possible boost leak/wastegate issue?
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This is a discussion on possible boost leak/wastegate issue? within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I switched to a Carberry rom (speed density) about a month ago, and I'm finally getting my ass around to ...

  1. #1
    Registered User poly_poly-man's Avatar
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    possible boost leak/wastegate issue?

    I switched to a Carberry rom (speed density) about a month ago, and I'm finally getting my ass around to fixing up the tune and everything. The AFR's are... getting there :P

    Anyway, I did some mechanical stuff too at the same time, and I'm pretty sure the issues I'm hitting now are mechanical, so I'm posting here rather than in the tuning forum.

    I've been driving my own little tuning route, that includes a situation where I have to do a 0-60 pull to get onto a highway. Just about every time hitting this spot, something strange happens.

    I pull all the way through first, as close to redline as I care to go, then go for second and get straight on it again. When this happens, often times, I'll be around 4krpm, WOT, and the car makes a strange fluttering noise (sounds like either air or exhaust - kind of like the wastegate, but different enough that I'm not sure it is, pulsating on and off pretty fast), and I won't accelerate much, if at all. If I clutch in, let the rpm drop to idle, then get on it in second again, it takes right off like it should.

    This is the only situation I've seen it in, and it doesn't happen every time (but it does happen most times) - it seems like it happens less often if I give it a tiny bit more time for the rpm to drop before clutching out.

    My WGDC's have been hitting the maximums, and I'm not getting quite the boost that I'm targeting.

    Here's a log of my doing a first gear pull, then dropping into second, hitting the issue, clutching in to drop it down to idle, and getting off the clutch to finish the pull: http://ompldr.org/vZW45Yg/romraiderl...704_112631.csv.

    I'm really not sure what this is at all, my thoughts range from my BPV failing to a boost leak that springs itself wide open occasionally, to the wastegate arm being maladjusted... any ideas on what's wrong with my car?
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    Master Baiter EJ257's Avatar
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    You mention you "did some mechanical stuff too", but don't mention it? C'mon man, you know better than to be vague in a troubleshooting request.

    Upload the log to Google Docs so it opens in a spreadsheet. You're much more likely to get people to read a spreadsheet rather than CSV text.
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    Registered User poly_poly-man's Avatar
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    alright, around the time I was converting to SD, I stuck my TGV's open, and replaced my PCV valve with the IAT sensor - the system now pulls vacuum from the turbo inlet full time. Since then I've also replaced the uppipe.

    The only ****ups I had were a BOV bolt (I stripped the threads, but I think by putting in a new, slightly longer M8x1.25 bolt, it's totally sealed. While it was stripped, that was definitely a boost leak, tho), and something that I only remembered just now - I stripped the head off of one of the two bolts holding the wastegate actuator, and never got around to drilling that out, so that is still held on with one bolt. It seems solid enough, though - I can pull out the wastegate by hand without it flexing at all, and it still lines up right. I really should have fixed this when I had the turbo off, come to think of it.

    Anyway, basically crazy shenanigans, that's why I was so vague. I'd be fine if I knew I had a boost leak or smth, but this strange behavior is driving me crazy.

    https://docs.google.com/spreadsheet/...VB0YXdKUi0wQ1E for those who don't want to just download the thing and throw it in excel/oocalc :P
    My big thread: The Used WRX Buying Checklist - Please Contribute!

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    Master Baiter EJ257's Avatar
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    What's up with lines 18-20? Negative ITT?

    You're running pretty rich in some of the WOT logs (10.3).
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    Registered User Heide264's Avatar
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    Just some food for thought (Haven't gotten to open the log yet)...

    If it's a waste gate issue, it's manifold pressure dependent for the most part. Any time you hit/hold a higher boost, it will either open or stay closed. If you are in first or second gear, your boost may be all over the place. I'd just try a full 0-5krpm WOT pull in fourth gear if you are trying to pinpoint it. If it's waste gate, you'll notice it at peak boost pressures.

    I'm not too familiar with exhaust leaks. I'd expect your AFRs and your ears to turn those up before feeling them. No personal experience with them

    In all fairness, you could just be skirting your waste gate opening or closing. I know I spent a while pinpointing why my target AFRs were all over the place during a WOT pull around 2-3k randomly - it was due to my MAF readings picking up some weird information when the waste gate opened. You may just be feeling the 'lack there of' boost when you say that it isn't feeling as expected early in the RPM range (pre clutch in your case).

