no boost? what going on

[nismo1003]

i started it up today, I rev it to 3000-4000rpm , i dont' see any boost at my boost gauge only vaccum at 20 (i tried to relocated the vaccmum/boost source from else where). it keep backfire because it runs too rich 370cc (E-manage control) and a FMU as I rev higher. so I look inside of the compressor side(turbo) found out that it doesn't want to spin at idle(sometime it stop) , It would just spin when i rev it? is it normal? or it should be move freely even at low RPM(idle)? I bought this turbo off Ebay , it is a T3 off from a 300ZX , I purchased one of those turbo rebuild kit. can i do it myself? or i should take it to the shop? I heard if i do it i will mess up the aligment? how much I will spend on rebuild if I take it to the shop?

[andrave]

you can probably do it yourself, not sure about the alignment. One of my friend's dads (family of 6) owns a few volvos and he rebuilds the T3's off them in his garage, so I'm guessing it isn't that hard.

I don't know about the compressor spinning at idle, I don't actually own a turbo...

I do have a question, why are you running FMU and e manage? I thought emanage didn't require an FMU... maybe thats why you are running rich?

[nismo1003]

yeah I just realize that I dont' need a FMU, but I installed it and I will lean it out from the e-manage later. or I just take it off.

[nismo1003]

do i need any speical tools to take it off beside wrench ? is there any retainer clip? I heard I should mark off some stuff? whoever did a rebuild or know about it. please give me some advice ?

[WDRacing]

Lose the FMU....The turbo doesn't spin at idle. No problem exists. You won't actually see boost on the boost gauge unless you are actually driving the car or have a load on the engine.

WD

[WAbernethy]

The turbo doesn't spin at idle.

WD

Don't be so sure. I was screwing with mine the other day and bypassed the compressor side of the turbo so that I could see the blades turning. Even with no load the blades were spinning. It was fun, i revved it up a bit and felt the nice warm breeze coming out of the outlet. I let it idle for a few minutes and turned the car off. It was still turning for about 10 seconds with the car off. No wonder these things get worn out.

[nismoplsr]

its prolly just depends on your idle speed

but even at idle if it is spinning slightly you should be able to grab it and hold it with your hands and it will stop

[nismo1003]

but I revn it , the BOV doesn't open neither( at 3000rpm, too scare to run any higher) , the source is the same as the gauges from the manfiold ? is it also normal? how can i test if the turbo is spinning ok?

[nismo1003]

yes it actually spin a little bit, but not alot and it stop sometime...

[nismo1003]

It is still on the jack... shoudl I take it out and test drive it, it got 1/4 of the 87 octane in my car ,I will go to the near gas station and fill up some 92 , I think I was too worried. I kind of relief a little after I read all this. thanx

[WAbernethy]

It will not build any pressure until you put a load on the engine. I've pulled the e-brake and let the clutch out enough to grab a little and forced it to build slightly but you should prolly just drive it around the block.

[andrave]

at idle I'm thinking the engine is at a vacuum, so the exhaust is flowing out and trying to spin it, but the vaccuum is pulling air through the opposite direction, so if it didn't spin I'd think that would make sense.. is that about right?

[95_240sx]

Your turbo should and will spin at idle if it is working right, ive never heard of one not spinning unless its messed up.

Rick

[WAbernethy]

at idle I'm thinking the engine is at a vacuum, so the exhaust is flowing out and trying to spin it, but the vaccuum is pulling air through the opposite direction, so if it didn't spin I'd think that would make sense.. is that about right?

It's not in the opposite direction. Exhaust flows out and spins the turbine/shaft in direction x. On the opposite end of the shaft, the compressor also spins in direction x, pushing air into the motor.

If what you were syaing was true, as the turbo sped up wouldn't it suck the air right out of the motor? :doh

[andrave]

youre right, I was looking for a possible explanation...even a dumb one.lol

[voddka]

My car had the exact same thing, right after I noticed some shaftplay. I talked to people, and did some research, turbo was gone. A 300zx t3 turbo is a pretty good one, so you should just rebuild it (professional is always a good way to go, but if you feel competent doing it yourself, so be it)

[:: orion ::]

Yeah, guys...any turbo should spin at idle.

If the center section is in good shape, any slight amount of exhaust gas will force the turbine wheel to move, which will make the compressor spin.

If your turbo doesn't move at idle, even if your idle is 400rpm, YOU NEED TO REBUILD IT.

Later - Brian

[WDRacing]

Sorry for the quick post above, I didn't explain myself thoroughly. By saying the turbo doesn't spin at idle, I meant the turbo won't spin enough to indicate a positive pressure on the boost gauge at idle or without a load on the engine.

If you can take your finger and spin the compressor side and it free spins you might want to look somewhere else. Also, grab the compressor wheel and pull in and out and up and down to check for shaft/bearing play.