Hey guys, lately I have only been boosting to 4psi when it is set to 9psi. Checked i/c piping for leaks-none. I have a greddy 18g (td05?) and it has an internal wastegate. Today i pulled the vacuum line off the wategate to see if that is what was making the boost low. Well i drove it carefully and realized it can go up to 15psi easily. So is the wastegate the problem or is this normal with unplugging the w/g? I thought if it had a boost leak, unplugging the w/g wouldn't have an effect. Also where can i buy one of these wategates? I searched and could not find anywhere but greddy's site. Thanks

 

You can always turn it up with a boost controller.

Did it go to 15psi fast or was it really lazy?

 

It got to 15 real fast

 

boost leak

 

So you don't think its wastegate related?

 

Ok, today I took off all the plumbing, checked everything and put it back together. Still only 4psi. Will putting a boost controller on it be a temp fix if the internal wastegate is bad? If not, where can i find a new 18g wastegate?

 

i cant see a waste gate going bad unless the spring its self is getting weak other than that any other problems with the wastegate would give you more boost. is there a rod on the waste gate arm that could have got loose and changed the distance of the rod??

 

i think i know what ur problem is, u need to adjust the waistgate actuator arm and make it smaller, screw in the end part that connects to the swing arm on the turbo exhaust housing, this will tighten up the arm and make sure that the flap will stay closed til it reaches the right boost level, it could be too loose now and basically ur flap has no closing pressure on it so its just lettin air go bye not making the turbo boost right.......so u wanna tighten it where its really pullin the flap to its closed position but make sure its not too tight or the flap wont open enough and u'll get boost spike...i tighten it and then pull the waistgate arm open and make sure it opens up about a quarter inch, this is enough to let the air bypass so it doesnt boost spike, just try tightin it a few turns at a time and see if it helps. goodluck

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbinteg &raquo;</TD></TR><TR><TD CLASS="quote">is there a rod on the waste gate arm that could have got loose and changed the distance of the rod??</TD></TR></TABLE>

 

I will try to adjust it all the way tomorrow and see if that helps.

 

I can think of a lot of small things that can change 9psi of pressure at the actuator to 4psi at the gauge. The gauge will usually show the difference between local atmospheric pressure, not absolute pressure. If you hooked up a volt meter to the map sensor, you'll probably find its different from your gauge. Gauges can be more than 1psi off. The other thing it could be is pressure drop from the FMIC and piping. If your wastegate is hooked up to the nipple on the turbo, you will see 2-5psi less between the turbo outlet and the throttle body. I always suggest hooking everything to the same area, as in a vacuum manifold. <U>The wastegate, map sensor, and gauge should come from the same spot - see the exact same vacuum/boost signal.</U>

If the wastegate is genuinely 9psi, then the only thing a slightly loose flaper will do is spool the turbo up late (a few hundred rpm). A wide-open flapper will not allow any boost to build until very high rpm's (a few thousand late). If you disconnected the wastegate actuator *and* the flapper was wide open, it still shouldn't have made any more pressure.

I'd suggest just buying an ebay manual boost controller. I had a very old one that worked perfect, although it was initially set very high (had to cut the spring). Assuming you put it in properly (and adjust it slowly), you will get to 9psi no problem *even if* your gauge is off and you see a pressure drop between the wastegate line and the throttle body.

 

I also noticed that my vacuum at idle is lower than it used to be. it is now (26-28). Could this have anything to do with this and what causes high vacuum?

 

i would swap the boost gauge with another one i cant see it being that low maybe the gauge is off

 

^^
Yo frank, your right, I swapped the boost gauge out of my fiero and it now reads correctly. Maybe it was all in my head that the power was not there because of seeing 2psi on the gauge. Anyway things are looking good now. Thanks

 

hmm. i never thought about a bad boost gauge *smacks self in head*

 

nice man good to hear now you just gotta drive that thing up here so i can see it

 

Yeah Whenever you wanna meet up. Im not sure if tri state tuners is still on thursdays but that would be cool or the meets near you.

Anyway I did smack myself in the head whe i saw the gauge was bad : /