Boost Leak, Wastegate and/or Turbo Failure?

Well, the title pretty much sums it up. The reason I'm having difficulty understanding these logs is due to my inability to meet requested boost spikes; however, the rest of the pull is dead on with a (decreasing n75 duty cycle). Usually a standard boost leak shows a similar psi drop across the spam of the pull (corresponding with an increasing n75 %)...this is not the case here. I have yet to come across any logs that show similar results to mine (anywhere...any engine, any car).

With that said, below are six graphs (logs) from my car over the past 4 weeks. The first two are with the stock DV and APR's sII+ HPFP file, the car is running 100%...




The next two logs are the same file with the EJ DV kit installed (the timing/rail pressure log was to confirm there were no other circumstances affecting the boost pressure). The car was given three days to adapt to the new hardward before logs were taken...




The next log is the same file with the OEM DV reinstalled and the car was given two days to readapt back to the old hardware...



Finally, the last log is with the EJ DV reinstalled and no adaptation was allow...reinstall completed and logs taken immediately upon start-up (this has been by far the best log taken since the issues arose, but it's still not 100%).



My local guy seems to think that it's definitely an issue with the OEM wastegate...possibly some carbon build up. We plan to pressure test the system soon, but I have gone over every inch of the intake tract and there is no blow-by oil traces anywhere and all connections look stout. I have also run the Deviant Speed PCV fix to determine if my PCV was leaking and I noticed zero change via boost gauge (no logs taken). Thanks for any help. :thumbsup:

Hmmm. After looking at the logs I would definitely say you have some sort of boost leak going on there. Most of the logs I have seen of APR have the waste gate pegged(95% max on APR) for only a few hundred RPMs, you are seeing pegged during the span of the run when it is requesting high boost.

The part that worries me is that you meet/exceed requested when the specified boost is lower near redline. If it was something like the PCV i'd think you'd have a consistent PSI drop across the range. THe most likely explanation I could see is that there is some kind of leak you have only above a certain PSI. I think a pressure test is a good idea if you can get it up near 20 PSI. A failing turbo is a possibility, but I feel like people tend to throw that out too often when it can usually be explain more by a failing component like a wastegate that happens to also be replaced when you replace the turbo. Good luck!

jeffc31337 said:

If it was something like the PCV i'd think you'd have a consistent PSI drop across the range. THe most likely explanation I could see is that there is some kind of leak you have only above a certain PSI.

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This is exactly where I'm stuck too. I can't think of what part of the system would only hold 18psi (or approx)? As you mentioned, anything below 18psi, the system meets/exceeds the requested values, thus the n75 % drops rapidly. Can anyone here think of a location that leaks depending on the amount of boost pressure? Could I possibly have an exhaust manifold leak (I have checked the DP gasket and no leaks were present), that would be leaking enough gases so that the hot-side of the compressor wheel can't spin fast enough until there is ample gas flow (ie. above 4k RPM)?

it could be with all this wastegate actuator talk lately that I'm just brainwashed... but...

Doesn't it kind of make sense that at the point where the PEAK boost is attained, the car struggles and absolutely can't do it... however, when it drops to a lower PSI the car seems to be just fine.

Like when the boost is peak, the wastegate actuator is releasing pressure instead of holding it?

I know it could be other things, it especially seems odd that it happened right after the Eurojet DV was installed which makes me think it has nothing to do with the wastegate actuator and is something related to parts installed/changed in the Eurojet DV setup.

Good luck Ryan, I'm very interested to see what the conclusion is here.

HoldDaMayo said:

Like when the boost is peak, the wastegate actuator is releasing pressure instead of holding it?

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Definitely seems that way. Another thing I could think of is a small pinhole type leak in a DV diaphragm(or any other valves in the systerm that uses a diaphragm). At only certain high boost loads do you get enough deflection for it to lose integrity.

Would it be possible that relocating the DV away from the turbo is buffering it slighly away from pressure changes in the boost systerm and making it hold slightly better?

Pressure test first, that will eliminate a lot of if's. Given the series of events, it seems difficult to blame the WG or turbo itself.

Have you disassembled the EJ DV, cleaned, inspected and lubed it? The problem almost sounds like a sticking mechanical DV - it leaks at low boost, until some PSI starts to help the DV spring close the piston and seal it off. Does that make sense? Could just need a little alcohol swab and regrease.

Chris

doctorgonzo said:

Pressure test first, that will eliminate a lot of if's. Given the series of events, it seems difficult to blame the WG or turbo itself.

I think that's where I'm gonna have to head before I begin replacing things. I do agree it would have to be one hell of a coincedence if the WG/Turbo failed immediately following...but stranger things have happened.

Have you disassembled the EJ DV, cleaned, inspected and lubed it? The problem almost sounds like a sticking mechanical DV - it leaks at low boost, until some PSI starts to help the DV spring close the piston and seal it off. Does that make sense? Could just need a little alcohol swab and regrease.

I have dissassembled and regreased the DV twice now. That was my initial thought process as well; however, once I put the stock DV back on and the issue was still present (see graph 5 labeled OEM DV), I ruled this out as a possibility.