    I'd suggest a few 'trials' to help pinpoint it:
    -Take out all wgdc. Get a good few WOT pulls to learn what your car does with just waste gate spring pressure. See if it is in the expected ballpark.
    -If it's acting as expected with just spring tension, I'd lean towards a better boost control method (perhaps the solenoid is leaking - I doubt this), adjusting the actuator arm / spring tension (I believe you can in bugeyes - I can't), or looking into adjusting the restrictor pill.

    I am surprised you never noticed the sound before. Can you look over your map to make sure there are no sudden changes in wgdc? You aren't flat foot shifting or anything (judging off of the 4krpm issue and not 5k+), correct? I will spend some time looking at the logs tomorrow for ya though.

    Why not do more pulls similar to a dyno pull?
    Quote Originally Posted by Trainrex
    He was throwing balloons filled with sulfuric acid and shrapnel at the swat team. They finally had to take him down with rubber bullets.
    2011 STi Build Log
    -Part 1 - Reading, Data Logging, and Analyzing Data
    -Part 2 - Turbocharger 101 & Basic Boost Control
    -Part 3 - EcuFlash, Experimental Defintions, and a Drive By Wire Intro

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    Registered User poly_poly-man's Avatar
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    again, the tune is a WiP - it's only .5 rich, though, if you notice what I'm targetting. I know those areas on the VE map are still higher than they should be, but that's why I was out tuning . Timing is all over the place (only now cleaning up after I freaked out about some false knock)... and soon will be a lot more in order. At least I'm way off the "safe" side of the tune.
    My big thread: The Used WRX Buying Checklist - Please Contribute!

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by poly_poly-man
    again, the tune is a WiP - it's only .5 rich, though, if you notice what I'm targetting. I know those areas on the VE map are still higher than they should be, but that's why I was out tuning . Timing is all over the place (only now cleaning up after I freaked out about some false knock)... and soon will be a lot more in order. At least I'm way off the "safe" side of the tune.
    You should never see negative timing. Too little timing will cause knock. If you notice, as soon as you go negative, you start getting FBKC...

    You're only .5 rich, but 10.8 is conservative enough to begin with. What I/C do you have? 11.1 isn't too aggressive for a stock TMIC, 11.3 isn't too aggressive for a quality aftermarket TMIC.
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    Registered User poly_poly-man's Avatar
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    Quote Originally Posted by Heide264 View Post
    Just some food for thought (Haven't gotten to open the log yet)...

    If it's a waste gate issue, it's manifold pressure dependent for the most part. Any time you hit/hold a higher boost, it will either open or stay closed. If you are in first or second gear, your boost may be all over the place. I'd just try a full 0-5krpm WOT pull in fourth gear if you are trying to pinpoint it. If it's waste gate, you'll notice it at peak boost pressures.

    I'm not too familiar with exhaust leaks. I'd expect your AFRs and your ears to turn those up before feeling them. No personal experience with them

    In all fairness, you could just be skirting your waste gate opening or closing. I know I spent a while pinpointing why my target AFRs were all over the place during a WOT pull around 2-3k randomly - it was due to my MAF readings picking up some weird information when the waste gate opened. You may just be feeling the 'lack there of' boost when you say that it isn't feeling as expected early in the RPM range (pre clutch in your case).

    I'd suggest a few 'trials' to help pinpoint it:
    -Take out all wgdc. Get a good few WOT pulls to learn what your car does with just waste gate spring pressure. See if it is in the expected ballpark.
    -If it's acting as expected with just spring tension, I'd lean towards a better boost control method (perhaps the solenoid is leaking - I doubt this), adjusting the actuator arm / spring tension (I believe you can in bugeyes - I can't), or looking into adjusting the restrictor pill.

    I am surprised you never noticed the sound before. Can you look over your map to make sure there are no sudden changes in wgdc? You aren't flat foot shifting or anything (judging off of the 4krpm issue and not 5k+), correct? I will spend some time looking at the logs tomorrow for ya though.

