APR 2+ boost question

[MedicCarter]

So for the last 3-4 weeks I have noticed a change in my boost pressure via digital VEI gauge in first gear all the other gears boost reading are normal. Up until 3-4 weeks ago a good hard pull would show boost of 18-20 psi but now I can only get 18 psi rarely and my readings are now 3-8 psi. The car doesn't feel like I'm loosing power maybe a little via my by dyno but overall it feels fine. Since the start of the issue I have checked the plugs and they are tan and look good with only 5k on them. I recently changed the air filter I have changed the oil vag com pulls no codes and I have removed the bumper and checked all the FMIC piping losened and re tightened all the clamps and pulled the diverter. Everything was fine no leaks no change with anything I have done so I called APR to see what boost I should be pulling and if the cold weather change could affect the boost. I was told that if I'm not throwing codes for under boost then that's not an issue and that the change in temp and humidity could cause the computer to adapt and pull less boost. I'm a little lost and other than a leak test I think I have hit all the possible problems. I can't see it being a leak since in every other gear I can hit 18 psi the car I don't think it's the turbo I only have 44k on the car it's never been raced the oil is changed every 4,500-5k it rarely ever has any smoke it runs and drives great and idles fine. I have 21-23 on my vacuumed gauge at idle and oil pressure has never been lower than 21-25. Can anyone confirm or deny the change in the boost readings with colder temps in first gear or give me any other ideas hell maybe I'm chasing a ghost.

[CVTwhatadumidea]

I only hit 15 psi with apr 2+ in first gear, but no FMIC

[Hugh@EuropaParts]

I had APR stage 2 with AWE FMIC, 034 HFC, STaSIS Exhaust, and hit 19psi once...

When they say that it's the "safest" tune they aren't lying.

[MedicCarter]

I have always hit 18 with peaks once in awhile at 19 and 20. I'm ok with it being the safest tune since I've heard people having more small issues with other higher psi tuning and yes I know there are pros and cons to every tune. My issues is the weird low boost readings in first gear other than that I'm pleased with everything since it's my daily driver. Have you guys ever had a change in your first gear boosting with cold weather changes?

[MedicCarter]

I only hit 15 psi with apr 2+ in first gear, but no FMIC

That seems low I would have it re flashed since I have always hit 18 or better even before the FMIC.

[Jhad]

i think you are chasing a ghost based on the info provided. colder temps can do that... and its only 1st gear lol. Maybe it just me, but i usually dont go wot too often from a dig, and i dont do 1st gear pulls.

[Der Konig]

I hit 20 on 2+ sometimes, typicall about 19psi. That is weird, failing n80 or you guys that are pulling lower than that need to make the adjustment that corrects the low boost issue, if you search low boost issue it will come up.

Now to OP: Correct me if I am wrong but 1st gear is mainly there to get the car moving and doesn't normally build very much boost. I don't build much in first at all, my thoughts were because it isn't a very load heavy gear so hard to build. I have seen it explained as a bike, try pedaling in a really low gear and you pedal a whole lot without creating much work since you distance is small, just expending a bunch of energy. Now do the same in a higher gear and you are creating more work under the same load so you are "loading" the engine more, resulting in more boost. When cruising at around 45-50 put it in fifth and go WOT and watch the boost gauge. It should spike to 20 or a little higher.

And for the FMIC guys, I am sure you increased the piping diameter when you installed the FMIC to at least 2.5-3" which would result in a boost loss due to logic. In simple terms blow through a big gulp straw than a coffee straw, big pressure difference. So while you may be cooling more you have lost some pressure within the system. Also now that I think about it that means the same amount of air will take up less volume creating less pressure than hot air so the cooled from the FMIC can also cause a slight boost loss.

Does that make sense or am I justifying my no boost issue in first?

[MedicCarter]

I hit 20 on 2+ sometimes, typicall about 19psi. That is weird, failing n80 or you guys that are pulling lower than that need to make the adjustment that corrects the low boost issue, if you search low boost issue it will come up.

Now to OP: Correct me if I am wrong but 1st gear is mainly there to get the car moving and doesn't normally build very much boost. I don't build much in first at all, my thoughts were because it isn't a very load heavy gear so hard to build. I have seen it explained as a bike, try pedaling in a really low gear and you pedal a whole lot without creating much work since you distance is small, just expending a bunch of energy. Now do the same in a higher gear and you are creating more work under the same load so you are "loading" the engine more, resulting in more boost. When cruising at around 45-50 put it in fifth and go WOT and watch the boost gauge. It should spike to 20 or a little higher.

