Check Engine Light: "Lack of Boost" / "Under Boost"

[BaByBoiGsxR]

The wife's car is a 2.0T CVT

I don't recall the actual code that was shown when the shop's laptop was plugged into the car.

The tech said that it's "lacking boost"or "it's under boost".

Just a few weeks ago, I had the shop replace the diverter valve (OEM).

Since it's the wife's car, I don't really spend as much time on it as I do on my own car. But I'm still learning about maintenance, repairs, and mods on the car. Thank goodness for the Audi forum, right?

I'm planning to have the shop diagnose the check-engine-light soon. Unfortunately, they're booked. And the earliest appointment is on June 29th (Audi / VW Performance shop). Therefore, I'd like to start gather ideas and potential solutions in case I'm able to fix it myself.

The car does feel a bit sluggish upon normal take off from a complete stop. I guess the best way to describe it is... it "feels like it's struggling". Might not be as bad as it sounds, but that's the best description I have.

If you have ideas, suggestions, or opinions, please feel free to throw them my way.

I have a long list of items to get done to the car (maintenance-wise), and this added issue is definitely bugging me (...and the wife).

Thanks in advance.



Repairs / mods already done...

• Transmission service
• Diverter valve
• Purge valve
• Valve cover gasket
• PCV gasket
• Spark plugs
• Coil pack
• Oil changes
• Drilled front rotors
• Akebono front pads
• Stigan turbo (with gaskets, bolts, etc.)
• Turbo cut-off valve (twice)
• Paint correction
• White LED city lights

Repairs to be done...

• Replace rear rotors (maybe)
• Replace rear pads (maybe)
• Flush brake fluid
• Replace cam follower
• Replace engine oil cap ring
• Replace air filter
• Replace crankcase valve gasket (still trying to confirm if it's leaking)
• ...there's more. I just can't remember the rest at the moment.

Mods I plan to get done...

• Tint
• Crank pulley
• APR tune
• Front license plate delete
• RS4 wheels (replicas)
• Spacers all around
• Lowering springs (just enough to minimize the fender gap. Wife doesn't want it "that low".)
• Opt7 LED headlights (currently have halogens. Considering to swap into projectors.)
• LED fog lights
• Rear diffuser for quad tips
• Quad muffler tips
• Xpel clear bra
• Upgrade to OEM navigation system & add back-up camera
• Replace climate control (current one is peeling)
• White license plate bulbs

*** Update as of 6/19/16 ***

I was at a red light this morning. As soon as the light turned green, I left off the brake and gently pressed on the gas. The engine revved for two seconds then engaged / jerked forward and slowly started to move forward. The car was really hesitating and struggling up till about 40 mph. It happened during the next 4 complete stops I made.

After making it to my destination, I was out of the car for about half an hour. Then when I drove it home, it did the same thing. Except this time, instead of pressing the gas right away, I gave it a few seconds and eased on the gas. That's when it didn't really jerk anymore. It was a similar feel as if the car was going to die on the road.

Anyone experience this?



*** Update as of 6/20/16 ***

Took the car in and left it for the entire day at the shop.
Got a call saying that the turbo cut-off valve had to be replaced. It was in four pieces.
The shop owner also said that the turbo ring was replaced due to oil leaking into the inter-cooler.
The inter-cooler was flushed.

I asked him if there were any other issues he or his tech may have caught during the diagnosis. He said all looks pretty good.
He said that I have to keep an eye out for smoke coming out of the tail-pipes. If so, that would be a sign that the turbo is really bad and should be replaced (due to the 1/4 to 1/2 quart of oil that leaked into the inter-cooler.

The wife picked up the car at 4pm. She drove it back to work. Afterwards, she ran some short errands. At around 7pm, she calls me saying that the check-engine-light came back on. Argh!!! A bit frustrating. The shop offers a 2 year warrant on their parts and labor. Looks like I'm making another trip down there to see what this other problem is.



*** Update as of 6/21/16 ***

The car was brought back to the shop and diagnosed.
The shop owner said that the new turbo cut-off valve is ruined due to the massive oil leak from the turbo.

Now I'm frustrated even more and need some assistance / suggestions / opinions from those that have experience with my issue.