    Why not do more pulls similar to a dyno pull?
    Doing a few pulls on wastegate pressure might be a good idea, to see what's up.

    This situation comes about most consistently when I let the clutch out for second a little early.

    By the way, I totally omitted this information when I copied the post over from nasioc (although it is in my sig :P) - I have been on the GM BCS for a while - worked great on the old MAF rom, but not so well here.

    My WOT pulls are rich because I'm still using conservative stock rom values for those cells in that range - I'm still working on the tune.

    I may consider preloading the wastegate more than I have already, to nail down whether it's actually wastegate.
    My big thread: The Used WRX Buying Checklist - Please Contribute!

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    Registered User Heide264's Avatar
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    I target 10.0 afr at first to get my MAF scaling close. Better rich than lean.

    I'd go ahead with that wgdc = 0. If nothing else, you learn a lot about your car in my opinion. I do that to start building a wgdc map. Gives me an idea what I want to set as target MAP under 3k and when I want to set my wgdc high to use the 3 port.

    Go ahead and post up the results with a WOT pull. I'll make sure to leave some time to go through it =)
    Quote Originally Posted by Trainrex
    He was throwing balloons filled with sulfuric acid and shrapnel at the swat team. They finally had to take him down with rubber bullets.
    2011 STi Build Log
    -Part 1 - Reading, Data Logging, and Analyzing Data
    -Part 2 - Turbocharger 101 & Basic Boost Control
    -Part 3 - EcuFlash, Experimental Defintions, and a Drive By Wire Intro

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    Registered User poly_poly-man's Avatar
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    gah, I didn't log a WOT pull this go around, I'll try to get that in today.

    I did another log with WGDC capped at 0%, same situation as before - the issue didn't come up (although I am lower on power, obviously) - I don't know if that indicates something in the boost control system, or whether it's just an issue with another part that doesn't show up until higher boosts. My atmospheric pressure is 14.6psi today, so the MAP is seeing right around 7psi boost, exactly as expected (stock td04, stock wastegate actuator, etc.). That's: https://docs.google.com/spreadsheet/...CSExsWUE#gid=0

    I'd consider a problem with my boost targets and WGDC tables (this rom actually has initial WGDC tables, like the 32-bit roms), except that with crazy high WGDC's, I'm not seeing my target boost at all (I target right along 140krpm on the compressor map, so about 18psi peak, tapering down to about 12-13 at redline), and that I copied most of the tables straight out of my MAF rom, where I was hitting my boost targets no problem.

    And yeah, that's exactly my plan with the AFR's - set in safe values, and get the VE maps too reel them into those, then start leaning out my table.

    I'm going to do a few map modifications based on my current spool performance, then try a pull (I'm afraid of cops since my ticket, so it'll most likely be a second-gear pull, unfortunately) with both wgdc=0 and wgdc regular.
    My big thread: The Used WRX Buying Checklist - Please Contribute!

    My current car: 2002 WRB WRX Wagon.
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    Registered User poly_poly-man's Avatar
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    hmm, well I got a chance to log again, and maybe it's not the most terribly useful information (I forgot to turn on wgdc and such again - I really thought I saved it in the logger profile), but it should give some insight into the problem.

    This time, that same pull, the power fell off just slightly before redline, and stayed off for 2nd gear. The only thing I can see in the logs is that I jumped a point or two leaner than I was right at the moment it cut power, but that leanness doesn't really follow through into second.

    Thanks for taking a look: https://docs.google.com/spreadsheet/...TZzcm1WaVVKbUE
    My big thread: The Used WRX Buying Checklist - Please Contribute!

    My current car: 2002 WRB WRX Wagon.
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    Registered User Heide264's Avatar
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    poly - check out this graph of your MAP.

    I am not sure what your target boost is per rpm... but there is definitely a reason it feels like you are losing power. Check out how quickly your boost falls off there.

    I'd log the same thing with overall wgdc - what the car is actually using during the pull. It would also let you know if your car is limiting boost via wgdc controls as well. You are hitting around 14psi peak and holding 7-8psi past 5.5k rpm in this one. It would make sense that you'd hear a louder fluttering sound - your wastegate is letting way more air out past 5k in this first pull.

