the DV. I did give it a really good looking over for a few minutes and couldn't see any tears at all. There was a tiny amount of fraying on the underside of the diaphragm where it is bonded to the metallic part, but i gave it a good pull around and was happy that it was only superficial.

I had the choice of putting the revG back in (which I did) or putting in an old revC I had which came out as a preventative measure and was otherwise OK. Maybe its worth chucking the revC in and see what happens. Was a right faff getting it off to check the other day - didn't seem to have the right combination of ratchets/extensions for easy access. Plus, the revC will have to come out again anyway, either to put the G in again if no different or for a dv+! eurgh!  :fighting:

I haven't looked at the logs, I don't have access to dropbox at work.

Ah OK, I'm sure I read further back that you hadn't checked the DV yet, but sounds like it's OK then.

If all the hardware checks out, you'll need to arrange an appointment with Dr Nikki for another checkup!
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 21, 2017, 04:23:04 pm
Sorry @Pudding (http://www.mk5golfgti.co.uk/forum/index.php?action=profile;u=10733) I hadn't realized it was you replying, I had assumed it was a continuation of the conversation with Dan. Doh! Thanks for your input in any case :) Think I'm gonna do my best to put it out of my mind for the weekend to avoid chasing my own tail, see what "Dr Nikki" recommends come Monday. Though I am usually the sort of person who cant let this sort of thing lie, even for a minute, ill do my best!

In the mean time, any more ideas from anyone, I'm all ears!
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: pudding on July 21, 2017, 04:31:23 pm
No worries  :smiley:

I hope you get it sorted.  Must be frustrating not getting your full compliment of boost!
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 24, 2017, 01:06:41 pm
Just off the phone with R-Tech and they're saying I need to either drop the car off so they can look at it soon as they get a moment (1.5 hour trip up there then no way to get back home) or book a diagnostic slot at my cost, but this cant be done until late august!

Not sure what to do. If I book the slot Ill be really pi**ed off If I get there and it was something simple that I had missed after all.

I do understand the guys at R-Tech are busy and my problem is unknown so could take a while to diagnose...

Dunno what to go for!



Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: AJP on July 24, 2017, 02:27:33 pm
Just off the phone with R-Tech and they're saying I need to either drop the car off so they can look at it soon as they get a moment (1.5 hour trip up there then no way to get back home) or book a diagnostic slot at my cost, but this cant be done until late august!

Not sure what to do. If I book the slot Ill be really pi**ed off If I get there and it was something simple that I had missed after all.

I do understand the guys at R-Tech are busy and my problem is unknown so could take a while to diagnose...

Dunno what to go for!
Why not see if you can get it booked in at AKS a bit sooner? They're one of the best regarded VAG specialists in the country.
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 24, 2017, 02:41:18 pm
Just off the phone with R-Tech and they're saying I need to either drop the car off so they can look at it soon as they get a moment (1.5 hour trip up there then no way to get back home) or book a diagnostic slot at my cost, but this cant be done until late august!

Not sure what to do. If I book the slot Ill be really pi**ed off If I get there and it was something simple that I had missed after all.

I do understand the guys at R-Tech are busy and my problem is unknown so could take a while to diagnose...

Dunno what to go for!
Why not see if you can get it booked in at AKS a bit sooner? They're one of the best regarded VAG specialists in the country.

Did give them a call at lunch time - they're fully booked until September!

I think I'm going to have to go over some of the checks I had made previously to be as sure as I can about what I've looked at. At which point, if all still looks okay as far as I can see, I'll have to book in to R-Tech.




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Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: AJP on July 24, 2017, 02:46:10 pm
Just off the phone with R-Tech and they're saying I need to either drop the car off so they can look at it soon as they get a moment (1.5 hour trip up there then no way to get back home) or book a diagnostic slot at my cost, but this cant be done until late august!

Not sure what to do. If I book the slot Ill be really pi**ed off If I get there and it was something simple that I had missed after all.

I do understand the guys at R-Tech are busy and my problem is unknown so could take a while to diagnose...

Dunno what to go for!
Why not see if you can get it booked in at AKS a bit sooner? They're one of the best regarded VAG specialists in the country.

Did give them a call at lunch time - they're fully booked until September!

I think I'm going to have to go over some of the checks I had made previously to be as sure as I can about what I've looked at. At which point, if all still looks okay as far as I can see, I'll have to book in to R-Tech.




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Dang. That is usually the case with the top specialists, unfortunately. Statller, R-Tech, AKS etc, a 5 week wait at least seems the norm.

There must be somewhere competent close by who can get you in sooner. The guys above are the ones you hear/read about the most, but that doesn't mean there aren't alternatives out there.

I'd be hitting Google like a machine if I was you. Waiting weeks for R-Tech would do my head in a bit.
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 24, 2017, 03:05:25 pm
Just off the phone with R-Tech and they're saying I need to either drop the car off so they can look at it soon as they get a moment (1.5 hour trip up there then no way to get back home) or book a diagnostic slot at my cost, but this cant be done until late august!

