Overboost Problems BEW VNT17 Malone stage 4

vwnathan · May 6, 2017

Hey guys,
Just got my project done of putting in a VNT17 and getting a Malone stage 4 tune. The turbo was spiking about 25 and leveling off at 21-22 before the tune. Now with the tune it can spike upwards of 35! Usually it's about 30. This tune an setup is suppose to be doing about 21-24 with a spike of 25 tops. I do have a 3 bar map sensor installed along with the tune. No exhaust work has been done. EGTs don't run over 1,000°. I replaced the N75, no change. The checkvalve was replace with most of the vacuum system last year (rotted out actuator on the KP30). Malone insists it's a mechanical issue. I don't think it is because it boosted fine before stage 4. I had stage 1.5 before stage 4. I did calibrate the actuator on the turbo to spec, then lengthened a bit more, still spikes 30-35.

Vacuum read ~20-25Hg at the vacuum ball. At the check valve off the brake booster hose it bounces a lot. I'd say 20-40Hg? I thought this was odd. It does need a new brake booster hose. The crack has been bandaided for now but I don't think that's the cause.

My question is, can a restrictive exhaust cause over boost? Is there any other things I would check? I'm at a lost other than dumbing down the tune. I will be making some logs to submit to Malone and see if we can pinpoint where the problem is!

If anyone has any ideas, I'm open ears

thanks guys

vwnathan · May 7, 2017

So I did a log, it doesn't look good at all. Spikes appear to be around 40 PSI? Scary..

It wasn't this bad with Malone Stage 1.5 at all. As soon as I had it upgraded to stage 4 this began to happen.

http://malonetuning.com/graph/view?log=166#H8KLCADDmMK2D1kCA8KLwo5WKkrDjcONL0vDlU1JLEksTi1Rw5Ixw5QxwojDlcKJVsOKw4hMQRJUMlTDkjHDkikpKk3CjcKNBQDDti3DsMOSNAAAAA%3D%3D

Gluckmysock · May 7, 2017

I have a stage 4 tune, VNT17, EGR delete, and a straight piped exhaust. My MAP sensor is factory. I will spike to 30 but settle right back to 22-23psi. I had to adjust my actuator rod on my turbo. It starts to move right a 4" vacuum and maxes out at 18.5. I also have an aftermarket boost gauge.

Here is my log, before and after I adjusted the linkage: http://malonetuning.com/graph/view?log=171 And as per the Malone instructions, My test were done in 3rd gear, WOT 1500 rpm to redline (~4700rpm).

FWIW, Part of the Diags Malone request include group 10 with just the key on, which is your atmospheric pressure.

Enabled · May 7, 2017

You should be subtracting 1000mbar for atmospheric pressure.

What you are logging is absolute pressure (atmospheric + boost).

3000mbar absolute = 29psi boost pressure

IndigoBlueWagon · May 7, 2017

Where did you get the turbo? New or used?

vwnathan · May 7, 2017

Gluckmysock said:
I have a stage 4 tune, VNT17, EGR delete, and a straight piped exhaust. My MAP sensor is factory. I will spike to 30 but settle right back to 22-23psi. I had to adjust my actuator rod on my turbo. It starts to move right a 4" vacuum and maxes out at 18.5. I also have an aftermarket boost gauge.

Here is my log, before and after I adjusted the linkage: http://malonetuning.com/graph/view?log=171 And as per the Malone instructions, My test were done in 3rd gear, WOT 1500 rpm to redline (~4700rpm).

FWIW, Part of the Diags Malone request include group 10 with just the key on, which is your atmospheric pressure.

I included that to Malone. It was 1032 mbar

vwnathan · May 7, 2017

IndigoBlueWagon said:
Where did you get the turbo? New or used?

Turbo came from fixmyvw.com along with the map sensor.

The turbo spooled and spiked at 25 and settled at 21-22 with Malone stage 4. All I did to upgrade from that setup to stage 4 was add the 3 bar map sensor.

