Since I had the turbo pedestal changed, I seem to hear the turbo hiss. I know it is the EBPV activating. However, today it is 59 degrees ambient. Why should it be activating? It thought it comes on only when it is cold? I can drive for half an hour and it still hisses. Wife drove it home 70 miles away and it hisses.

The hissing is only when you hit the throttle and not in idle. basically boost has to be over 5 psi for me to hear it. Any ideas of what to look for? TIA

 

That shouldn't be happening at those temps. Oil temp and air temp are the keys the PCM uses. When air temp is below 45 the PCM can command the EBPV up to an oil temp of 168*F. or a short in the wiring could cause it.

 

It seemed to be ok till we replaced the turbo pedestal. Is that where the Oil temp sensor is? I took out the air temp sensor in the air box and it tripped a code but the EBPV still activated.

 

I called BTS since the shop I had to the turbo pedestal wanted to do a break torque test to see where it was leaking from under boost. Brian said it was ok and I wouldn't hurt a thing. Anyway, he told me that since the turbo pedestal was done, he was sure it was a hose on the CAC that was leaking. Well, I took the pipes going to the turbo off and the CAC pipe off. Nothing looked out of the ordinary. Everything was the way it should have been. OK. Since I was there, no harm in taking it apart and cleaning it. Put it back and took it for a test drive. Everything seemed to be OK and nothing changed EXCEPT for the fact that the hiss that I thought was the EBPV was gone. I was getting 22 psi boost again. Is that man great or what?

 

It doesn't take much of a leak to cause a hiss and nothings harder to find than that last small leak.

BTW the EOT is on the back of the HPOP reservoir pointing toward the turbo.

 

Thanx. So what is that thing on the turbo pedestal with a plug on it?

 

Exhaust back pressure valve solenoid.

 

Thanx Alan