I've been quoted $710 for labor.

As far as the turbo itself, are there any quality options? I don't think I want to do an "upgrade" if it involves needing other upgraded parts (downpipe, inter-cooler, etc.). I'm looking for a simple direct swap.

Cost is somewhat a factor for me because I still have other necessary repairs to do.

What brand(s) do you recommend?

Are there any other very reputable yet inexpensive Audi shops that you recommend in Southern California? (LA County / Orange County)






*** Update as of 7/24/16 ***

I should have posted a final update 3 weeks ago regarding the issue that the wife's car was having. Here it is... (along with another issue / question)

OEM turbo was replaced with a brand new Stigan turbo. The power is definitely there. It's such a different feel now that the turbo now works correctly.

However... there is something that the wife told me about. Then when I drove it, I noticed it as well.

Somewhere on this thread, I may have mentioned that when the turbo was having issues, there was a heavy hesitation with the car from a complete stop. As in... it wouldn't have power till you reached 40 mph (which took a long time). That is no longer an issue. No more check engine light, no more "lunging forward" when the brake is released, etc.

What I noticed this weekend was... there's something still not feeling 100% when taking-off. There's still a very light hesitation. It's not bad to the point where there's no power. It just doesn't pull right away when you give it some gas (normally). It takes a second or two for it to kind of pick up and go. When the car is in motion, there's no problem (at least I haven't noticed anything). But it always happens from a complete stop. Is there something else that the technicians and myself could have over-seen?

Would the car react this way if I have a faulty cam follower?

If you scroll up to the top to the list of "Repairs already done...", you can see what I've completed. From there maybe I can get suggestions and/or opinions on what may be causing the minor take-off hesitation.

Thanks in advance again.

[hemantpd1]

CEL code would be useful to diagnose. You can go to some automotive shop where they pull the code for free if it is generic one. Any weird noise in the engine compartment? It may be turbo bypass valve or may be boost leak from some pipe.

[RakkCity]

Step 1) Get your own VAGCOM
Step 2) Pull the exact code, underboost is represented by a couple different codes, depending on whether it's a mechanical failure, intermittent electronics failure, or permanent electronics failure.

My car had some codes for P0299 - Intermittent Underboost, currently diagnosing.

If mechanical, could be your DV installed wrong or otherwise faulty, could be the wastegate with too much play, could be a boost leak somewhere in the intake tract.
If electrical, could be N75 Wastegate controller, could be the electrical part of your DV, could be your MAP sensor or a dirty MAF.

[BaByBoiGsxR]

CEL code would be useful to diagnose. You can go to some automotive shop where they pull the code for free if it is generic one. Any weird noise in the engine compartment? It may be turbo bypass valve or may be boost leak from some pipe.

No noise that I'm aware of.
Is the turbo bypass valve the same as the diverter valve?
I googled it, and they look the same.

Step 1) Get your own VAGCOM
Step 2) Pull the exact code, underboost is represented by a couple different codes, depending on whether it's a mechanical failure, intermittent electronics failure, or permanent electronics failure.

My car had some codes for P0299 - Intermittent Underboost, currently diagnosing.

If mechanical, could be your DV installed wrong or otherwise faulty, could be the wastegate with too much play, could be a boost leak somewhere in the intake tract.
If electrical, could be N75 Wastegate controller, could be the electrical part of your DV, could be your MAP sensor or a dirty MAF.

I would like to safely assume the diverter valve was installed correctly. It's a performance shop that work only on Audi's and VW's. I would like to think they know what they're doing.
I don't know much about these engines and its setup, but hopefully it is just one of those items you mentioned.

Now that I think about it... I don't think my wife and I know how the car is really supposed to feel with normal boost. Since we've purchased the car in February (this year), we've always been trying to repair / replace something faulty.

[Sanjman]

How many miles on the car? Have you or your wife look at the exhaust while the other drives away to see if there is smoke coming out of the tail pipes which could mean oil or coolant burning up. You can also just use a standard obdii reader to see the engine codes from autozone or oreilly etc. For your type of failure a vag com would definitely help to diagnose it.