Chris

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Answers in bold :thumbsup:

I'm basing this assumption purely on the results seen from the testing of our actuator, but the N75 duty cycle being pegged over 90% for almost the entire time that actual boost is NOT meeting requested might be indicating a wastegate issue, meaning an exhaust gas leak from exhaust gas pressure blowing open the flapper on spool up.

This is assuming we have completely ruled out a leak on the boost pressure side first via a pressure test.

The reason I suggest this is because our results have shown an immediate decrease in N75 duty cycle throughout the entire RPM band more or less, while simultaneously achieving an increase in actual boost compared to requested.

This is not a sales pitch, by any stretch, so I'm sorry if this comes across as such, but it seems blatantly obvious to me, based on the N75 duty cycle coming down and actual boost going up, which is the desired result in this case, right?

Sooooo if there is no boost leak leak, you should tighten the wastegate tension adjustment on the stock actuator until the curve looks right.

Doesn't make sense that the WG would work fine before the DV install, but be blowing open now, unless you installed a catless exhaust, or something like that at the same time.

OP, did you have a different aftermarket intake or DV relocate on before the EJ setup went on? Changed MAF housings?

F/I is still a black art to me but I'd say:

1. check for a boost leak
2. pull off and inspect the discharge pipe and inspect intake side of the turbo. Also, when you are looking at the intake side check your N75 hoses for tears or kinks.
3. pull off the DP flange and inspect the exhaust side of the turbo

Good luck!

Did you change your TB pipe when you installed the EJ DV? I'm going with a boost leak somewhere between IC outlet & throttle-body.

Mike@Forge said:

I'm basing this assumption purely on the results seen from the testing of our actuator, but the N75 duty cycle being pegged over 90% for almost the entire time that actual boost is NOT meeting requested might be indicating a wastegate issue, meaning an exhaust gas leak from exhaust gas pressure blowing open the flapper on spool up.

This is assuming we have completely ruled out a leak on the boost pressure side first via a pressure test.

The reason I suggest this is because our results have shown an immediate decrease in N75 duty cycle throughout the entire RPM band more or less, while simultaneously achieving an increase in actual boost compared to requested.

This is not a sales pitch, by any stretch, so I'm sorry if this comes across as such, but it seems blatantly obvious to me, based on the N75 duty cycle coming down and actual boost going up, which is the desired result in this case, right?

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This is exactly what my local guy is telling me. Again, I will need to perform a pressure test, just to rule out a leak in the intake track, but this is where I'm leaning towards. Obviously, with you guys releasing an upgraded WG, I will be following any results with regards to APR software. :thumbsup:

doctorgonzo said:

Sooooo if there is no boost leak leak, you should tighten the wastegate tension adjustment on the stock actuator until the curve looks right.

Doesn't make sense that the WG would work fine before the DV install, but be blowing open now, unless you installed a catless exhaust, or something like that at the same time.

OP, did you have a different aftermarket intake or DV relocate on before the EJ setup went on? Changed MAF housings?

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Nope...same intake, just went from stock to EJ DV (and then back to stock, and back to EJ DV). I completely agree with you that it would have to be pure coincedence for the WG to fail at the same time, but then again, there are other areas I need to check out first...hopefully have a full pressure test done this weekend.

junker said:

F/I is still a black art to me but I'd say:

1. check for a boost leak
2. pull off and inspect the discharge pipe and inspect intake side of the turbo. Also, when you are looking at the intake side check your N75 hoses for tears or kinks.
3. pull off the DP flange and inspect the exhaust side of the turbo

Good luck!

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Yeah...definitely doing number one soon, maybe number two as well, but number three is a real PITA...not saying that I'm against it...I'm just hoping it doesn't come to that. :wink:

SDM said:

Did you change your TB pipe when you installed the EJ DV? I'm going with a boost leak somewhere between IC outlet & throttle-body.

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I did this as well and this was initially my thought process as well. Even replaced one of the hoses on the kit as well. Been reinstalled twice now and still similar results.



Thanks for everyone's help thus far. I plan to get under the car this weekend and hopefully run a pressure test as well. I will keep this thread updated as I go along. :thumbsup:

I forgot to mention I'm pretty sure your problem is your dbilas intake -- take it off and I will dispose of it for you

Update:

Pressure tested the intake track, found one leak at my NS boost gauge tap...moved gauge tap over to my BSH tap. Pressure tested again, all I could hear was the crankcase pressure releasing through the oil cap...I'm assuming no more leaks (tested at 18-20psi). Just went for a quick test drive...boost maxes at 18psi in 3rd gear pulls according to my gauge (didn't have time to log). Thoughts?

Do you see much for CF's when logging your timing? Looking at the logs of the timing graphs the timing advance lines arent smooth at all. I've found that every portion of the line with a negative slope is a result from the ecu pulling timing.

Has anyone out there tried replacing the n75 valve?? Is there any chance all this crap from the PCV system is being pulled into the n75 and clogging it up?