Jedon

I finally got my new engine broken in and then a week later my second turbo goes away :-(
Everything is great up until 4000rpm (not 4500, it is 4000 indicated), then it makes a big sighing sound and goes to 0psi.
I swapped the connectors and hoses on the wastegate and precontrol solenoids and it made no difference.
I pulled the hose off the CRV and it made a noise so I guess there is vaccum.
I pulled the UIM off and looked for broken hoses, found one but I think I sheared it when taking the UIM off. After putting it back together there was no difference.
I pulled the CRV hose off the air box to see if it made extra noise but it didn't, then I pulled the ABV hose out of the air box and it makes nice pwsht sounds if I let off before 4K rpm, otherwise the noise is still the same.
I did the hose job before the rebuild (the extra 1psi I gained blew the engine :-) )
The engine is streetported and has a M2 9.5lb flywheel and ACT clutch, otherwise the car has a stock drivetrain.
0-4000K RPM = 12psi
4000-redline = 0psi
What should I do now? Swap out the Turbo Control solenoid?
Thanx!!

Lost Time

I just had the same problem. It was a hose that had blown off under the UIM behind the pressure tank. Check all the vaccum hoses associated with the CRV.

Jedon

So do secondary turbo problems mostly have to do with the CRV?

P'cola FD

Not all secondary problems, but if primary is working fine, and secondary has no/almost no boost, then it is a very likely candidate. Usually the CCV can be involved as well, since they share a pressure source. There's a pretty good description of how to check for problems here https://www.rx7club.com/forum/showth...threadid=98645

Alex

I agree that it's in the CRV or CCV system. It sounds like the CCV is opening but the CRV is not closing. If it was the turbo control you should still see boost from the first turbo, just maybe not full boost.

allrotor93

iTrader: (126)

i just fixed the same problem. i was getting full boost on first but only like 5-6 on the second. i found a check valve that had busted open underneath the pressure chamber. now i get 12.

Jedon

I get 0psi on the second though, not 5-6.

Lost Time

Same problem I had. Check under the UIM for a hose that blew off.

jamespond24

iTrader: (13)

I have the same problem too. So which hose could cause this?

artguy

toadman had the same problem too..however his was an exhaust leak...bolts on the turbos and bolts on the DP.

j

jet7

I had the same problem. I fixed it with changing all the vaccum lines, they can't stand the heat. Make sure that you use the silicone one's. Changing them twice sucks the big dick. I changed them three times be for I used the silicone lines. good luck

jamespond24

iTrader: (13)

Where can I get silicone hose?

johnchabin

iTrader: (2)

http://www.hosetechniques.com/

SpeedracerRX7

It very well may be the Turbo control solenoid. It took me forever to find and diagnose because I was playing with couplings, CRV valves and vacuum hoses. My problem that was very similar. It was a pain to get to because I had to take off the UIM and coil just to get to it. Here is link to the thread where I posted mine just so that you can compare.

https://www.rx7club.com/forum/showth...hreadid=114721