1. Check for oil leaks in the engine bay like valve cover timing chain cover heat plates pcv system.
2. Check for air leaks like cracked intercooler hoses etc.
3. Check turbo shaft play
4. Compression test on all cylinders


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[esandes]

replace the air filter. a clogged filter caused an underboost code for my car.

[BaByBoiGsxR]

CEL code would be useful to diagnose. You can go to some automotive shop where they pull the code for free if it is generic one. Any weird noise in the engine compartment? It may be turbo bypass valve or may be boost leak from some pipe.

How many miles on the car? Have you or your wife look at the exhaust while the other drives away to see if there is smoke coming out of the tail pipes which could mean oil or coolant burning up. You can also just use a standard obdii reader to see the engine codes from autozone or oreilly etc. For your type of failure a vag com would definitely help to diagnose it.

1. Check for oil leaks in the engine bay like valve cover timing chain cover heat plates pcv system.
2. Check for air leaks like cracked intercooler hoses etc.
3. Check turbo shaft play
4. Compression test on all cylinders

- As of today, the car as 116,300 miles.

- The only time black smoke comes out of the car is when you floor it completely. Since I've changed the purge valve, I haven't really noticed the smoke anymore. Not sure if the piece really helped "that" much. On another note, the car is one of many that has the oil consumption issue. It eats up oil every 1,000 miles (more or less).

- From the oil leaks that I was aware of, we had the gaskets replaced. From the two Audi performance shops that worked on the car, no one mentioned any leaks by the timing chain area.

- Turbo shaft... don't really know where to look.

- The car is going to a different shop tomorrow (never been there but it's supposed to be a performance european shop. Me being a car guy, I usually avoid general repair shops. They have to be shops that work on high performance cars / highly modified cars. Just my personal preference). I'll try to ask if they can do a compression test.

replace the air filter. a clogged filter caused an underboost code for my car.

Interesting... I never thought air filters can affect a car's performance that much (...to the point where it's struggling at take off).

[KingWulfgar]

- As of today, the car as 116,300 miles.

- The only time black smoke comes out of the car is when you floor it completely. Since I've changed the purge valve, I haven't really noticed the smoke anymore. Not sure if the piece really helped "that" much. On another note, the car is one of many that has the oil consumption issue. It eats up oil every 1,000 miles (more or less).

- From the oil leaks that I was aware of, we had the gaskets replaced. From the two Audi performance shops that worked on the car, no one mentioned any leaks by the timing chain area.

- Turbo shaft... don't really know where to look.

- The car is going to a different shop tomorrow (never been there but it's supposed to be a performance european shop. Me being a car guy, I usually avoid general repair shops. They have to be shops that work on high performance cars / highly modified cars. Just my personal preference). I'll try to ask if they can do a compression test.




Interesting... I never thought air filters can affect a car's performance that much (...to the point where it's struggling at take off).

I doubt you need a compression test. Typical culprits are DV (bypass valve), a boost leak somewhere, or a flaky wastegate. You've already covered the DV so you may want to have them pressure test the system. You really need the full code, though. Generic is usually P0299, but there will be a VAG-specific code along with that.

Here's a good example of a sloppy wastegate and the codes it causes: https://www.youtube.com/watch?v=efWOPtAw1Ss

[hemantpd1]

No noise that I'm aware of.
Is the turbo bypass valve the same as the diverter valve?
I googled it, and they look the same.

Yes, they are the same and I see that u have already changed it, hopefully with the latest revision.

check for faulty wastegate as many have suggested and also for boost leak somewhere in intake system.

[BaByBoiGsxR]

Posted an update at the bottom of my original post.

[BaByBoiGsxR]

Another failed update posted.
Looking for assistance.

[tangj2]

Is your code P0299?
My code was triggered by near faulty turbocharger (turbo's scoring on the compressor housing from the blades due to excessive shaft play
) It doesn't generate enough boost. It has 122,000mile on the clock. Had a piston type DV. N75 is fine. no leak anywhere.
Have somebody to do a smoke test and check your turbo.

[BaByBoiGsxR]

It's worse than that.
According to the shop owner, the turbo is leaking excessive oil (and into the inter-cooler) and needs to be replaced asap.
I need to find inepensive, high quality turbo replacement options.