IndigoBlueWagon · May 7, 2017

Did Malone know about the 3-bar? If not you'll get more boost, although not 40 PSI. I'd check and make sure they wrote the tune for it even if you did tell them.

vwnathan · May 7, 2017

IndigoBlueWagon said:
Did Malone know about the 3-bar? If not you'll get more boost, although not 40 PSI. I'd check and make sure they wrote the tune for it even if you did tell them.

He did. I even swapped in the 2.5. No boost at all with the stock sensor. I was going to have my tuner follow with Malone also and see if something was missed.

Enabled · May 7, 2017

Did you see the message above?

Did you notice at idle or no load how you have 1000mbar (14 psi) of pressure?

Quit chasing your tails.

Enabled · May 7, 2017

Additional proof is that it's following requested boost quite perfectly.

vwnathan · May 8, 2017

Enabled said:
Did you see the message above?

Did you notice at idle or no load how you have 1000mbar (14 psi) of pressure?

Quit chasing your tails.

I did see that but it's still spiking 30. Wonder why the boost gauge is reading 30-35. 30 psi spikes from what I read are not good for this turbo. I'm going to try to adjust the rod on the actuator a little longer and see where I'm at.

vwnathan · May 8, 2017

Here's a couple more 3rd gear pulls to redline. my concern is the initial spike to about 30 psi (minus 14.968 for atmospheric pressure). So even though my boost gauge is spiking at 35 psi, it really isn't. The highest on the chart is 44.03 psi minus the atmosphere pressure equals out to 29 psi. I'd like it not to go past 25 tops! I'm thinking the actuator may need to go maybe two more turns longer?

vwnathan · May 8, 2017

Enabled said:
Did you see the message above?

Did you notice at idle or no load how you have 1000mbar (14 psi) of pressure?

Quit chasing your tails.

But at the spikes I'm reading 30-35 PSI on a boost gauge. Doesn't the 3bar map sensor max out at 30 PSI? So I may actually be spiking 35 PSI and the gauge is accurate. I think this to be true because the max boost in VCDS is at 29 PSI after misusing atmospheric pressure

Enabled · May 8, 2017

OK, good that you have a boost gauge to check it against. It's definitely not going into the 40's, but it probably is spiking into the 30's.

I run the VNT17 only to 20-21 psi, enough to cover the fueling I have. I have very strict control over the spikes from much trial and error in the tune, along with actuator adjustment to ~22 inch on the vacuum gauge.
My spikes do not go over 2500 mbar absolute.

vwnathan · May 8, 2017

Enabled said:
OK, good that you have a boost gauge to check it against. It's definitely not going into the 40's, but it probably is spiking into the 30's.

I run the VNT17 only to 20-21 psi, enough to cover the fueling I have. I have very strict control over the spikes from much trial and error in the tune, along with actuator adjustment to ~22 inch on the vacuum gauge.
My spikes do not go over 2500 mbar absolute.

I'm going to re-adjust the actuator to ~22Hg on the stop and see what that gives me tonight.

Thanks for all the help so far. Still waiting to hear back from Malone on what they think of the log.

vwnathan · May 8, 2017

Malone says the N75 valve is doing a poor job at regulating the boost when it spikes. The duty cycle is around 30-40% when it over boosts when it should be more like 10%. So it seems like the N75 is lagging to respond to boost control. Would that be weak vacuum? Or a DOA N75? I've tried 3 different N75 valves. Malone suggests I get a Bosch unit. I've never seen a BEW Bosch N75..

IndigoBlueWagon · May 8, 2017

I've only seen N75s from Pierburg. OE VW N75s also have a Pierburg number on them.

Owain@malonetuning · May 8, 2017

My bad, case of the Mondays (was still at home enjoying a coffee after falling/sliding/tumbling about 500ft down a snowy mountain yday), it's the pierburg mafs that often cause problems. As I said previously, the N75 is not reacting to overboost from blocks 1165 to 1183, and many other instances, such as this one.