And for the FMIC guys, I am sure you increased the piping diameter when you installed the FMIC to at least 2.5-3" which would result in a boost loss due to logic. In simple terms blow through a big gulp straw than a coffee straw, big pressure difference. So while you may be cooling more you have lost some pressure within the system. Also now that I think about it that means the same amount of air will take up less volume creating less pressure than hot air so the cooled from the FMIC can also cause a slight boost loss.

Does that make sense or am I justifying my no boost issue in first?

I have heard that cars pull less boost in first and either I never really paid attention or it's the cold weather or some ghost. I used to pull higher with and without the FMIC but yes all other gear but first are doing the same. About the FMIC I did increase the pipe diameter but the piping is less with less bends so I'm going to say it's roughly close to the same maybe a bit more volume but not enough to change the psi in my opinion. I'm thinking about replacing the N80 I have been checking for info about what happens when they fail but I haven't lost all boost or have and codes or anything that seems to show its the N80 other than first gear boost readings.

[MedicCarter]

i think you are chasing a ghost based on the info provided. colder temps can do that... and its only 1st gear lol. Maybe it just me, but i usually dont go wot too often from a dig, and i dont do 1st gear pulls.

Well maybe that it the cold haha. I only have been pulling it hard with this problem to try and find the issue since it's bugging me.

[Hugh@EuropaParts]

I think the RPM's rise so quickly in 1st that you would never really see "full boost" ... especially 20lbs

[Schweini]

I think the RPM's rise so quickly in 1st that you would never really see "full boost" ... especially 20lbs

this is true

while in "S" mode, I have never seen full boost since the engine revs way too fast as well. I think I see maybe 10psi at most? But the butt dyno is definitely registering full boost

[Jhad]

Well maybe that it the cold haha. I only have been pulling it hard with this problem to try and find the issue since it's bugging me.

i know the feel when something bugs me. I would be concerned if your vac was going crazy, or if you boost fluttered, etc. i think your g2g

[MedicCarter]

I think the RPM's rise so quickly in 1st that you would never really see "full boost" ... especially 20lbs

Yeah but would it only show 3-8 psi even at 5,500-6k? Could my N80 fail without codes and just boost reading issues? Could it cause anything else I might feel while driving? I have researched it but it seems like power loss and codes are the main signs.

[Hugh@EuropaParts]

Yeah but would it only show 3-8 psi even at 5,500-6k? Could my N80 fail without codes and just boost reading issues? Could it cause anything else I might feel while driving? I have researched it but it seems like power loss and codes are the main signs.

Laggy boost gauge? If it's just first I wouldn't worry about it... if you're seeing 8psi in 3,4,5 then there is an issue.

[Der Konig]

Yes it is possible that it could not cause faults. You could feel a slowrr build of boost in other gears followed by a lower psi spike and hold. The n80 is different than the diverter valve. It could just be releasing a little boost, I'm trying to find the thread on it that someone was having the issue and fixed the lower boost by adjusting the n80. The only issue is that it can be dangerous since it is essentially a manual override that allows your car to build more boost and should only be done if you are having real issues. It acts kind of like a secondary waste gate...just can't find the thread. I'll keep looking though. I think the op doesn't have an issue but more for info for those pulling less than 18-19psi on 2+

Here we go...it's adjustment of the wastegate/actuator rod

http://www.audizine.com/forum/showthread.php?t=419180

Sent from my SM-N900V using Tapatalk

[Charles.waite]

Well maybe that it the cold haha. I only have been pulling it hard with this problem to try and find the issue since it's bugging me.

My b6 JUUUUST barely hits 20 in 1st and 2nd, and 3rd and up it hits 23 at WOT. It has more to do with the amount of load, the narrow spool band and how fast the engine gets out of the peak boost band in 1st and even 2nd.

It you weren't hitting above 15 I would be worried. 18 if fine. As long as you're seeing the proper boost in higher gears its not a big deal.

[MedicCarter]

Yes it is possible that it could not cause faults. You could feel a slowrr build of boost in other gears followed by a lower psi spike and hold. The n80 is different than the diverter valve. It could just be releasing a little boost, I'm trying to find the thread on it that someone was having the issue and fixed the lower boost by adjusting the n80. The only issue is that it can be dangerous since it is essentially a manual override that allows your car to build more boost and should only be done if you are having real issues. It acts kind of like a secondary waste gate...just can't find the thread. I'll keep looking though. I think the op doesn't have an issue but more for info for those pulling less than 18-19psi on 2+

Here we go...it's adjustment of the wastegate/actuator rod

http://www.audizine.com/forum/showthread.php?t=419180

Sent from my SM-N900V using Tapatalk

I had seen that modification thread and yeah I'm not going to try and do it. My car is mild compared to some of the crazy cars on this forum I just want it to last and I'm a perfectionist so when something seems off I have to fix it. Thanks for the input I think I will change my N80 soon just to see if it changes anything besides its cheap and relatively easy except for my gorilla hands haha.

