Boost issue on stock twins !!!

[arrouk]

correction, i think its vac as after reaplying vac from engine (letting revs drop) the tubs return to normal.

matt

ps i have both chambers if you need them.

[shaunwil]

Cool, may be giving you a shout for them once I\'ve tested them with th new gizmo

Just as I need the car while i swap engine in the 1st gen !

Shaun

[m4drx]

Cool, may be giving you a shout for them once I\'ve tested them with th new gizmo

Just as I need the car while i swap engine in the 1st gen !

Shaun

i have chambers, hoses, valves, solenoids and just about everything you need mate so let me know if you are in need.

[shaunwil]

Cheers guys

Want it running right by rotorstock, so not much time :eek

Shaun

[shaunwil]

hi shaun
what was the name off the place you got the mityvac from and how much was it thanks

oops, only just spotted this question. Bought it off ebay for £41 all in, called    
chrometrader0 on ebay !

Just a quick update, I used a foot pump and a bucket of water to test all my one way valves and the easy to get to vac chamber. Found 2 of the valves where leaking. Got some 2nd hand ones off pip while picking some other bits up. Tested them and one was leaking (only paid a couple of quid for them) so had a dig and found a good one off the bits I don\'t need on the 13b EGI engine for the 1st gen !

Just taken car out for a run and the pickup is quicker, slight hesitation (0.35) then full boost, change up again and its 0.35 boost for a few seconds before it builds up again.

I\'ll try and check the other vac chamber in the week but its buried under the alternator !

Shaun

[gmogle]

I still reckon it is one of the solenoids mate and not one of the check valves.

Check this link out:
http://rx7.voodoobox.net/howto/solenoid_check/solenoid_check.html

Tells you how to test the solenoids properly. I reckon when you test yours you will be suprised and I would expect one of these to be wrong.

Check also the vac piping, see if any are kinked or almost kinked as these can collapse when they are warm.

[shaunwil]

I hope its something as simple as that !

I\'ll wire up some thing to do the test and see if its one of them ! Reading through this it definitely needs a pressure regulator in the loop before the control solenoids to stop them from sticking !

Cheers

Shaun

[shaunwil]

Reading that page makes me definitely think its that what is causing the problem.

I just hope it is !

Cheers

Shaun

[gmogle]

Mine had the same problem as yours, it would accelerate through 1st turbo, 2nd would then sometimes work and then other times not. The main issue also would be if I accelerated hard into the 2nd turbo, then let off and put my foot back on. The car would make a loud noise as if it was struggling to accelerate. If I let the revs drop to about 4000 rpm and then accelerated it would be fine.

But when I did my rats nest after that I found 1 way check valves going both ways, loads of loose hosing with one major kink in one and 2 solenoids faulty. I honestly cant remember which solenoid it was to be honest but that seemed the most likely candidate giving me the problem. Did the test as shown above and it would hold the boost before releasing rather than letting off straight away. When I put it all back together and tested it the car felt like new !!

You could plumb in a gauge to show vac pressure going into the chamber to test it isnt overboosting.

Good luck mate !!!

[shaunwil]

sounds like i\'ll need it :Giggle

I\'m going to plumb a pressure regulator in too so i don\'t kill the replacement ones too with 1 bar of pressure

Shaun

[shaunwil]

Pressure regulator thread on rx7club :

http://www.rx7club.com/showthread.php?t=480079

Shaun

[Rixio]

I had thıs problem last year aswell...but it was only random...would happen only from standıng start rather than rollıng...weırd...3 or 4 need replacıng now though so wıll check them next week...ıs there a specıfıc solenoıd that causes ıt?

[m4drx]

ive still got a top notch rats nest if anyone needs any bits,

hth,
t

[shaunwil]

I\'ve taken the plenum off and had a go at checking all the check valves. The upper one and the middle 3 (no egr valve and couldn\'t reach back one) Plus I struggled to get to the front two. I got a coulple of replacement valves when i left my exhaust at pips so ended up unplugging the boost control one and plugging in a known good valve and putting it in the egr position. Boost seems to be good. It running lower that it was before, more like 0.85 bar so will need to change my boost controller settings to compensate.

I put it all back together, don\'t think i have any vac leaks. Nice stable Idle once warmed up and the boost is coming in quite quickly too.

Have to say its a bugger of a job, I was trying to do it in situ without removing alot of stuff and some are just completely impossible to get to !

Should be able to do a few gears on full boost in the morning with quieter roads so hopefully that will show the outcome !

Shaun