23.59 2100 2532 2652 46.9
23.62 2121 2532 2700 48.5
23.67 2121 2544 2748 45.4
23.72 2142 2544 2784 48.9
23.77 2163 2544 2820 43.8
23.82 2163 2556 2856 45
23.87 2163 2556 2868 46.2
23.91 2184 2568 2880 48.9
23.95 2184 2580 2892 46.9
24 2205 2580 2892 50.9
24.05 2205 2592 2892 48.9
24.09 2226 2592 2892 47.3
24.14 2226 2592 2880 48.5
24.19 2226 2604 2856 50.5
24.24 2247 2604 2844 48.5
24.29 2247 2616 2832 52.9
24.34 2268 2616 2808 51.7
24.38 2289 2628 2784 52.9
24.42 2268 2616 2772 48.5

Full log here http://malonetuning.com/graph/view?...VR1V+cHlzwphNUhzDmC7CrcK8w78DPFLDicOMwqIAAAA= although I personally prefer looking at tables

This is not a software issue, we tune a lot of these. Your stage 1.5 should have been making around 18 PSI, not 22, so there's likely something else going on here.

manual_tranny · May 8, 2017

Connect your hand vacuum pump to the vacuum reservoir with the car running.

How much vacuum is in the system? This will tell you whether you have a vacuum leak which would cause the N75 to overwork itself.

However, I've never heard of a vacuum leak causing over-boost before.

vwnathan · May 8, 2017

manual_tranny said:
Connect your hand vacuum pump to the vacuum reservoir with the car running.

How much vacuum is in the system? This will tell you whether you have a vacuum leak which would cause the N75 to overwork itself.

However, I've never heard of a vacuum leak causing over-boost before.

It read about 25Hg

KERMA · May 8, 2017

in cases like this where I may suspect the car may need troubleshooting, I usually provide a 100% stock tune with a 3bar map sensor linearization. If there's a smart actuator delete or other codes from deletes that are needed, they are kept to a minimum to facilitate the troubleshooting.

If the car acts the same way then you know you need to look harder at the car, and you have proven that the tune is not at fault. (and it helps to see the stock behavior to help narrow down what the problem may be)

If the problem magically "fixes" itself with a stock flash, then maybe the tune needs revisiting. Granted with a vnt17 on a stock BEW tune it won't be ideal response but there shouldn't be any of the weird anomalies that are seen in those posted logs. It will "kinda" act like a stock turbo does, just not as snappy.

Just curious, what is the status of the egr in this car? ("dynamic?")

Owain@malonetuning · May 8, 2017

Pretty slow over there eh? The N75 valve won't be reacting as quickly to control rapid increases in boost when it's making 15 vs 24 PSI, because your deltas will be smaller. Mechanical problems are amplified when tuning, but that also makes them easier to identify. The above clip from his log is pretty straight forward, boost is over by 200-300mbar for a full second and the N75 makes no effort to correct it but rather sits around 50%. There are other sections where boost is under by 150-200mbar at higher RPM and the N75 does not close to help maintain boost. Overboost is typically around peak torque with aggressive fueling, like where I picked out one of the worst sections of the log. This car just overboosts everywhere and the N75 isn't doing it's job. This is a stock nozzle VNT17 3 bar BEW, have tuned a couple.

