Boost Keeps on Rising!

[Guest Anonymous]

Hey guys, as some of you know I finally got my Mazda intercooler installed. I installed it and borrowed my friends Greddy TVVC boost controller. Basically its just a knob which you turn to raise or lower the boost. My problem is that it wont keep a constant boost. If I set it to say 10 psi in first gear, the boost will only go to around 6 or 7 in first, but 14-15psi in third gear. If I set it to 12 psi in third, it will only go up to around 8 in second and 5 or so in first. Its really annoying, 13 psi in first gear is something ive never experience and was one crazy ride, but then i have to go screw in my boost knob and turn it down for second gear and do the same for third. What do you think it could be?

 

I was thinking it was my i/c piping at first, but it holds up fine to 15 psi in any gear, i just have to play around with the boost. I was also thinking it was the boost controller, but my friend who used it before me was running 16 psi with no problem. What could it be? i dont want to spend $300 or 400 on an electronic boost controller, i know its probably something simple.. thanks

 

Scott

 

ps: Scottie, I know you can help me out on this one! heh, i hope someone can. Thanks Oh, btw, i am running a t3/04e turbo

[stony]

Hi

 

Here's my 2 cents

 

if you had a leak in your piping you'd have problems building boost....check your hookups and hoses make sure you don't have any cracks or splits in the hose.... make sure you have the controller hooked up correctly and not backwards... if its hooked up backwards will cause all kinds of problems. do you have an external wastegate? or is it a stock turbo you upgrade to to4e? your wastegate could be too small... just a few of the things you can look at

 

stony

[Drax240z]

Moved this to the turbo forum from the 6 cyl forum.

 

Sorry I can't offer much advice on the problem, though I am following it, so place post when you find the answer!

 

------------------

Richard Lewis - 1972 240z, Powered by a Nissan 2.8L Turbo Inline 6.

Drax240's Turbo Site

Beginners Turbo FAQ & Answers

[Guest Anonymous]

Well, I sort of figured out part of the problem. I had my lines going to my boost controller waaay to long. They were about 5' each. I cut them down to about a foot and just put the controller in my engine bay. Now it is keeping a fairly constant boost throughout the gear. The problem I am having now is that it will "spike". It will go to around 15 psi then drop to around 11 or 12. it does it really bad in first and second gears though. It also sometimes dies out on me in first gear at high boost. It will spool up and get around 15, then leak down and around 5k it pops a few times. I havnt really tried keeping it floored because i thought it was detonation, so i did a full run in first gear and shut it down, checked the plugs and they turned out fine(actually really tan, i thought i would be running out of fuel but i wasnt). It doesnt do it in second gear or third, but i havnt tested third out at high rpms. Just some info, maybe someone has had this problem before. Thanks

 

Scott www.flex.net/~mgwilson

[Brad-ManQ45]

Is this somewher around 4500-5000 rpm accelerating HARD in first gear?

 

Does the engine feel like it loses power?

 

You back off and "feather" the throttle in (roll it on instead of pounding it to the floor) and it doesn't happen (and doing this actually gets you there quicker because the engine doesn't "stall")?

 

I'm not sure, but I think we're experiencing surge. Our big compressors are being driven too quickly by the turbine for the amount of air the engine needs/can handle so the compressor "stalls".

 

I would love to hear what the gurus have to say about this.....

 

Brad