[MedicCarter]

My b6 JUUUUST barely hits 20 in 1st and 2nd, and 3rd and up it hits 23 at WOT. It has more to do with the amount of load, the narrow spool band and how fast the engine gets out of the peak boost band in 1st and even 2nd.

It you weren't hitting above 15 I would be worried. 18 if fine. As long as you're seeing the proper boost in higher gears its not a big deal.

I swear I was able to hit 18 before in first that's why I was concerned and it's been bugging me.

[yungcotter]

I can hit 17-19 without trying and every now and then hit 20+. Ive also tweaked my wastegate so that probably has something to do with it.

[MedicCarter]

I can hit 17-19 without trying and every now and then hit 20+. Ive also tweaked my wastegate so that probably has something to do with it.

That's what I swear I was doing before but I haven't touched my wastegate.

[Obsidian]

I'm stage 1 and I average 18-20, however I did notice on my logging the other day I did peak up to 24 a few different times.

[MedicCarter]

I'm stage 1 and I average 18-20, however I did notice on my logging the other day I did peak up to 24 a few different times.

Wow that seems pretty high for an APR tune. The best I ever saw was 21 and it was only once. What else have you done besides your tune? What stage are you?

[Obsidian]

Wow that seems pretty high for an APR tune. The best I ever saw was 21 and it was only once. What else have you done besides your tune? What stage are you?

Just stage 1 and aFe drop in filter. Previously the highest I ever saw was 22 until the other day.

I did however cut out a significant amount of my stock airbox last weekend to allow for more airflow but I didn't think it would give much benefit. Also I'm sure my altitude and temp is definitely playing a role.

EDIT:

Hopefully I will be getting this guy in soon after Xmas and upgrading to stage 2 though. Just picked it up from getting a nice ceramic coat this week. Thanks again to Hugh for getting me such a great deal on this TP and to Discover for picking up half the tab on this one [:D]

http://i1121.photobucket.com/albums/l504/AZgts/Mobile%20Uploads/IMG_20131216_163540_zpsekyjpaf1.jpg
http://i1121.photobucket.com/albums/l504/AZgts/Mobile%20Uploads/IMG_20131216_163449_zpsgmyqqql9.jpg
http://i1121.photobucket.com/albums/l504/AZgts/Mobile%20Uploads/IMG_20131216_163505_zpsfgf9uukt.jpg
http://i1121.photobucket.com/albums/l504/AZgts/Mobile%20Uploads/IMG_20131216_163456_zpssp13ijuv.jpg

[The_Ocho]

I'm stage 1 and I average 18-20, however I did notice on my logging the other day I did peak up to 24 a few different times.


Wow that seems pretty high for an APR tune. The best I ever saw was 21 and it was only once. What else have you done besides your tune? What stage are you?

APR stage 1 here and I see the same numbers. I have a custom intake not that it matters

[MedicCarter]

APR stage 1 here and I see the same numbers. I have a custom intake not that it matters

Well I feel cheated haha maybe my N80 is going on me.

[rongeur]

FWIW, I have been running APR stage 2 and 2+ for 2 years and tend to see my peak boost trim down in colder weather (17-18) and higher in warm weather (19-21). The ECU adapts to ambient conditions and driver habit. Try resetting your service interval and clear any DTCs and see if the tune "livens up". Some disconnect the battery overnight to reset fuel trims etc to get the same effect.

[Charles.waite]

Remember boost is only a measure of pressure differential. It doesn't actually directly correlate to power.

Hence why a gtrs at 20psi makes a shit ton more power than a k03 at 20 psi.

[MedicCarter]

FWIW, I have been running APR stage 2 and 2+ for 2 years and tend to see my peak boost trim down in colder weather (17-18) and higher in warm weather (19-21). The ECU adapts to ambient conditions and driver habit. Try resetting your service interval and clear any DTCs and see if the tune "livens up". Some disconnect the battery overnight to reset fuel trims etc to get the same effect.

