Jimbborx7

I only get 7-8 psi on my second turbo. It's consistent, and it's been the same ever since I got the car about 6 weeks ago.

I've had a good look at as many of the intercooler and vacuum hoses as I can without major dismantling. I've also checked the wastegate control and turbo precontrol solenoids are connecting round the right way. Connecting them the other gives around 4psi on second turbo.

I was wondering about temporarily capping the charge relief valve to see if this will give me full boost. If this does give me more boost, will this show the problem lies with the charge control actuator? Before I blow my engine trying it, will the BOV still stop me getting too much boost?

Any advice appreciated!

Engine specs are (as far as I know):
Pan Speed stainless down pipe
HKS filters
ARC intercooler
HKS hard pipes
Big unknown exhaust
Standard(?) cat (With small blow)
Pan Speed modified ECU

DamonB

Yes, you can cap off the CRV to see if that's a source of your boost leak. As for the BOV, that will not limit boost in any way; it merely vents boost at lift throttle conditions. The only thing that controls the upper boost limit is the wastegate.

What does your boost pattern look like? What boost do you get on the primary and at switchover? Your low secondary reading could be a clogged cat as they typically show themselves as low boost on the secondary only.

Clogged cat pics

My cat failed while I was at the track. Car always had a 10-8-10 boost pattern and in the third session of the day I noticed the boost appearing to be low. The primary would boost to 10, but the secondary would only do 9 psi. Then 8 psi a lap or two later. Then 7 psi. Then about 6.5 psi. The brick crumbled and then it just got packed tighter and tighter and therefore clogging the flow. The primary turbo acted fine the whole time. A clogged cat is like a clog in a drain. As long as the flow is not enough to back up behind the clog, everything is fine. Once flow increases the clog backs up. There was not enough of a clog to hinder the primary, but the secondary was having a tough time.

Jimbborx7

So if I cap the CRV, will the wastegate stop me getting too much boost, or will I have to watch it really carefully?

My boost pattern in 13-5-7

It's always the same, with only slight variations depending on the weather. I've done about 400miles since I got the car 6 weeks ago, and there's been absolutely no change.

Is there any other indication of a blocked cat? It's a Jap RX-7, so there's no pre cat.

Car runs perfectly other than the lack of boost on 2nd turbo

Mattco26

If you disconnent the vacuum line to your BOV, it will open at whatever pressure the spring inside is capable of holding, but its probably up at like 17 or 20 PSI.

DamonB

You are pretty confused; the BOV has nothing to do with system boost pressure. If you disconnect the WASTEGATE vac line or remove the pill from the wastegate line then boost will only hold to 7 psi as that is the rate of the spring inside the wastegate actuator.

DamonB

Well, it could be lots of things as always with this car You can safely cap the CRV without overboosting, just realize your boost will be slightly laggy. Your boost pattern tends to support the idea of a blocked cat along with some other possibilities. Try reading up over here and see if it gives you anymore help before we all tell you the 10 different things it could be There might be something there that makes sense to you.


Derek Vanditmars turbo troubleshooting page

rpm_pwr

Some BOV's do tend to freeze up (the BOV's on Mk3 supras are notorious) but FD BOV's go forever.

Regardless, blocking up the CRV is a very good start. I've had
a CRV that wouldnt close before. The CCV is fine, you wouldnt be getting full boost on the primary if it wasnt.

-pete

dhahlen

iTrader: (5)

Same problem here with the 13-5-7, no clue what to do.... was working fine now it just started to happen. 1200 miles on engine.

Jimbborx7

Turns out I had a blocked tailpipe that had collapsed internally. I also had a slight leak from my inlet manifold gasket.