Not sure what to do. If I book the slot Ill be really pi**ed off If I get there and it was something simple that I had missed after all.

I do understand the guys at R-Tech are busy and my problem is unknown so could take a while to diagnose...

Dunno what to go for!
Why not see if you can get it booked in at AKS a bit sooner? They're one of the best regarded VAG specialists in the country.

Did give them a call at lunch time - they're fully booked until September!

I think I'm going to have to go over some of the checks I had made previously to be as sure as I can about what I've looked at. At which point, if all still looks okay as far as I can see, I'll have to book in to R-Tech.




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Dang. That is usually the case with the top specialists, unfortunately. Statller, R-Tech, AKS etc, a 5 week wait at least seems the norm.

There must be somewhere competent close by who can get you in sooner. The guys above are the ones you hear/read about the most, but that doesn't mean there aren't alternatives out there.

I'd be hitting Google like a machine if I was you. Waiting weeks for R-Tech would do my head in a bit.

This whole thing is doing me head in!

Trying to take a pragmatic approach and stay calm! You're right, someone closer may be able to do something. I really just want someone who is able to pressurise the charge air circuit so any leaks can be hunted down.

As a last ditch effort I'm gonna chuck in a pristine rev c diverter I have lying around. Just in case my current rev g is damaged in a way which wasn't obvious. After that I'll consider my next steps.

Can see this leading toward money and time to get somewhere who can do a smoke test just to find out e.g. My intercooler is damaged or something. But if that's what I need to do, it's got to be done! And if it had to be R-Tech or similar, so be it!


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Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: AJP on July 24, 2017, 03:51:55 pm
Just off the phone with R-Tech and they're saying I need to either drop the car off so they can look at it soon as they get a moment (1.5 hour trip up there then no way to get back home) or book a diagnostic slot at my cost, but this cant be done until late august!

Not sure what to do. If I book the slot Ill be really pi**ed off If I get there and it was something simple that I had missed after all.

I do understand the guys at R-Tech are busy and my problem is unknown so could take a while to diagnose...

Dunno what to go for!
Why not see if you can get it booked in at AKS a bit sooner? They're one of the best regarded VAG specialists in the country.

Did give them a call at lunch time - they're fully booked until September!

I think I'm going to have to go over some of the checks I had made previously to be as sure as I can about what I've looked at. At which point, if all still looks okay as far as I can see, I'll have to book in to R-Tech.




Sent from my iPhone using Tapatalk
Dang. That is usually the case with the top specialists, unfortunately. Statller, R-Tech, AKS etc, a 5 week wait at least seems the norm.

There must be somewhere competent close by who can get you in sooner. The guys above are the ones you hear/read about the most, but that doesn't mean there aren't alternatives out there.

I'd be hitting Google like a machine if I was you. Waiting weeks for R-Tech would do my head in a bit.

This whole thing is doing me head in!

Trying to take a pragmatic approach and stay calm! You're right, someone closer may be able to do something. I really just want someone who is able to pressurise the charge air circuit so any leaks can be hunted down.

As a last ditch effort I'm gonna chuck in a pristine rev c diverter I have lying around. Just in case my current rev g is damaged in a way which wasn't obvious. After that I'll consider my next steps.

Can see this leading toward money and time to get somewhere who can do a smoke test just to find out e.g. My intercooler is damaged or something. But if that's what I need to do, it's got to be done! And if it had to be R-Tech or similar, so be it!


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AFAIK a DV can indeed be leaky without being visibly faulty. It's worth a go, and won't cost you money to try. Just time and the usual fannying about under the arch! I've also read a thread or two regarding the DV not being fully 'home' when fitted, and exhibiting the usual boost leak symptoms, so that's another thing to check when you put the Rev C in.

I'm sure I've heard of another place in Cambridgeshire that does a bit of VAG stuff amoungst other things. I'll have a look...
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: AJP on July 24, 2017, 03:56:35 pm
These guys:

http://www.cjlraceengineering.com/

And taken from the Yell listing:

"Although we cater for all makes and models, we specialise in V.A.G chassis and engine platforms including the popular 1.8 Turbo and 2.0 TFSI applications and also all Caterham road and race applications."

Might be worth a call / email.
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: pudding on July 24, 2017, 03:57:50 pm
You could try Stealth Racing in Southam.  Probably busy as well, but maybe not no appointments until September busy!

You could perhaps buy a DV+ and never have to go in there again.  £90ish isn't expensive for fit and forget imo.  If it doesn't solve it, at least that's one area of investigation you don't have pay someone £50-60 per hour to look over again.
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 24, 2017, 04:13:14 pm
@AJP (http://www.mk5golfgti.co.uk/forum/index.php?action=profile;u=11926) Ill report back, hopefully tomorrow, if I get a chance to make the swap back to the old dv tonight.