Here's another clip of his log

1.45 2268 1692 1416 74.2
1.49 2289 1812 1428 88.8
1.54 2310 1956 1428 95.5
1.59 2331 2088 1452 90.3
1.63 2331 2124 1464 81.3
1.69 2352 2160 1488 85.2
1.73 2373 2244 1524 95.5
1.77 2394 2556 1584 95.5
1.82 2436 2676 1632 93.9
1.87 2457 2688 1692 78.1
1.92 2478 2700 1800 70.6
1.96 2520 2700 1884 65.9
2.01 2562 2712 2016 58.8
2.06 2583 2712 2124 54.4
2.10 2625 2712 2220 52.5
2.14 2667 2712 2328 48.1
2.19 2709 2712 2496 38.7
2.25 2772 2712 2616 35.5
2.29 2793 2712 2736 32.4
2.34 2856 2712 2880 28.4
2.38 2898 2712 2952 32
2.43 2961 2712 3000 41
2.47 3003 2712 3000 46.6
2.53 3024 2712 2964 52.5
2.57 3066 2712 2928 54.8
2.62 3087 2712 2880 53.7
2.67 3213 2712 2856 49.7
2.71 3213 2712 2856 46.2
2.76 3276 2712 2856 43
2.80 3234 2712 2856 43.4
2.85 3255 2712 2868 41.4
2.90 3318 2712 2892 38.3
2.94 3360 2712 2904 35.9
2.99 3381 2712 2940 35.1
3.04 3423 2712 2952 35.5
3.08 3465 2712 2952 36.7
3.13 3507 2712 2952 36.7
3.18 3549 2712 2952 37.5
3.23 3591 2700 2940 34.7
3.27 3612 2688 2928 35.5
3.32 3654 2688 2928 33.9
3.37 3675 2676 2916 32.4
3.41 3738 2664 2904 31.6
3.46 3780 2664 2904 31.2
3.50 3801 2652 2892 31.6
3.56 3822 2652 2880 32.4
3.60 3864 2640 2868 31.6
3.65 3906 2640 2844 31.6
3.70 3948 2628 2820 31.6
3.74 3969 2628 2808 32.7
3.78 3969 1524 2784 0.8
3.83 3822 1128 2760 0.8
3.88 3801 1116 2712 0.8

Note how the N75 valve is closing while the vehicle is over boosting. It also took until 2700RPM to meet the requested boost value, when these turbos comfortably make that 500rpm lower. That suggests actuator adjustment might also be needed.

vwnathan · May 9, 2017

KERMA said:
in cases like this where I may suspect the car may need troubleshooting, I usually provide a 100% stock tune with a 3bar map sensor linearization. If there's a smart actuator delete or other codes from deletes that are needed, they are kept to a minimum to facilitate the troubleshooting.

If the car acts the same way then you know you need to look harder at the car, and you have proven that the tune is not at fault. (and it helps to see the stock behavior to help narrow down what the problem may be)

If the problem magically "fixes" itself with a stock flash, then maybe the tune needs revisiting. Granted with a vnt17 on a stock BEW tune it won't be ideal response but there shouldn't be any of the weird anomalies that are seen in those posted logs. It will "kinda" act like a stock turbo does, just not as snappy.

Just curious, what is the status of the egr in this car? ("dynamic?")

EGR system is intact (due to the fact that it all still works) and is set as dynamic in the tune. It has been this way for about a year now. The smart actuator is still there. The 3 bar map sensor is new, OEM. I really don't believe it has anything to do with the tune, but it was strange how much the boost increased after the stage 4 was loaded. That is what made me contact Malone about it.

I will be lengthening the actuator rod some more today and see what that gives me. If I can't figure it out myself, it'll be going to a TDI guru for its repair!

KERMA · May 9, 2017

the youngest of these BEW cars is 11 years old at this point. It is not uncommon for there to be mechanical or electrical issues that need working out. Stuff just simply wears out after 10+ years of service. The basic engine is stout, but there is always some of the "bolt on" type maintenance stuff that needs attention. The good news is, replacement is an upgrade opportunity!

If this were my tuning job I would be sending the customer a tune that is stock except for the 3bar map sensor. This will facilitate troubleshooting and eliminate the temptation to request endless "retunes" to try and make a broken car work. Then after the mechanical glitch is verified gone, they get the tune for more power. Otherwise it gets ridiculous and quickly out of hand always second guessing the tune. Maybe it "works" but then 6 months later there's that e-mail "remember when you fixed my broken car with a tune? well it's doing it again can we do it again just like before?" You would think that after more than 10 years of tuning BEW it would be figured out by now. So IMO logs are for troubleshooting a broken car, not "dialing" the tune. Maybe for a noob who is learning how to do it, but after a thousand cars and a decade I would think at some point it is not needed any more... especially with proven upgrade combinations.