I'm not showing any codes though? how will reseting the service intervals change anything? I appreciate the ideas just trying to understand why it would help?

[MedicCarter]

Remember boost is only a measure of pressure differential. It doesn't actually directly correlate to power.

Hence why a gtrs at 20psi makes a shit ton more power than a k03 at 20 psi.

I get that Charles I guess it's more about the gauge and change in the reading now. It's bugging me and I can't figure out the change in the boost readings. I'm going to order a new N80 and then go from there I'm also changing my plugs tomorrow but I do that at every oil change because their cheap.

[MedicCarter]

Shit I've been saying N80 and what I meant was N75 the wastegate frequency control valve. Does anyone have any experience with this failing with no codes? could that cause boost pressure variances? It seems like I could have a partially failing one to me but that's just me next thought.

[martinofski]

Shit I've been saying N80 and what I meant was N75 the wastegate frequency control valve. Does anyone have any experience with this failing with no codes? could that cause boost pressure variances? It seems like I could have a partially failing one to me but that's just me next thought.

I am in that boat too. Changed alot of stuff, data logged to find the issue but haven't changed that N75 yet, just because the 2 bolts are hard to reach and stuck in some rust. I am being lazy. I will do it this afternoon I think.
I don't have code except when I do a specific action which is : Start the car when warm, stall it, restart it quickly. Then I get some codes, related to the N80 from what I remember. The car get in safe mode then. I reset everything and restart the car again, back to normal.

Parts I did changed since the issue : PCV to catch can, diverter valve to forge, some clamps for hoses, spark plugs, air filter (not that it would matter).
What I will be doing next: N75, fuel filter, clean MAF, check turbo...then Coil pack.

Before I end up adjusting the wastegate, I want to make sure all avenue have been looked at. but it might be the wastegate spring which is tired.

I just don't understand why my air flow hit 195g/s, my requested and actual boost are the same, and I can't hit more than a steady 10psi while peak vary from 13 to 16 but drop quickly.

I'll try to keep you posted when I'll change that N75.

[rongeur]

I dont get any meaningful codes either but for some reason, every time I scan / clear / reset service reminder it also reset the ECUs adaptations as well.

[Obsidian]

FWIW, I have been running APR stage 2 and 2+ for 2 years and tend to see my peak boost trim down in colder weather (17-18) and higher in warm weather (19-21). The ECU adapts to ambient conditions and driver habit.

Ya, its just got to "normal" weather temps here in the last couple weeks aka 70*-80*. Just a bit of insight on my car over the last year or so and I'm not even sure if any of this matters but I have had the PCV, LPFP sensor and one other thing I can't remember replaced under warranty right when I got the car about a year and a half ago now. Six months ago my rubber diaphragm ripped in my DV so I upgraded to the revision D. Now most recently I just have my intake cam replaced with the revision B, and the cam follow replaced under warranty. Obviously since they were in there I got all new gaskets and good stuff. So idk... maybe that stuff is contributing to the high boost but who knows because I can't say I do.

Like I said before I did notice the increase after I cut up my stock airbox for more flow (wish I would have taken pics), so that may be playing a role as well, but there are just too many variables to really pinpoint anything.

[MedicCarter]

I am in that boat too. Changed alot of stuff, data logged to find the issue but haven't changed that N75 yet, just because the 2 bolts are hard to reach and stuck in some rust. I am being lazy. I will do it this afternoon I think.
I don't have code except when I do a specific action which is : Start the car when warm, stall it, restart it quickly. Then I get some codes, related to the N80 from what I remember. The car get in safe mode then. I reset everything and restart the car again, back to normal.

Parts I did changed since the issue : PCV to catch can, diverter valve to forge, some clamps for hoses, spark plugs, air filter (not that it would matter).
What I will be doing next: N75, fuel filter, clean MAF, check turbo...then Coil pack.

Before I end up adjusting the wastegate, I want to make sure all avenue have been looked at. but it might be the wastegate spring which is tired.

I just don't understand why my air flow hit 195g/s, my requested and actual boost are the same, and I can't hit more than a steady 10psi while peak vary from 13 to 16 but drop quickly.

I'll try to keep you posted when I'll change that N75.

Thanks man I appreciate the info I have changed most of the stuff you have if not checked it because it was still fairly new. Hell my car only has 44k on it I'm thinking the N75 could be my issue with a partial failure because my boost also doesn't seem to hold as long but hell I don't know. I probably won't be messing with the wastegate because well I just don't feel like moding it. Keep me updated on your N75 I would be interested if your boost pressures increase or hold longer after the change.

