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Help the 17 year old Please asap races are saturda

This is a discussion on Help the 17 year old Please asap races are saturda within the Forced Induction forums, part of the LSx Technical Help Section category; ok well i got my rear mount put back togetheri had it on th lift and put it in 1st ...

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    Help the 17 year old Please asap races are saturda

    ok well i got my rear mount put back togetheri had it on th lift and put it in 1st (A4) and held te brakes and hit the gas ....help it at 3500 for a sec then slowly went up to red line then let off BOV can on somewhat i think AND THE CAR ALMOST DIES....but n boost and i dont think it even hit the 0 mark.......so i took it off the lift and tried to do a burno out and it wouldnt even break the tires loose......so i re ran my refrence line for the waste gate it is on the compressor of the turbo and also the T for the gauge and BOV on my brake booster... so i took it back of the lift and took it to the street irode first gear till about 6500 and let it shift still no boost and same in secound gear but i put it back it first and punched it then let off and the BOV psst but no boost ...well i rode around for a while after checking stuff again and thn whnen i punched it it started smoking out of the exhaust side of the turbo (has no pipe just the turbo) so i checked for leaks and no oil leaks i think it is oil going into the hot side of the turbo it looks like it shot oil out of the exhaust side or "is" shooting ...the waste gate is set at 7psi open atmoshpere on the exhaust part and it is a greddy adjustable BOV the turbo is a 50a.r/84a.r the return line to the pump and engine is 3/8 line..the maf sensor is on the intake side of the turbo right after the cone filter...

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    let the F-Bodies roll jimmybling31's Avatar
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    sounds like not big enough of a turbo to me. or it's too big. I don't know that much about turbo's but i know that if it's like that it's either too big or too small

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    Senior Member Rhinohuey's Avatar
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    Quote Originally Posted by jimmybling31 View Post
    sounds like not big enough of a turbo to me. or it's too big. I don't know that much about turbo's but i know that if it's like that it's either too big or too small
    Even if the turbo is too big or small, it should still make some boost at any throttle at all I would think.

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    Quote Originally Posted by Rhinohuey View Post
    Even if the turbo is too big or small, it should still make some boost at any throttle at all I would think.
    no you should have vaccum for some of the throttle.
    did you say your exhaust ends right after the turbo?
    you need some back presure for the turbo to spool.
    i would check in to that to start.

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    No the turbo spins off the exhaust coming out of the motor... I have seen tons of people running straight exhaust no mufflers no cats....

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    ruby red
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    sorry I didnt ask correct so you have a rear mount turbo correct?
    after the exhuast goes threw the hot side of the turbo the exhaust ends?
    i think it needs some back pressure on the turbo for to work correct.

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    No the exhaust spins the propeller, then comes out the side of the exhaust side of the turbo if that made any since...

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    let the F-Bodies roll jimmybling31's Avatar
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    why don't you try running without a bov and see what happens. Just and idea...don't flame me. also check your line for leaks... again don't flame. I'm just thinking it might identify the problem. if there is a problem with the bov that makes it not close all the way it might cause the boost to not go up and it just stay at atmosphere. it would also allow for there to be more vacuum when not in the throttle... just a though.

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    ruby red
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    Oh I was confused sorry. mybad. Is all your charge piping leak free, im sure you checked. Have you checked your waste gate and/or wastegate acuator if your not sure just pull the vaccum/boost like to the acuator off and see if it boost this will test the waist gate. Becarfull not to boost to high.

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    Jimmy is right...If your bov is staying open you wont have any boost... Does it make the phsssssssssssssssss sound all the time when you rev up?

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    ruby red
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    the blow off valve would only leak if there was boost. unless its a cheap one that got cloged open some how to let there be a huge vaccum leak down pipe form the mass air flow sensor...you could check there i suppose

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    Senior Member Rhinohuey's Avatar
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    Quote Originally Posted by 01TransAm5.7 View Post
    no you should have vaccum for some of the throttle.
    Yeah I understand that, but any turbo car I've seen will always immediately start making boost (after a short period of making vacuum) after having the throttle down for any time at all....as long as the turbo is making any boost at all. From what I've experienced, if the engine is not getting any boost there is a problem with the wastegate or BOV or something. The turbo itself is not very complicated...as long as its spinning freely, it is pressurizing the air and sending it back to the front of the car.

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    let the F-Bodies roll jimmybling31's Avatar
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    Quote Originally Posted by Rhinohuey View Post
    Yeah I understand that, but any turbo car I've seen will always immediately start making boost (after a short period of making vacuum) after having the throttle down for any time at all....as long as the turbo is making any boost at all. From what I've experienced, if the engine is not getting any boost there is a problem with the wastegate or BOV or something. The turbo itself is not very complicated...as long as its spinning freely, it is pressurizing the air and sending it back to the front of the car.
    I don't understand how the wastegate works really. could you explain and I might can be a little more help in the matter and it might explain the problem to the poster.