    Keep in mind, boost control and this stuff is pretty fast moving in 2nd gear.

    I will take a look at just your waste gate spring log shortly.

    Click image for larger version. 

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    Quote Originally Posted by Trainrex
    He was throwing balloons filled with sulfuric acid and shrapnel at the swat team. They finally had to take him down with rubber bullets.
    2011 STi Build Log
    -Part 1 - Reading, Data Logging, and Analyzing Data
    -Part 2 - Turbocharger 101 & Basic Boost Control
    -Part 3 - EcuFlash, Experimental Defintions, and a Drive By Wire Intro

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    Registered User Heide264's Avatar
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    This one right here, I agree, rules out any wastegate arm issues:

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    Something, somewhere, has to be letting pressure from your manifold over to your actuator. I bet your wgdc is being cut back, or the solenoid is leaky.

    I wouldn't expect your turbo to fall off that quickly even if faulty - it'd be a more linear drop off in my opinion.

    If it was a severe boost leak, you wouldn't be able to hit your 28psi peak there in my opinion - I could be wrong on that one.


    Did you say you were running the GS 3-port? If so, try putting the stock one back on with the appropriate tuning and seeing if you experience a similar issue. I have a feeling something in your tune is capping your actual applied wgdc. Perhaps a max table, a per gear compensation table, or any other wgdc compensation tables.

    Does the ROM base wgdc off of RPM vs. throttle position? Is there any per/gear compensations?

    Really gotta log that wgdc along with it... Make sure its pulling duty cycle... Then find out what in the ROM is doing it.
    Quote Originally Posted by Trainrex
    He was throwing balloons filled with sulfuric acid and shrapnel at the swat team. They finally had to take him down with rubber bullets.
    2011 STi Build Log
    -Part 1 - Reading, Data Logging, and Analyzing Data
    -Part 2 - Turbocharger 101 & Basic Boost Control
    -Part 3 - EcuFlash, Experimental Defintions, and a Drive By Wire Intro

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    Registered User poly_poly-man's Avatar
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    First off, my plan is to log this situation again with WGDC and such, and get at least a 2nd gear pull, and a 3rd gear pull if I think I can manage it.

    The carberry rom has an initial wgdc, 3d max wgdc and overall max wgdc table. Last time I logged, I was pinned against the maximums the whole time - I may have to increase them (they do taper off). My target boost also does taper off fairly quickly, but not that quickly I don't think.

    The biggest problem I see is that, when this happens, I can't even really accelerate past 4500rpm or so - I have to clutch in and try again. Bad boost control tables can't cause this alone, I would think, right?

    This issue that I'm seeing is more along the lines of a wall that I hit, rather than badly tuned boost, I would think. At least, I can't imagine anything that would do this in the boost control tables at least.

    I don't have the stock solenoid anymore - it's this or nothing. Also, all of my per-gear tables are disabled for now. I'll post up my rom along with the logs shortly.
    My big thread: The Used WRX Buying Checklist - Please Contribute!

    My current car: 2002 WRB WRX Wagon.
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    Registered User Heide264's Avatar
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    Okay, makes sense.

    Cutting that much boost in that short of an RPM range may very well feel like a wall in my opinion - especially with that peak shortly before hand and questionable timing values (didn't examine them much). When I was trying to control my boost before my ewg, 2-3psi boost spikes felt like my engine was pulling timing afterwards, just to put it in perspective. I've found that when you do pulls frequently to get things dialed in, even a degree or two of timing or one psi can change the feel of the car way more than expected.

    How was the older ROM in terms of wastegate control? You may be using dramatically less duty cycle compared to what you were using not realize it. Any pre-carberry pulls with wgdc to compare it with? With the EWG I am only really using 30-40% at peak boost. Before the EWG I was maxing out the solenoid at parts.
    Quote Originally Posted by Trainrex
    He was throwing balloons filled with sulfuric acid and shrapnel at the swat team. They finally had to take him down with rubber bullets.
    2011 STi Build Log
    -Part 1 - Reading, Data Logging, and Analyzing Data
    -Part 2 - Turbocharger 101 & Basic Boost Control
    -Part 3 - EcuFlash, Experimental Defintions, and a Drive By Wire Intro

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