[martinofski]

I ended up not changing it yet...passed 2h hours under the car just trying to remove the 2 damn screws which are rusted...I am not even sure it is the issue, since my requested boost and actal one are exactly the same. I will get the damn thing to the audi garage after the christmas vacation. Oh well, at least I changed my cam follower on the fuel pump, even though the previous was still ok and I cleaned my MAF.

I unplugged my battery for 5 min and plugged it back. Got 18.5psi peak on the first push. then it dropped back down to 13psi, holding 10...:(.
I guess it is either a gas related issue, or a spark one.
I might try to go talk to the garage owner monday, if he is opened.

[MedicCarter]

I ended up not changing it yet...passed 2h hours under the car just trying to remove the 2 damn screws which are rusted...I am not even sure it is the issue, since my requested boost and actal one are exactly the same. I will get the damn thing to the audi garage after the christmas vacation. Oh well, at least I changed my cam follower on the fuel pump, even though the previous was still ok and I cleaned my MAF.

I unplugged my battery for 5 min and plugged it back. Got 18.5psi peak on the first push. then it dropped back down to 13psi, holding 10...:(.
I guess it is either a gas related issue, or a spark one.
I might try to go talk to the garage owner monday, if he is opened.

Hmmmm I'm pulling my plugs in a few min once my car cools off a bit but I don't think that's the issue. Nothing on my car is rusted my engine bay is actually pretty dam clean but I wipe it down every time I open the good (yeah I'm that OCD guy haha). Hopefully I will get mine out easier I'm ordering my N75 today I may see if JHM has them since they are close and usually good on prices from what I hear.

[martinofski]

I am up north in canada. Hard for me to test my boost anyway right now, must have about 3inch of snow in the roads. I keep on spinning [evilsmile].

Keep me posted.
I cnaged my plugs the other day, helped a little to smooth the engine, but nothing boost wise.

[MedicCarter]

Well plugs were nice and tan like every time I've changed them. I gapped at .034 my last set were at .036 and I didn't see any difference so I'm going in between the .032 and my old gap. The weird thing was right out of the box they were gapped at .040 but either way they are done and I ordered the N75 from JHM. The new N75 didn't come with the hoses too so we will see how hard to pull those locking clamps off it is. I'm hoping that's easy because my bolts are clean and look like they just came out of the factory unlike martinofskis. Has anyone pulled the N75 without putting on new hoses? Does anyone have any tips that might help, it looks strait forward but I figured I would ask.

[MedicCarter]

Well today I got around to replacing my N75. I first have to say the person who invented those factory clamps is the devil and my hands are cut up from all the prying other than the removal is easy the clamps just made it tedious. I would like to thank JHM for the quick shipping I ordered the part on Friday afternoon and it was here Saturday while I was at work. Well I took the car for a test drive and at first the boost didn't seem to be changed so I pulled over and re calibrated my throttle body just to make sure everything was fresh and reset for the testing. I took it out and opened it up from a stop a few times at first it was only pulling 14 but that was better ham before and now it's back to pulling 18-19 psi. I'm guessing as I drive it a bit more it will re calibrate everything and continue to pull like before. Thanks everyone for the help and suggestions I really appreciate this forum it is awesome to have help so quick and by a lot of people who are much more knowledgable than myself.

[Amarao]

I just replaced my N75 the other day, I was getting some random events where I'd make no boost at all, and no codes. Aside from having boost again I'm now hitting 20 psi more often, and even 24 psi once or twice. I really need to break out the laptop and do some data logging to see what's up with that.

[martinofski]

Well today I got around to replacing my N75. I first have to say the person who invented those factory clamps is the devil and my hands are cut up from all the prying other than the removal is easy the clamps just made it tedious. I would like to thank JHM for the quick shipping I ordered the part on Friday afternoon and it was here Saturday while I was at work. Well I took the car for a test drive and at first the boost didn't seem to be changed so I pulled over and re calibrated my throttle body just to make sure everything was fresh and reset for the testing. I took it out and opened it up from a stop a few times at first it was only pulling 14 but that was better ham before and now it's back to pulling 18-19 psi. I'm guessing as I drive it a bit more it will re calibrate everything and continue to pull like before. Thanks everyone for the help and suggestions I really appreciate this forum it is awesome to have help so quick and by a lot of people who are much more knowledgable than myself.

Well thanks for the feedback, I'll take another shot at removing the old N75. It's plastic anyway, so nothing that is impossible to break out of there. Hope it does the job for me too!