Googling for "boost leak test cambridge" or similar reveals no obvious results. I think this in itself is quite strange, considering the number of cars going about with turbochargers fitted these days. A couple of garages I have spoken to say they manage to find leaks without any way of pressurising the system. I mean, I can understand If a leak is obvious (e.g. a pipe dropped off) then this is the case, but who's to say any given charge air system couldn't have hard-to-see leaks affecting performance (maybe like I am experiencing, or even to a lesser degree). Would have thought some system to test for this would be bread and butter these days.

Thanks for the recommendations, I'll bear them in mind.

@Pudding (http://www.mk5golfgti.co.uk/forum/index.php?action=profile;u=10733) the dv+ will be the way I go if it does in fact turn out to be the culprit. I have old boost logs from just before the revC came out showing It was fine before preemptive replacement, If boost is fine after going back in, ill leave it that way til I can get a dv+. If it still makes no difference, the revG will be going back in before seeking professional assistance(for both the car and my mental state, at this rate..)!  :rolleye:

Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: pudding on July 24, 2017, 04:37:55 pm
Google Scotty Kilmer cigar smoke test  :grin:

Seriously.....he blew cigar smoke into an engine on one of his youtube clips!   There are a number of DIY smoke tester ideas that cost peanuts to make.  Might be worth a shot?
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 25, 2017, 11:44:06 am
The old (immaculate) revC dv made no difference. One thing I can say is that over the 8 or 10 logs I've made in the last 10 days my results are always very consistent. Requested and achieved boost levels are always the same give or take a few hundred RPMs and 0.5PSI. At least I haven't made anything worse  :signLOL:

I've decided to stop with the DIY diagnosis and I'll be letting R-Tech have the car for a proper look. Means I'll be car-less until they get a chance to look it over and its a bit of a pain getting it there but in the end I've decided that it needs doing, so that's the way its got to be. I appreciate the ideas people have given that I didn't try (e.g. DIY smoke test), ultimately decided I've spent an awful lot of time hunting for the problem so far, so to avoid more wasted time and potential mis-diagnosis, its time for the professional to step in.

Will update with findings soon as I have them. Thanks for all of your help so far. 
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: ghuk on July 25, 2017, 01:28:30 pm
Hi bud

I too tried phoning AKS a few times recently as they were recommended by quite a few people on this forum, however they were talking 5-6 weeks before they could even look at my Golf GTI.

I therefore searched around as I unfortunately couldn't wait that long and found a company called Vagtech in Milton Keynes. I know its a bit of a distance from Cambridge but they do have courtesy cars which might help the cause

Anyway just an idea  :happy2:

 
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 25, 2017, 09:28:18 pm
Update!

R-Tech are looking into the issue. They went over the car earlier.

They checked all the usual suspects and didn't find anything (phew - I didn't miss something silly!) Pressure test showed no leaks at all. System held 20psi quite comfortably. The thinking now is that its either the N75 valve or even potentially could be the catalytic converter has become clogged (possibly as a result of my pre cat removal).

Should hear the diagnosis in the next few days. I may possibly need to source an OEM downpipe to get to R-tech at some point soon. Anyone got one going spare?
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: pudding on July 26, 2017, 09:23:32 am
Give BCS a call, they've probably got loads of OEM downpipes!

When you gutted your precat out, did you do it facing the floor so that none of the 'crumbs' fell back into the downpipe?   That's the only way the main cat would get blocked really.

N75 should fault code I would have thought? Underboost errors etc.
Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on July 26, 2017, 09:52:26 am
Give BCS a call, they've probably got loads of OEM downpipes!

When you gutted your precat out, did you do it facing the floor so that none of the 'crumbs' fell back into the downpipe?   That's the only way the main cat would get blocked really.

N75 should fault code I would have thought? Underboost errors etc.

Pre cat was done by my usual garage. They had never done one before so I explained that it needed to be insured that none of the material fell further into the exhaust, they seemed perfectly happy with this and appeared to be comfortable. Sticking my head round the corner from time to time they appeared to be doing all the right things. Still, may not be this after all.

Do you think BCS would be interested in supplying me with an old downpipe? The thought crossed my mind but I though that could be a bit cheeky, as they are in the business of selling replacements for that very component. They'd rather sell me one of their downpipes I'm sure! Still, a maybe - can't hurt to ask!

As for N75, niki said his maps work on a fixed N75 duty cycle set, presumably from a load/rpm lookup table. Though the N75 may be perfectly fine, the pressure regulator and then the mechanical linkage and waste gate further down the line, may have an issue. If it is a mechanical issue, there may not be a sensor which could pick it up. I.e the valve itself may be doing what it should be but the pieces of metal it drives could be faulty.

Time will tell! Definitely learning more about the car as a result if all of this.


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Title: Re: Stage 1 for 500 miles - Boost Leak? - Advice Please!
Post by: f00glee on August 07, 2017, 09:02:42 pm
So I think the guys at R-Tech have sorted my car. They reckon when they took the downpipe off a load of s**t fell out, pointing towards my pre cat removal not having been done as well as it could have been. The place I used to remove it said they had never done one before and though I explained the importance of making sure it was a clean removal it seems there was enough debris left to cog the main cat and give me the performance issues I was seeing.

Live and learn! So glad it's sorted!


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