No Boost

[DammitBobby]

I made the boost leak tester and found some leaks. Fixed the leaks but no boost. The boost gauge at idle reads 20 vacuum and it is steady. Engine idles good and seems to run good. I took off the wastegate and checked it seems to be working. I left the wastegate open to atmospere and it I couldn`t hear any exhaust. One thing I did notice that when it tries to boost it makes a screaching type noise. I am wondering if the new turbo is bad. It has no shaft play and it seems to spin freely. I am running out of ideas to try. Anybody have any ideas, advice or questions?

Thanks

[nissanfanatic]

Screaming typically means the turbo is out of balance...

Check for impeller to housing contact in both the intake and exhaust side.

[DammitBobby]

Would that also cause it not to build boost?

[fiznat]

A leak before the turbo could cause no boost, also backpressure in the exhaust? Another silly possability could be a block somewhere in your intake piping (before the turbo). Make sure your filter is clean and there is nothing restricting the air there.

Also *cough* check for rags in your IC piping... "someone I know" did that before and got no boost....

[klattr1]

what kind of turbo do u have?

[DammitBobby]

I had a ZY and had it replaced with one that somebody built for me. They used Garret turbine housing but everything else is custom. So I am calling today to see what they have to say.T3/T40E .48 AR turbine stage 3 wheel and .60 AR Compressor 50 trim.

I am leaning towards the turbo myself. I don`t have any leaks and reading 20 vacuum at idle. the wastegate is open atmosphere and benched tested. When I did the boost leak test I was reading steady 10psi on my boost gauge.

[DammitBobby]

Well they want me to bring the turbo in to look at it and see what is wrong with it. I hope it is the turbo if so I will be boosting soon.

[DammitBobby]

Replaced the Turbo yesterday and let the car sit and idle for 15 minutes. This time I poured some oil in the turbine and removed the fuel pump fuse. I cranked it for a minute to allow oil to flow through the oil line. Drove the car around taking it easy for around 10 minutes. Today I drove it until the car warmed up and boosted a few psi and let off. I did this for around 15 minutes and then decided to boost slowly all the way to 11psi. After that I did a few more slow boosting until finally the BOV blew off! Car pulls hard and even when I was attempting to slowly boost the tires broke loose in 2nd gear. Crappy tires!

FINALLY BOOSTING

[nissanfanatic]

Cool deal.

So did they give you an analysis on the old turbo?

[DammitBobby]

Yeah actually he had me take it apart in his shop. It end up having a very little spot burnt on the center shaft. That caused the compresssor wheel under boost to rub the housing. He replaced the center section and the compressor wheel. Polished the compressor housing where it was rubbed by the original wheel and cleaned, painted the turbine housing.

He thinks it could be one of 2 things.I didn`t give the new turbo long enough time to warm up before boosting the first time.When I first started the car with the turbo on I didn't take the fuse out of the fuel pump and let it turn over for few minutes. The reason I didn`t do that is because I thought there was still oil in the lines because of previous testing.