Pressure tank

Hi all, I'm still having some bother with the car not pulling correctly. As from my previous thread I thought it was down to the IC but now I'm pretty sure as suggested in that thread its VSV problems.

Thing is I think the pressure tank is not holding pressure for any length of time, Hard pull in 1st and tubby 2 doesn't come online, change into 2nd then everythings fine and same through all the gears. Same thing happens when trundling in 6th and jumping to 3rd, tubby 2 doesn't want to know.

Has anyone had any experiences with the pressure tank and what to check? it's in a tight spot and I can't find the pipes going into it to check the hoses.

Anyhelp would be much apreciated.

Mike

Ask Graham S, I 'think' he has got the same prob.. and has tried 2 pressure tanks... but might be something else to try as well....

Thing is I think the pressure tank is not holding pressure for any length of time, Hard pull in 1st and tubby 2 doesn't come online, change into 2nd then everythings fine and same through all the gears. Same thing happens when trundling in 6th and jumping to 3rd, tubby 2 doesn't want to know.

Do you hear pressure being released when removing the hoses to the IACV and EGCV VSV's? Have you tried running in parallel? Fitting a boost gauge really will help in getting to the bottom of this.

Thanks mate, Yeah pressure released from the IACV but not the EGCV (done at different times of course).

Thanks mate, Yeah pressure released from the IACV but not the EGCV (done at different times of course).

When I had similar probs pressure only ever released from the IACV pipes, when revving the car from inside the engine bay can you see both valves actually working??? the IACV vsv should activate the rod straight away while as the EGCV rod needs over 4k to get moving, if the IACV doesnt work or is not consistant it's probably your problem, this was mine anyhow, and once fixed and a dyno session later I had an extra 50bhp,(fast show voice/which was nice )

Can you find someone local to you to test this? the valve literally takes 30secs to take off.

Plus you'll be wanting to test this first as the pressure tank is a bitch to replace.

Oh as Stevie says try the 5min TTC mod, if you have extra hosing that'll help but not compulsory, check the thread here:

http://mkiv.supras.org.nz/articles/andy.htm

in this way it bypasses the vsv's, if boost can be made you know that it'll either be the IACV VSV or EGCV VSV, boost gauge is the best way to see what's going on, but maybe you'll like ttc and if it works can keep it that way if it's all good.

I'm not sure on you mods but TTC does give a boost spike which aint nice, if you have both cats in though you'll be fine, it's gets louder too

Thanks for your reply,

The car is totally stock apart from a cat back exhaust. I'm going to do the blow test on the pressure tank feed and hopefully feel the resistance of a healthy tank and vsv connections.

I've got the air compressor in the garage so I can test the actuators 10psi is all they need I think.

Just printed off some info for connecting up TTC so I quite like the sound of it. Might even try it tomorrow.

Am I right in saying that if the pressure tank or pressure feed hoses are leaking then TTC wont work correctly?

I've been trawling through the search button and this seems to be fairly common but rarely fixed.

PS: Havent checked to see the IACV working yet, just getting my head round where everything is at the mo. Cheers. What I thought were split pipes on the EGCV VSV was actually the wastegate VSV. oops:)

thats right, if ttc isnt working and it's definately been set up right then you could looking at the pressure tank, lucky for me it wasnt my problem so I stopped my reasearch there, but hopefully it wont be yours! if it does turn out that it's just a vsv, leave it in ttc until you source another one(i'd recommend putting a post on here) it's actually safer to run in ttc than seq as when the vsv's are playing up they mess with the turbo's!

It's an age thing too.

Well I think I know whats going on now,

Checked hoses to the IACV and EGCV and all fine you can't blow down the hose from the vsv to the actuator and blowing down the IACV vsv pressure feed I feel the pressure tank resistance.

Problem is when I try the VSV to EGBV actuator I can blow, not alot but I can do which I think must be a leak.

I done the TTC mod this morning and everything went fine, first boost the exhaust got louder and I checked to see that the IACV and EGCV were opened.

SO I'm guessing this leak is just enough to drain whats left in the tank on first demand so the valve is trying but not quite getting there, but I can't confirm this as it's in a hell of a place.

I will try later on though, too nice a Sat for this.

Problem is when I try the VSV to EGBV actuator I can blow, not alot but I can do which I think must be a leak.

 

SO I'm guessing this leak is just enough to drain whats left in the tank on first demand so the valve is trying but not quite getting there,

The EGBV VSV isn't fed by the pressure tank.

I've got a spare pressure tank you're welcome to if you find you need one.

Thanks Jake, I think it's fine as it's holding TTC mode ok but don't believe me just yet.

The EGBV VSV isn't fed by the pressure tank

Ahh ok, the EGBV actuator is connected into the same line as the pressure tank feed venting through the EGBV vsv to the pressure dump outlet. When the vsv shuts the pressure has nowhere to go so opens the EGBV. So sh$t i'm blowing down that line to the actuator and it's going back into the pressure tank feed point. I need to try that with my thumb over the feed

Pretty sure the pressure tank is fine, It's held pressure for a few hours no probs and when I pulled the feed to the EGCV it vented and quickly closed as did the IACV.

Better check the vsv's then. The car is boosting fine in TTC.

Better check the vsv's then. The car is boosting fine in TTC.

If you don't already know there's links on how to do this on the bottom of this page.

Thanks Stevie that's really helpful. Job for tomorrow I think.

Cheers

Mike

Woo hoo, just checked all the vsv's and found that the resistance on the EGBV vsv is all over the place, 47 ohm was the best only achieved by pushing the pins in one direction. Pushing them other ways achieved mega ohms and open circuit. 38.5 - 44.5 ohms at 20oC is what it should be.

All others were giving stable readings. Also found that the wastegate VSV is passing slightly so that can't be too good.

I'll get them two replaced and see how things are after that but I'm enjoying TTC for now and i'm quite happy with the loudness of the exhaust now. Too quiet before.

Thought I'd add to this just for completeness, I fixed the car today after fitting another EGBV vsv from Jezzybabes (cheers mate:thumbs: ).

Before fitting this I tested all the actuators by connecting 10PSI into the pressure tank supply from the manifold while in TTC mode. This firstly made the IACV + EGCV valves open quickly proving all the hose connections then using my thumb to block off the pressure from the hose going to the EGBV vsv I could check that the EGBV was operating while listening for leaks.

At first this was very tight and gave a crack when it first moved but it started easing off. You have to get your fingers under the turbo heat shield and feel the actuator rod moving.

So today I fitted the VSV and returned the car to normal but damn it the 2nd tubby wouldn't spool atall with growling noises and lack of revs after 4k:( So got back home and low and behold I found the EGCV vsv plug dangling. Out I went again and this time it felt great.

Forgot how smooth the seg mode is as it felt slow till I looked at the speedo and the dump valve goes all the time now with the 1st tubby:d I had fitted an SSQV last month while in TTC.

Looks like a sticky EGBV and high resistance EGBV VSV were to blame for the 2nd tubby coming in late. Thanks for all the help guys and to Ian C for the guide in the tech section, that plumbing diagram has been a godsend.

Did it take you two months to source a VSV!

Well it kind of did but I wasn't really trying hard and I was having fun with TTC for a good bit till I got fed up with the exhaust note. I wanted to be absolutely sure the what the problem was so I checked everything over and replaced a few hoses.