[RakkCity]

It's worse than that.
According to the shop owner, the turbo is leaking excessive oil and needs to be replaced.
I need to find inepensive, high quality turbo replacement options.

There's a guy on a facebook group selling motors. I asked him about a k03 for my car and he said he's got one with 33k miles for $400. PM me and I'll link you to his facebook

[BaByBoiGsxR]

^
PM sent

[Biged243]

What year is your car? Silver or black valve cover? Make sure you check the cam follower, that's unrelated but still check it. The black valve covers can fail and dump oil. Not saying that your turbo ain't bad, but more info like from a Ross tech would be very helpful.

[BaByBoiGsxR]

I never thought that I'd be saying this... but can somebody school me on the type of turbo that I currently have?

It's a 2.0T FSI CVT. The sticker shows... *BWT 049077*

Not really sure what the BWT means. Engine type?


The reason I ask is because I'm trying to figure out what is compatible with the car.

I came across a brand new Stigan turbo for $800. Is that reasonable?

Or a brand new OEM for $1,000.




Somewhat irrelevant, but... I thought of the Frankenturbo F23L Hybrid ($1,499), but I don't think it'll be "that" much better if mods were added. I'm guess the power output would be the similar for either the Frankenturbo or the Stigan, right?

[Sanjman]

find a used one K03 turbo from the audizine classifieds for 250 or less! Rebuild the old turbo by yourself and keep it as a backup or put it back in.

If you're going to "upgrade" your turbo then go with a K04 turbo or JHM's kits.

Frakenturbo is not worth it. They have caused customers on AZ nothing but pain, agony, and sadness. You can also look for an S3 K04 kit

[BaByBoiGsxR]

What year is your car? Silver or black valve cover? Make sure you check the cam follower, that's unrelated but still check it. The black valve covers can fail and dump oil. Not saying that your turbo ain't bad, but more info like from a Ross tech would be very helpful.

Car is an '08.
Black Valve cover.
Haven't checked the cam follower (...yet).

I'm very much trying to get second opinions from others who think it might "not" be the turbo. But I mean... the shop owner said himself that the turbo is leaking oil. He showed me the old cut-off valve drenched in oil and broken into four pieces. Even if the cam follower was completely out, it wouldn't leak into the turbo, right?

I also had the valve cover gasket replaced last weekend at another shop. They said that everything looked good (at least in the valve cover area).

find a used one K03 turbo from the audizine classifieds for 250 or less! Rebuild the old turbo by yourself and keep it as a backup or put it back in.
If you're going to "upgrade" your turbo then go with a K04 turbo or JHM's kits.
Frakenturbo is not worth it. They have caused customers on AZ nothing but pain, agony, and sadness. You can also look for an S3 K04 kit

I don't know if I trust myself rebuilding a turbo. I'm pretty car savvy for the most part, but there are certain parts of a car I refuse to touch. Only because if I don't do something correctly, it may potentially lead to a bigger issue. LoL.

[RakkCity]

I don't know if I trust myself rebuilding a turbo. I'm pretty car savvy for the most part, but there are certain parts of a car I refuse to touch. Only because if I don't do something correctly, it may potentially lead to a bigger issue. LoL.

I was curious after reading this, so I found a few DIY's.
http://nomads.eurodiscussion.net/t37...-picture-heavy

and the thread he referenced from vagdrivers.net
http://vagdrivers.net/forums/index.php?showtopic=23532
Doesn't look that hard at all, I think I might make this a project later this year.


...or just swap in a k04

[Biged243]

Car is an '08.
Black Valve cover.
Haven't checked the cam follower (...yet).

I'm very much trying to get second opinions from others who think it might "not" be the turbo. But I mean... the shop owner said himself that the turbo is leaking oil. He showed me the old cut-off valve drenched in oil and broken into four pieces. Even if the cam follower was completely out, it wouldn't leak into the turbo, right?

I also had the valve cover gasket replaced last weekend at another shop. They said that everything looked good (at least in the valve cover area).





I don't know if I trust myself rebuilding a turbo. I'm pretty car savvy for the most part, but there are certain parts of a car I refuse to touch. Only because if I don't do something correctly, it may potentially lead to a bigger issue. LoL.