During an overboost condition, the N75 duty cycle should be actively seeking to lower the boost. (unless it's already at minimum DC of 5% or so, which indicates it "trying hard as it can") Likewise with the opposite condition. When you see that in the logs, then the tune is doing what it is supposed to be doing. If the car doesn't cooperate, then, well, you need to look at why the car isn't complying with what the tune wants it to do. But if the N75 duty cycle doesn't show any attempt at correction, or even worse, doing the opposite, then it's a good bet that the tune needs looking at. You should always see the tune trying to correct a control deviation and trying harder with larger deviations and the longer they go.

If the N75 doesn't change during a control deviation then there may be something called anti-reset windup happening where the DC is frozen. This is entirely within the turbo control scheme of the ECU and there are application switches and constants to determine this behavior. If there was no ARW provision then there could be uncontrolled overboost in a situation where there is significant overshoot during a rapid transient. The flip side is where the boost "hangs" a bit while everything settles out. This is another relatively unknown condition but it is entirely 100% controllable and configurable in the tune. (just not considered or even known by most tuners)

Of course there is more that contributes to boost response than just the N75 duty cycle, but that's the first, basic place to begin troubleshooting. Look and "yep, it's doing what it should, something wrong with the car". Then you look at the fueling injection window and torque structure in groups 1,4,8 for a deeper look. And you can see airflow anomalies in group 3. Lots of the time you can find boost leaks or clogs in group 3, and the group 8 smoke limiter will be overly restrictive or overly liberal for a clogged intake/cat or boost leak respectively. Also can help diagnose a bad cam before the bupping.

Another troubleshooting step should be unplugging the EGR and throttle, to eliminate a possible malfunction in that component as the cause. In some of the EDC16 and newer there's an interesting dependency between the smoke maps, EGR, and the boost that is often overlooked or not commonly known. That's partly why I'm not entirely on board with the whole "dyn" thing, as cool as it sounds to say it in conversation. So as part of troubleshooting, just unplug the egr to eliminate that from the equation. If the problem is fixed, then you know you have to look at the egr valve or throttle.

coolant temp sensors and fuel temp sensors are vital in a BEW. Not infrequent failure point. Can definitely affect turbo control as well.

hope this helps.

vwnathan · May 9, 2017

KERMA said:
the youngest of these BEW cars is 11 years old at this point. It is not uncommon for there to be mechanical or electrical issues that need working out. Stuff just simply wears out after 10+ years of service. The basic engine is stout, but there is always some of the "bolt on" type maintenance stuff that needs attention. The good news is, replacement is an upgrade opportunity!

If this were my tuning job I would be sending the customer a tune that is stock except for the 3bar map sensor. This will facilitate troubleshooting and eliminate the temptation to request endless "retunes" to try and make a broken car work. Then after the mechanical glitch is verified gone, they get the tune for more power. Otherwise it gets ridiculous and quickly out of hand always second guessing the tune. Maybe it "works" but then 6 months later there's that e-mail "remember when you fixed my broken car with a tune? well it's doing it again can we do it again just like before?" You would think that after more than 10 years of tuning BEW it would be figured out by now. So IMO logs are for troubleshooting a broken car, not "dialing" the tune. Maybe for a noob who is learning how to do it, but after a thousand cars and a decade I would think at some point it is not needed any more... especially with proven upgrade combinations.

During an overboost condition, the N75 duty cycle should be actively seeking to lower the boost. (unless it's already at minimum DC of 5% or so, which indicates it "trying hard as it can") Likewise with the opposite condition. When you see that in the logs, then the tune is doing what it is supposed to be doing. If the car doesn't cooperate, then, well, you need to look at why the car isn't complying with what the tune wants it to do. But if the N75 duty cycle doesn't show any attempt at correction, or even worse, doing the opposite, then it's a good bet that the tune needs looking at. You should always see the tune trying to correct a control deviation and trying harder with larger deviations and the longer they go.

