10-8-10... Sometimes
 

Hi,

I am going to investigate what the problem is this weekend with the Mityvac pump I just bought. I would just like to see if anyone has had the same problem and can help me locate the problem quicker. BTW, I have done a search and although there is lots to read, I can't find anyone with the identical prob.

Ok, from 2000RPM with WOT, I get 10-8-10 while going up to redline. In the 1000 to 4500RPM range everthing seems normal.

The problem is when I let off the gas/change gear ovove 4500RPM. When I re apply WOT, I get low (2psi) boost, then if I wait, it will eventually increast to full boost(after say 5/6 seconds).

i.e. Second gear, WOT up to 7000RPM, all ok. Change to 3rd, RPM drops to say 5500, low boost with WOT. After 5 seconds or so, boost eventually comes back to 10psi.



I suspect it's a 1 way valve from the pressure tank, or something to do with the charge control valve but I am definitely no expert.

Any help is much appreciated.


Trevor

Oh, I forgot to mention, I replaced all the vac hoses with silicone ones, and just changed my CRV because it was sticking open.

Trev

Its your one way check valves. I had the same problem last year. There are two green/black valves and two green/white valves, replace them.

I replaced the check valves. Still the same problem though. I think I will have to check the solenoids this weekend. Can anyone else help!!??


Trevor

fd3typer2,

do you hear shoooong sound after 4500rpm when you shfiting gear?

Some silicone hoses are so soft they may be collapsing under high vacuum when you shift. If one does, it could cause this. I.e., slow return to full boost could be a direct result of a hose being almost closed off due to collapsing.

mine has the same symptons and mine does shooo after 4500 rpm and it also shoos sometimes after the bov goes off

Hi,

no I don't get any whooshing. I did have some time ago but it was a torn hose which was not cut at the end properly. I will look into the bent hose thing. I definitely have noticed at least one which looks suspect. I will try to get a photo of it if i can


Thanks very much for your ideas guys.


Trevor.

Thanks DaveW.

I removed the intake manifold and what do you know, the front hose from the turbo control solenoid (I think its vacuum in this hose when the secondary turbo is supposed to be online) was bent and had a kink in it, nealry closing it completely. guess that this is the offending hose. There is also one other suspect hose which I will change.

This is what I would like to ask next. While the manifold is off, what else can I check. So far I have done this:

All 5 1 way check valves with vacuum pump

Check for leaks or popped off silicone hoses

Check for kinks or pinches

Checked solenoids with vacuum pump to see if they leak.

Actually I want to know the proper way to check if a solenoid works. Is it just a matter of getting a vacuum or pressure in one outlet, they applying voltage to see if it is venter( i.e. flow is diverted to the other outlet)

Any other pointers are very welcome, as I have until tuesday. That when I should finish polishing the intake manifold.

While doing all this, I have had made a new thicker radiator. Anyone have any pointers on this. The company is replicating the unit to my one, just making the thing thicker (about 2 1/4"). Anything I shold look for or ask for?


thanks guys.


Trevor

I would think about changing the AST, as they are known to crack and fail.

kinda off topic but what kinda problems were you getting before you replaced the CRV?

CRV problems
 

My problem before changing the crv was mixed with the above mentioned one. Primary boost ok, sometimes i would get secondary, sometimes not.

This was mixed with the "not getting secondary if i lift off or change gear" problem.

Tuesday will have some feedback as I will be finishing off the work and tests today.


Trevor

Update
 

Hi,

today the car will be ready.

Here is a pic of the new radiator. I got it made locally and seems ok. Should definitely cool better than the stocker.
http://cubestudio.net/trevsrx7/sidebyside.jpg

Here is the kink i found in one of the hoses. I hope this is what was causing the problem. I also found one which was not so bad but fixed it anyway.

http://cubestudio.net/trevsrx7/kink.jpg

Here is the polished manifold. I still have to go over the top of it with a final polich. Could be better but I don't have all the necessary polishing bobs handy.

http://cubestudio.net/trevsrx7/polishedmanif.jpg


I also vac tested all the solenoids which seem to be ok. If this doas not fix it I guess I will have to do the heat test on each solenoid and double check the actuators. Thats all left to test!

Trevor

You would want to zip tie down the vac hoses, no ?

what the heck is this? i've had it intermittently for some time. for a while after my rebuild i was only asking my turbo's to limp around before i went PFC but now that i'm shooting for stock boost i'm finding new problems.

lately i've been getting flaky secondary boost among other fun things. it cuts out to about 4psi for me. most of the time it's fine @9-10 psi but sometimes i get this, and i'm somewhat sure that funky sound as well. but that might not sound every time, maybe only if i wind up the 4psi secondary to the next shift point and take the next gear.

im getting the same thing as well.this weird sound when I let off the throttle and then step on it again.Boost barely wants to build and sometimes the needle on the boost gauge goes up and down very quickly for a few seconds.It sounds like I have a disco under the hood of my car because instead of getting that whoosh sound I get this booooooouuup sound.Crazy I know.Needles to say my secondary boost sucks and at transition the boost that the primary turbo builds up takes a big nosedive.

anyone else have any ideas?