The cam follower is a common failure point even in the 08's. Like I mention it was unrelated but since you don't know much about these cars I was just stating it so it would be one less head ache. It's not the black valve cover it is the silver one that usually has the problems, and it has to do with the baffles and passages built in the valve cover. Once it separates it will dump oil and give bad boost performance. And stock turbo is a ko3, look in classifies for it and don't buy the eBay replacement one since they are usually Chinese knock offs.

- - - Updated - - -

I was curious after reading this, so I found a few DIY's.
http://nomads.eurodiscussion.net/t37...-picture-heavy

and the thread he referenced from vagdrivers.net
http://vagdrivers.net/forums/index.php?showtopic=23532
Doesn't look that hard at all, I think I might make this a project later this year.


...or just swap in a k04

It's not just swap in a ko4

[BaByBoiGsxR]

Update added at the bottom of my initial post.

Looking for more assistance.

[RakkCity]

Regarding your update, my B8 with a CVT would do the same thing, to the point of annoyance. I got in the habit of pumping to gas pedal once to get the engine up, and then easing into it to accelerate. Are you sure it's not just the normal CVT/throttle easing that's supposed to increase comfort on takeoff?

Try the throttle body adjustment procedure that was bumped a few days ago, basically you turn the key on, engine off, hold throttle down all the way for 3 secs, turn key back off but keep it in ignition, wait two mins, remove key then reinsert and start. That might fix your hesistation problem.

[mtroxel]

It just doesn't pull right away when you give it some gas (normally). It takes a second or two for it to kind of pick up and go. When the car is in motion, there's no problem (at least I haven't noticed anything). But it always happens from a complete stop. Is there something else that the technicians and myself could have over-seen?

Would the car react this way if I have a faulty cam follower?

Not the cam follower. I think your just describing turbo lag. It sucks every time I hit the gas but turbos have to spin up before you get boost. I think you didn't notice it before cause your turbo never made boost.

[Sanjman]

What you're now feeling is normal. All "new" cars felt like that. Once the throttle body adapts to your style of driving it will go away or your body will adapt to the car haha. Do try the throttle body adjustment if the shop didn't.

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[BaByBoiGsxR]

Regarding your update, my B8 with a CVT would do the same thing, to the point of annoyance. I got in the habit of pumping to gas pedal once to get the engine up, and then easing into it to accelerate. Are you sure it's not just the normal CVT/throttle easing that's supposed to increase comfort on takeoff?

Try the throttle body adjustment procedure that was bumped a few days ago, basically you turn the key on, engine off, hold throttle down all the way for 3 secs, turn key back off but keep it in ignition, wait two mins, remove key then reinsert and start. That might fix your hesitation problem.

Interesting tid bit. Never knew that.
I'm definitely going to do the throttle reset within the next couple days.
I'm really hoping that changes the dynamics of the throttle sensitivity.

Not the cam follower. I think your just describing turbo lag. It sucks every time I hit the gas but turbos have to spin up before you get boost. I think you didn't notice it before cause your turbo never made boost.

I guess the turbo lag on the Audi's are different than the turbo lag on other makes. Back in 2013, my younger bro bought our mom a brand new Mercedes C250. It's a 4 cyl turbo as well. Unless because it's a much newer year (2013), the turbo lag feels completely different. It's not quick or anything, but it doesn't feel anything like the wife's car.

What you're now feeling is normal. All "new" cars felt like that. Once the throttle body adapts to your style of driving it will go away or your body will adapt to the car, haha. Do try the throttle body adjustment if the shop didn't.

LoL @ your comment.

Although the wife and I owned the car since late February 2016, I'm still learning a lot about these cars. I'm so used to the Benz scene, that some of these things are new to me.

I do have a question though...