If the N75 doesn't change during a control deviation then there may be something called anti-reset windup happening where the DC is frozen. This is entirely within the turbo control scheme of the ECU and there are application switches and constants to determine this behavior. If there was no ARW provision then there could be uncontrolled overboost in a situation where there is significant overshoot during a rapid transient. The flip side is where the boost "hangs" a bit while everything settles out. This is another relatively unknown condition but it is entirely 100% controllable and configurable in the tune. (just not considered or even known by most tuners)

Of course there is more that contributes to boost response than just the N75 duty cycle, but that's the first, basic place to begin troubleshooting. Look and "yep, it's doing what it should, something wrong with the car". Then you look at the fueling injection window and torque structure in groups 1,4,8 for a deeper look. And you can see airflow anomalies in group 3. Lots of the time you can find boost leaks or clogs in group 3, and the group 8 smoke limiter will be overly restrictive or overly liberal for a clogged intake/cat or boost leak respectively. Also can help diagnose a bad cam before the bupping.

Another troubleshooting step should be unplugging the EGR and throttle, to eliminate a possible malfunction in that component as the cause. In some of the EDC16 and newer there's an interesting dependency between the smoke maps, EGR, and the boost that is often overlooked or not commonly known. That's partly why I'm not entirely on board with the whole "dyn" thing, as cool as it sounds to say it in conversation. So as part of troubleshooting, just unplug the egr to eliminate that from the equation. If the problem is fixed, then you know you have to look at the egr valve or throttle.

coolant temp sensors and fuel temp sensors are vital in a BEW. Not infrequent failure point. Can definitely affect turbo control as well.

hope this helps.

KERMA,

Great information! When the spike happens, the N75 attempts to reduce boost but not as much as it should. The duty cycle will reduce down to 30-40% which should be much less? Not sure if the actuator rod length would have a factor on this or not.

As for the EGR, I've already tried a run with the valve unplugged, no change. I did not try the anti shutter valve yet though.

There's no codes for anything. I haven't had a overboost code either, but my boost gauge will read 30-34 PSI on a WOT pull from a stop.

vwnathan · May 9, 2017

Resolved

Welp, after so intense actuator adjusting (at least 4 turns longer from what I already did) and replacing about 60% of the vacuum lines mainly to and from the N75 (ran out of new line) it seems MUCH better. I did't expect to have to adjust a new turbos actuator that much! It hadn't been touch before I got it, still had the yellow paint on the nut/threads. Not sure if Fixmyvw.com even would touch it.
http://malonetuning.com/graph/view?log=190#H8KLCADCnV8SWQIDbcOLw4EORkAMBMOgd8OpecKbcMOxMsKywodFw6NvwoJuwroleMO6HxvDosOgOMOfw4zDlDXCtDI2PBHDtipzTMOgCsOvThxEecKnIzpQwooUDMKyTwvCqcKhCcKuGFY%2Bw7fDuRHCug7Ct8KHQMK5w7%2FDpUsiexVHVX5weXPCmE1SHMOYLsKtwrzDvwM8UsOJw4zCogAAAA%3D%3D
Not sure what starts to happen at 3000 RPM, but that might be normal?
Over-all, I'm happy. As I thought from the beginning, nothing was wrong with the tune. Mark is great at what he does. That's the reason I used him. I've heard nothing but positive vibes about Malone.
Back to the vac lines... the one going to the actuator from the N75 was very soft up top where it juntions behing the anti shudder valve. MAybe it was collapsing under vacuum?
Anyways, i'll finish replacing all the vacuum lines tomorrow and be done.
As for Malone stage 4 with a VNT-17, you'll spin tire in 1st and 2nd

Enabled · May 9, 2017

It looks like that weirdness is the PID controller compensating heavily for too much adjustment. Bring it back a little.

vwnathan · May 25, 2017

It came back!

So it only lasted a few days..

I became stumped. One day I went out and started looking over EVERYTHING. What do I find? The black wire on the engine harness side of the crank sensor is broken off. Must have done it when I replaced the turbo feed line somehow and never noticed! So that explains why the boost increased from the beginning of the turbo install! I'm surprised that the wire being broken off didn't throw a code.

Readjusted the actuator to normal specs and never boosts over 25 on the gauge. Haven't done a log yet, but it's going great!

Overboost Problems BEW VNT17 Malone stage 4

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