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Turbo stall,,,, slow down????


wrngwae
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been tuning with Scott, and im having issues with what we determined to be posslible turbo stall or slow down. i can boost to 15 psi or so but as soon as i gat close to 20 boost drops like a brick and i will actually start pullling vac at wot? now i have to let off for about aprox 3-5sec for it to recover than it will boost again. i can let off and right back to wot with no change,,,,, i have to wait it out. i tore the turbo down and there was some blueing on the shaft and the bearings were dark in color from the cooked oil. it has to have been that way when i got it but i polised the shaft and soaked and lightly polished the bearing surface. there is a good oil clearance in it now but do you think it is still the turbo???? i did open my oil resticter to 1/8 to see if it helps,,,,it didnt

 

list of mods....

20 over block

weiscos

new marnel head w 1mm os ss valves

ss log mani

hks 40mm external wg to atmo

holset he341

75lb ingectors

fip intake mani

scotts fip upgrade to control spark

scotts coated bearings

MBC

tep 272 cam at stock deg.

 

i know i have a thread on a rebuild kit for the HE341 and i will rebuild it but is is not leaking at the seals at all...

 

Have a log for anyone interesed in seeing this fenomenon....lol

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At first we thought the overboost protection was kicking in but after looking at a lot of logs and going through the tune file several times it looks like the turbo just stops spinning, then starts again after a bit.

 

Right where the vertical line is you can see the MAP has gone from over 200 KPa to 40 or so (vacuum) even though Tye has the throttle wide open (no one holds a throttle to the floor like Tye). He even pumps the throttle several times, the green line going straight up and down, and the accel enrichment, pulse width and AFR are responding to that but with the MAP in the vacuum he ain't going anywhere.

 

Pay no attention to the VE table, that is not Tye's, I pulled this log up while doing some other work.

 

http://picturehosting.com/images/oblique9881/wierdness.jpg

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Thanks Scott you sir are the man....... im telling you people.... i do believe there is nothing this guy cant fix...... even sent him a burnt up Hot tub controler,,,,,he fixed it lol......
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mine was doing some thing close to that. when i upgraded to the 20g once i hit close to 16psi the WG would push open even with a man boost controller at wot .not sure if that is what u are having trobs with or not mine never ran back to vac the turbo would just stall.it was like it would jam the waste gate open if a sec . once i let off the gas .after a sec it would work again . intill i i ran boost again.but my trobs was a bad WG.
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The question I have is...have you pulled off the turbo and disassembled the housings? It could be that either the compressor or turbine wheels are contacting the compressor or turbine housing at a certain spooled RPM due to imbalance or improper fit. It also sounds like you noticed blueing on the shaft, which is a sign of heat and wear. Could be that the bearing fit is too tight and when the shaft is spinning so fast it heats up and expands and locks up the turbo. Either way....take the turbo off and inspect before it implodes and pieces get sucked into your built engine! Edited by CaliConquestAlex
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i have an external wastegate strait to atmosphere and trust me i can turn the boost down and hear that sucker scream strait pipe sound.... i did tear down the turbo and it looked good other than some bluing of the shaft and cooked oil residue on the bearings. i cleaned it up real good and measured the bearing size, shaft and housing. there should be plenty of heat expansion room with out being too loose. so the "play" in it is very minimal. there is NO rubbing at all on any of the wheels either. im just stumped as to why she is stopping? i know it will boost more. but im wondering if i dont have enough exhaust pressure???? but that just dosent make sense to me....or maybe its choking out,,,,IDK,,, just trying to pick some peoples brains. Edited by wrngwae
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My suggestion is to take the turbo back apart just like everyone else is saying. Something is going very seriously wrong if your getting vacuum at full throttle. It doesn't sound like your taking this seriously enough, yes maybe you did check everything when you put the turbo together but something may have changed. Take the sucker apart and double check everything is how it should be or you may very much regret it.

 

Allen

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Lower the boost and see if that changes, if it doesn't then it might be the wastegate sticking. The diaphragm or oring isn't folding or rolling whatever its supposed to.that's why the motor still revs up just you have no boost.

 

If a turbine shaft stops spinning its like you put a cap on the exhaust, your motor will not continue to run at high rpms,it will not hardly rev up at all but since that wheel is larger it might seem to but your coolant temps and EGTs will spike, the head will quickly swell even more and your headgasket won't like it.

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Thanks Eric For the the map. it dosent really do like in the video you posted. while driving and i hammer it lol....Scott likes how i floor it like no other,lol... the boost seems to climb real nice and smooth until it just fall flat on its face almost as if someone it turning the key off on me. but, it still runs . John, i dont think it is the wastegate. i do not hear it open, just the boost drops like a brick. i have a 40mm external wastegate and it has a very short pipe on it the goes down enough to clear the relay rod, and there is no muffler. when it opens it sounds like a 10hp briggs lawnmower with no exhaust reved to the moon,,,,, so i know when its open. i could test the wastegate separately with my air compressor and my MBC and ease the pressure up to see if its closing or getting slightly stuck while i idle the car? its worth a try to test her out.

 

 

John, im running about 15lbs boost now ant it runs great. the wastegate opens and closes as it should with no hikkups. i can also say this,,,,, it does this more in the first 2 gears, than the last 3. im sure it has c something to do with the quicker spool and load in the higher gears

Edited by wrngwae
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i have a mbc. i have tryed 3 different types and it still does it. Sorry for the late response. i just got off vacation. but i did send the turbo out for a look see. lets see what we come up with for the smoking gun?
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Eric, it looked fine free reving but under load is where she gets the case of the DUH's,,,,,,,,,,,, it would have been nice to see it on a dyno though......but is off and shipped out now.... will see if it does it after its back... Edited by wrngwae
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  • 2 weeks later...
well it came back, all shiney and blue! but the problem remains. any more guesses? im lost here. i have never seen this before. the bearings are good, there is no contact to either the wheel.
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well, while at lunch i did some thinking and im wondering if perhaps,,,,,,,,,,,,, under load my motor rotate too much and kinks an innercooler coupling? so im going to go home and set up a limit chain and see if that helps. the reason im thinking this is that i routed my piping as so to retain the battery in the stock location. i did loose the washer tank but it got relocated. so there are 2 90deg couplers in a tight little area. so im thinking at a load, the motor rocks over, kinking a coupler which sends the intake into a vac the boost is released via the WG, and it stops spooling. with having -22hg of vac on that it will hold it with the butterfly open. once i let off. the motor rocks back down, the butterfly closes allowing the coupler to get to atmosphere at least, than it releases. and i can boost again............just a though?
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