Cant hit boost target

[arnold600]

I dont believe i have any leaks but i could be wrong. Unplugged the vacuum hose from ecbs and wastegate and hit 22lbs and immediately let off. so i dont think i have any hose leaks. i have a few 3rd gear data logs attached. maybe someone can see if anything fishy is going on. only seem to hit between 11-13psi. Also, APP data says 100% throttle opening yet TPS data says only around 70% is this normal?

[Carskick]

Based on the logs, I'm guessing you are mostly stock? Mods/Tune? Also, is this a MS6 like in your avatar?

Throttle position appears mostly normal, which usually holds at 76-77 at WOT. yours starts at 71 but still gets to 76-77.

[arnold600]

Originally Posted by Carskick Based on the logs, I'm guessing you are mostly stock? Mods/Tune? Also, is this a MS6 like in your avatar? Throttle position appears mostly normal, which usually holds at 76-77 at WOT. yours starts at 71 but still gets to 76-77.

Yes. Same one in avatar. just intake, TIP, bov, axleback and test pipe. Cobb apv3 on stage 1 ots tune

[Fstrnyou]

The only tune related things to limit boost are throttle and wastegate. The throttle has been ruled out as the problem, so let's look at the wastegate side of things.

You know you can boost plenty if you remove boost signal to wastegate via your sketchy test. And with it hooked up, your boosting near spring pressure. So, your WGDC must be very low or maybe your EBCS is not functioning properly. It could be stuck closed. Or maybe you have an electrical issue between your ECU and the EBCS.

[arnold600]

Originally Posted by Fstrnyou The only tune related things to limit boost are throttle and wastegate. The throttle has been ruled out as the problem, so let's look at the wastegate side of things. You know you can boost plenty if you remove boost signal to wastegate via your sketchy test. And with it hooked up, your boosting near spring pressure. So, your WGDC must be very low or maybe your EBCS is not functioning properly. It could be stuck closed. Or maybe you have an electrical issue between your ECU and the EBCS.

I put a new oem ecbs in and no change. Should i do a manual controller?

[Fstrnyou]

No

[arnold600]

Originally Posted by Fstrnyou No

What else would you reccomend? I mean. I reinstalled my tune, ecbs is new, i just smoked my system and no boost leaks. What else could it be?

[Fstrnyou]

I mentioned 3 possible sources of the issue. You only addressed 1 of them.

Also, since your tune is OTS, I'm assuming it's a load tune, not a boost tune. Have you verified whether or not you are achieving load targets?

[arnold600]

Originally Posted by Fstrnyou I mentioned 3 possible sources of the issue. You only addressed 1 of them. Also, since your tune is OTS, I'm assuming it's a load tune, not a boost tune. Have you verified whether or not you are achieving load targets?

How would i change WGDC? Im gunna have to do a few more logs with more data so you can check. And throttle seems normal? I tried changing the wgdc on the cobb but it literally doesnt change a thing. Wasnt sure if you needed an aftermarket 3 port ecbs or not. Upped the wgdc to +5% and no change

[tegxsi]

OTS maps are boost tunes. They are up to V2.60 on the MS6 Cobb OTS maps. Maybe you can give that a shot.

Usually when you have a test pipe you would go with a stage 2 map but may not help in this situation since stage 2 WGDC are lower than stage 1.

[arnold600]

Originally Posted by tegxsi OTS maps are boost tunes. They are up to V2.60 on the MS6 Cobb OTS maps. Maybe you can give that a shot. Usually when you have a test pipe you would go with a stage 2 map but may not help in this situation since stage 2 WGDC are lower than stage 1.

My maps are all up to date from Cobb. I have new ECBS, I smoked the system, Adjusting WGDC % through the cobb has no effect. Still at around 12.4psi. I even put my oem recirc valve back on, thought maybe the Turbosmart BOV was faulty. still no change. Even tried stage 0 tune, no change, all my connections are tight. no boost leaks. Its been driving me nuts for the past 6 months.

[aeonpsych]

I'm in a similar situation (although I am mostly stock with no tune/tuner, just a data logger)...

I am only getting between 8-12 psi (12 is usually with a spike), it usually hovers right around 8-10. I've pulled apart the tip, plastic intake tubing, the top mount intercooler, both elbows for the intercooler, and the bov at least 4 times. Sprayed engine starter fluid around all vacuum lines, and nothing. Cleaned MAF multiple times, and checked ebcs, still no improvement. Regapped spark plugs to like 22 and felt a little improvement in throttle response, but not boost pressure.

Last thing I can do is check for leaks with a leak detector. Just need to build a custom pipe setup for it.