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    Senior Member Rhinohuey's Avatar
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    Quote Originally Posted by jimmybling31 View Post
    I don't understand how the wastegate works really. could you explain and I might can be a little more help in the matter and it might explain the problem to the poster.
    I'm not exacty sure on HOW they work, but I'll tell you what I understand.
    Wastegate redirects exhaust gas out but NOT towards the turbo once full boost is reached so that it stops making excess boost. Wastegate is typically electronically calibrated and actuated by a spring. (I think that the wastegate is the problem...maybe an electronic problem or something wrong with the valve itself.)
    Blow off valve just opens up to prevent boost surge on the boosted side of the turbo into the intake manifold. A BOV is operated just by a spring usually.

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    let the F-Bodies roll jimmybling31's Avatar
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    Quote Originally Posted by Rhinohuey View Post
    I'm not exacty sure on HOW they work, but I'll tell you what I understand.
    Wastegate redirects exhaust gas out but NOT towards the turbo once full boost is reached so that it stops making excess boost. Wastegate is typically electronically calibrated and actuated by a spring. (I think that the wastegate is the problem...maybe an electronic problem or something wrong with the valve itself.)
    Blow off valve just opens up to prevent boost surge on the boosted side of the turbo into the intake manifold. A BOV is operated just by a spring usually.
    I don't know wastegates well but on bov I know alot of them work off of vacuum. (i was reading into dsm's for a while and learned tons about the parts I was gonna change)

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    The waist gate AND blow off valve are vaccum/boost actuated both should be closed with vaccum and at a set psi of boost the waist gate should open releasing exhaust befor it gets to the turbo, the blow off valve should hold boost on the charge pipe side till you close the throttle making more vaccum on one side of the blow off valve causing most of the presurized air excape from the charge piping hence pisssss or woosh depending on model.

    also check and make sure there are no leaks from the mass air flow sensor to the turbo either getting more air then read causing air fule mixture to be lean. or less cuasing a/f to be ritch

    Quote Originally Posted by Rhinohuey View Post
    Yeah I understand that, but any turbo car I've seen will always immediately start making boost (after a short period of making vacuum) after having the throttle down for any time at all....as long as the turbo is making any boost at all. From what I've experienced, if the engine is not getting any boost there is a problem with the wastegate or BOV or something. The turbo itself is not very complicated...as long as its spinning freely, it is pressurizing the air and sending it back to the front of the car.
    not true for most cars unless you are talking about when the car is roling and there is a load on the engine. but stoped with no load you cant build much boost. you can get it to blow off stoped but it wont be a lot of boost. even with a load you could probably get in to it 25% throttle with no boost. unless the car has anti-lag of course
    Last edited by 01TransAm5.7; 03-15-2008 at 08:04 AM.

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    Since you have the exhaust off check and see if the turbine is spinning....

    Take it to someone who can do a leak down test for boost....

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    let the F-Bodies roll jimmybling31's Avatar
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    ok. this has had me puzzed for so long and I couldn't figure it out. I'd have to see it though, but I think alot of the problem is the placements of the maf. think about it. there is a ton of charge tubing it has to fill before it forces the air into the motor and because the turbo is in the back it also takes longer for the exhaust to build up enough to build boost there. so you have huge turbo lag that is not accounted for in the programming. you need to have the lag calibrated in the maf to the throttle body. a really good tuner could do it. that's why when you floor it it won't spin the tires. right when you floor it it's not thinking it has much air flow. without being tuned for the maf being where it is you will not produce power at all with that setup. in theory it works but the tuning has to be correct to. the sts setup has 100% efficiency so they can leave the maf where it is. also part of the sts setup is a tune if you go for the high end setup and that setup can produce some mad power. sometimes in excess of 450hp on a stock car

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    Missing 4 Cylinders BULLET_WS6's Avatar
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    it sounds to me like the only logical explanation is in the wastegate,
    backpressure cannot be the problem as most of the rear mounts do not have exhaust after the turbo and not to mention that would mainly cause lag and it would eventually spool, cannot be the maf if the car is still running up to high rpm it is releasing a bunch of air(exhaust) to spin the turbine.
    the wastegate is probably actuating way to early... also possible you have an exhaust leak? buti doubt it... would have to be big... like... an open cutout? now wouldnt that be funny if that was your problem?

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    let the F-Bodies roll jimmybling31's Avatar
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    Quote Originally Posted by BULLET_WS6 View Post
    it sounds to me like the only logical explanation is in the wastegate,
    backpressure cannot be the problem as most of the rear mounts do not have exhaust after the turbo and not to mention that would mainly cause lag and it would eventually spool, cannot be the maf if the car is still running up to high rpm it is releasing a bunch of air(exhaust) to spin the turbine.
    the wastegate is probably actuating way to early... also possible you have an exhaust leak? buti doubt it... would have to be big... like... an open cutout? now wouldnt that be funny if that was your problem?
    it would still go up to higher rpm's if it were the maf. the tps is reading more throttle, and the throttle body is allowing more to go in. the computer is getting confused immensely. think about it. if the turbo is has enough lag like it would in that setup then it would do that.

    take it to a performance shop and get them to look at it. I can almost say without a doubt that a good performance shop that does GOOD tunes will be able to figure it out. also call up sts and talk to them. they might be supportive if you get a nice guy on the line. if not they will turn you down, but what do you have to lose. that is a pretty weird problem that sts prolly had to go through

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