The A4 is a CVT.
When it's on "D" (drive), does the transmission start on 2nd gear?
Then when the car is on "S" (Sport), does the car initially start on 1st gear?
(Hence, the noticeable difference in take-off)


The reason for this thought is because most Mercedes have different modes.
"C" (Comfort mode) / "E" (Economy mode)
"S" (Sport mode)
"M" (Manual mode - paddle shifters / tiptronic)

Comfort and Economy... transmission always starts on 2nd gear
Sport... transmission always starts on 1st gear
Manual... transmission always starts on 1st gear

[KingWulfgar]

It's a CVT. You don't have "gears." I'm sure there is some internal computing that is done to make a difference between Drive and Sport, but I don't know. Even when you put it in "tiptronic" mode, there are no gears. It just plays around with the internal movement of the transmission to make it feel like it.

I hate hate hate CVTs.

[BaByBoiGsxR]

It's a CVT. You don't have "gears." I'm sure there is some internal computing that is done to make a difference between Drive and Sport, but I don't know. Even when you put it in "tiptronic" mode, there are no gears. It just plays around with the internal movement of the transmission to make it feel like it.

I hate hate hate CVTs.

Good call... Although I know it's a CVT, I never seem to remember how CVT transmissions work (I'm so focused on the turbo lag issue).

Based on your comment, you probably hate CVT's just as much as my Benz forums hate BMW Smg transmissions. LoL.

[BaByBoiGsxR]

Try the throttle body adjustment procedure that was bumped a few days ago, basically you turn the key on, engine off, hold throttle down all the way for 3 secs, turn key back off but keep it in ignition, wait two mins, remove key then reinsert and start. That might fix your hesistation problem.

Not the cam follower. I think your just describing turbo lag. It sucks every time I hit the gas but turbos have to spin up before you get boost. I think you didn't notice it before cause your turbo never made boost.

Did the throttle reset this weekend (...actually, the wife did it for me. I emailed her the step-by-step directions.).
The lag isn't bad any more. Very noticeable difference.

However, the lag is noticeable when the A/C is running. I'm hoping the under-drive / crank pulley will counter that issue. My reasoning for saying so is because on my previous car (non-Audi / non-turbo), the power was "all there" even when the A/C was running. The car will pull as if the A/C was off.

Thank you for the suggestion guys (...and everyone else). Definitely helpful to do the reset.

This coming weekend, I'm going to try the reset myself and drive it hard. I'd like to see if there's any difference in the throttle response from the way I plan to reset it... vs the way the wife drove it after she had reset it. LoL. Or... what I should really do is add a bunch of performance parts. And if the wife asks... "why is the car SO MUCH FASTER?" I'll just say... no reason, I just reset the throttle and drove it hard immediately afterwards. Haha.

[Sanjman]

Did the throttle reset this weekend (...actually, the wife did it for me. I emailed her the step-by-step directions.).
The lag isn't bad any more. Very noticeable difference.

However, the lag is noticeable when the A/C is running. I'm hoping the under-drive / crank pulley will counter that issue. My reasoning for saying so is because on my previous car (non-Audi / non-turbo), the power was "all there" even when the A/C was running. The car will pull as if the A/C was off.

Thank you for the suggestion guys (...and everyone else). Definitely helpful to do the reset.

This coming weekend, I'm going to try the reset myself and drive it hard. I'd like to see if there's any difference in the throttle response from the way I plan to reset it... vs the way the wife drove it after she had reset it. LoL. Or... what I should really do is add a bunch of performance parts. And if the wife asks... "why is the car SO MUCH FASTER?" I'll just say... no reason, I just reset the throttle and drove it hard immediately afterwards. Haha.

Rule 22. Follow the rules of this forum!

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[Sanjman]

the wife did it for me

the wife drove it after she had reset it

And if the wife asks...

Rule #22 abide by the rules of this forum!

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[mtroxel]

You'll have to excuse Sanjam's double post, but this forum has survived for years because the Audizine community submits and adheres to a strict set of rules.

And Rule #22 just cannot be ignored.

[BaByBoiGsxR]

Rule #22 abide by the rules of this forum!

You'll have to excuse Sanjam's double post, but this forum has survived for years because the Audizine community submits and adheres to a strict set of rules.

And Rule #22 just cannot be ignored.

LoL. My apologies.
Rule #22 will not be broken in the future.

The good part is... at least the car feels and drives so much better.

[Sanjman]

My bad Tapatalk gave me an error on the first post

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