Friend thinks my cat is clogged or faulty oem bov, but idk.

[arnold600]

Originally Posted by aeonpsych I'm in a similar situation (although I am mostly stock with no tune/tuner, just a data logger)... I am only getting between 8-12 psi (12 is usually with a spike), it usually hovers right around 8-10. I've pulled apart the tip, plastic intake tubing, the top mount intercooler, both elbows for the intercooler, and the bov at least 4 times. Sprayed engine starter fluid around all vacuum lines, and nothing. Cleaned MAF multiple times, and checked ebcs, still no improvement. Regapped spark plugs to like 22 and felt a little improvement in throttle response, but not boost pressure. Last thing I can do is check for leaks with a leak detector. Just need to build a custom pipe setup for it. Friend thinks my cat is clogged or faulty oem bov, but idk.

I thought possibly my turbosmart bov was faulty, switched to my oem and no change. Not sure what it could be. Im clueless honestly.

[Jeff23spl]

Some car may just not boost the same with similar wastegate duty, there could be some mods or mechanical work that change parameters etc.
But your a bit tied up with just ots maps too...
I never try the WG duty update functions of the cobb but it could be easy to check if it works. You put it a 0 and log. Change it for +10% and log again under same conditions to check if the commanded wastegate duty have changed in the log. If it does as it should but the boost doesn't increase, you have something wrong mechanically.
If the WG duty doesn't change, it is because the feature isn't working...You can check with cobb for it.

You said you checked it but for the wastegate, if you just replaced the ebcs you may have miss anything pipe related. etc

IMO for leaks the only thing that really works is a boost tester at the place of the filter. I wrench on a speed for the last 10 years, i know how to connect piping properly and i hate to do something twice but sometimes i have to. Pipe with a colar end are hard to seal. And a lot of thing could leak too. PRessure test will check everything. any other tests will just check what you suspect that could leak and you may miss one...

I had some overboost problems with my 6 . i got access to ATR (Again) and finaly ended by installing a 3ports EBCS and a special tune to fix the issue untill i get time and money to swap engine and turbo on a solid base. I know some may be just looking for little more but there is no miracles, either you go full retard or you live with what you got from an unknown used car...

[arnold600]

UPDATE. So yesterday i put the stage 0 tune on, and if i mash the gas mad hard and like rock the pedal i got it to 15psi once under high load. (stock tune must be load tune) going up a hill. and pretty consistently 13.5psi on flat ground. Maybe i have a gunked up throttle plate????? also, dont worry, the floor mat is out of the way.

[Fstrnyou]

Log APP as well as TPS.

[arnold600]

Originally Posted by Fstrnyou Log APP as well as TPS.

in my logs up top it has some tps data. says around 71-76% tps where app data is 100% ill do a log later today.

[Fstrnyou]

Ah okay, I missed that. Nevermind then.

[arnold600]

So i cleaned out the throttle body. Same result, only make 11-12psi on stage1 93 +sf and make 13-15psi on stage 0 tune. Only for a brief moment, holds steady 13. So maybe i should call cobb or get the accesstuner software so i can dive a bit deeper into this issue.

[MSMS3]

There are so many little things that can cause the low boost in relation to expected target. One sometimes overlooked is the small hoses/ lines to and from the ECBS.

They get hard, brittle and crack over time. It is hard to detect the splits.

Replacement hose is cheap. Sold by the foot at autoparts stores.

Even if it does not restore boost, it probably should be done. Give it a try while you are at it.

[arnold600]

Originally Posted by MSMS3 There are so many little things that can cause the low boost in relation to expected target. One sometimes overlooked is the small hoses/ lines to and from the ECBS. They get hard, brittle and crack over time. It is hard to detect the splits. Replacement hose is cheap. Sold by the foot at autoparts stores. Even if it does not restore boost, it probably should be done. Give it a try while you are at it.

Yeah I bought some new hose from napa and replaced them. Nothing changed sadly.

[Solarsurge]

I had a similar thing happen to me when I increased boost once. Turned out that the higher boost pressure blew the cap wide open on the PCV vacuum port on the back of the intake manifold. I had it capped for my OCC routing, but there's usually a hose there that goes to the PCV valve. Might want to check that out.

[arnold600]

Originally Posted by Solarsurge I had a similar thing happen to me when I increased boost once. Turned out that the higher boost pressure blew the cap wide open on the PCV vacuum port on the back of the intake manifold. I had it capped for my OCC routing, but there's usually a hose there that goes to the PCV valve. Might want to check that out.

I smoked the system and no leaks sadly. On stage 0 tune i hit 15 psi peak and maintain 13.5 ish. stage 1+sf ots cobb tune i peak 13 and maintain 11.5-12psi

[MSMS3]

Originally Posted by arnold600 I smoked the system and no leaks sadly. On stage 0 tune i hit 15 psi peak and maintain 13.5 ish. stage 1+sf ots cobb tune i peak 13 and maintain 11.5-12psi

As you are now, what is your wastegate duty cycle under max load?

The other guy with somewhat similar issue, @aeonpsych; has a WDC close to 90% trying to hit his boost target and falling short.

We are now starting to think he may have a restriction on the exhaust side (perhaps a clogged primary cat), since he, like you, seems to have eliminated most intake side sources for the problem. His wastegate is staying closed, trying to build boost, but not able to pass any higher rate of exhaust flow. That suggests a blockage. While not definitive until he can check that (not so easily done, as he has to remove the downpipe with primary cat included to check), we can't tell for sure. He could still have a big boost leak, but that seems to have been excluded.

[arnold600]

Originally Posted by MSMS3 As you are now, what is your wastegate duty cycle under max load? The other guy with somewhat similar issue, @aeonpsych; has a WDC close to 90% trying to hit his boost target and falling short. We are now starting to think he may have a restriction on the exhaust side (perhaps a clogged primary cat), since he, like you, seems to have eliminated most intake side sources for the problem. His wastegate is staying closed, trying to build boost, but not able to pass any higher rate of exhaust flow. That suggests a blockage. While not definitive until he can check that (not so easily done, as he has to remove the downpipe with primary cat included to check), we can't tell for sure. He could still have a big boost leak, but that seems to have been excluded.

Could be possible. My WGDC @ 5600rpm is 58%

[aeonpsych]

Just to check in since my similar issue was mentioned here, so far I've narrowed it down to either a faulty/leaky BPV, or exhaust restriction.

Turbo shaft has minimal play, no oil or fluids were present in the turbo housing, and the wheel spun as it should. Checked many many times throughout the lines for leaks, but have not done a pressure leak or smoke test. I haven't been able to have time to get the parts to make an adapter. Have a brand new bcs installed as well, which had no effect on the issue.


After this past weekend, did another visual inspection on the lines, re-cleaned MAF, and replace the spark plugs. Car is now able to hold around 10 psi in all gears, peaking at 14 ish in 4th, but quickly tapering down to 10. Friend that was helping me check it this past weekend thinks it is either bpv or exh related.

Symptoms before this past weekend was no more than 8 psi all gears, unless I disconnected the vac line from bcs to wg. Then I would get around 12 in 1-3 gear and 15-20 in 4-5, did not try 6th. I would get a lot of stumbling at both both 12 psi and 15 psi depending on the gear, and if kept on it long enough, would get CEL for cylinder 4 misfire and overboost. I was able to consistently hold boost levels at these levels by just easing in on the throttle (what I was doing to try and get it to throw a CEL in the first place). This leads me to believe there is not a major leak preventing boost from at least hitting proper levels in the first place, which I haven't been able to do.
Oddly cyl 1 plug was the worse looking of the 4, where it was completely dry black. The other 3 were just a tad on the white side.




Long story short, still trying to narrow down the issue, but believe it to be leaky bpv or exh restriction. Both me and my friend are leaning towards exhaust restriction, as I had symptoms of a failed cat a year ago. The rotten egg smell, and also a rattling noise (which I thought to be suspension related), but my friend demonstrated a failed cat he had in his garage that made a very similar noise. I currently don't have the rotten egg smell, but do have the rattling noise. We also think my car is not as loud as it should be (I have a straight pipe from the primary cat back. No resonator or 2nd cat, or muffler, which is leaning us towards a clog in the exh.

But yea, we both looked at where the dp/cat is and how the cat back pipe is welded up, and it's going to be a pain to get that out. Also, if it's being deleted (my preference, especially while it's out), I would prefer to have the hpfp internals at the minimum, so this check is really being held off.

[Jeff23spl]

Bright, the boost season, no cat and no hpfp isn't a good idea.

the first one is a pita to remove but you may just disconnect the flange where the second cat usually connect to inspect the primary with a test light....
btw, rotten eggs smell isn't a perfect proof of a plugged cat, some brand new may smell just because of fuel or a car that remain granny driven and then pushed a bit more...

It could be that, blocking in or out of the engine will prevent the turbo from making good boost...i dont keep cat long enough to test but my sister burned is honda with a plugged one, the valves overlap phase of the engine made it eat some part of the cat internal...