Hi all, I have been searching all over the forum and can't find out why I am having this problem. I have a TBE with o2, and for some reason now my vacuum on my boost gauge reads high when it is off throttle. it reads -25 or so, only in gear. when I shift to netural it goes back to -19 or so. I had the TBE for a few weeks now and it just started doing this. It seems like the turbo spools slower now. but it still boost to a 20psi peak. Can anybody tell me why its doing that?? Any info would be greatly appreciated. Thanks!

 

Could there be a potential for your boost gage line being pinched in your gear selector levers on the tranny? ie., is your boost gage line running anywhere near there?

 

That's normal.. vacuum wouldn't be what i'm worried about, it would be the boost. Never mind what the vacuum is in gear, at idle if you have stock cams etc it should be from -20 to -17 hg vacuum.

Do a boost leak test to figure out if there are leaks in your system... with a TBE and O2 housing your turbo should be spooling quicker, maybe there is a leak in the intercooler pipes by the intake side when you took it apart to put on the O2 housing.

 

It used to spool alot quicker after I got the TBE, but it was boost spiking to almost 25psi and the fuel cut would kick in. I hope its not knocking . I don't know if that did anything to it, I reset the ECU and it still does that. Hmm....I don't know. But I'm getting licp, GSC S1 cams, fuel pump, mbc, and a tune next week. so I'll see if that helps or not. Thanks for all the help guys.

 

Vac seems about right. What exactly are you worried about? If you hurt something from hitting fuel cut?

 

yeah, mine reads around -18 to -19 normally at idle.

 

Your numbers look fine. You usually pull more vacuum on decel. than at idle.

 

What I'm worried about is that when I lift off the throttle it would dip to -25 and stays there, if I'm still in gear that is. It idle's fine when I'm not in gear tho. and for some reason it makes the turbo spool slower. .

 

That is completely normal and should have no effect on the turbo spooling.

When you let off the throttle with the car in gear, using the engine to slow the car. The butterfly in the throttle body closes, very little air is going into the engine and, since it is turning a higher RPM than it does at idle (trying to move more than it does at idle) your vacuum goes up.

The spool portion of the problem is probably in your head. Is there something that I'm missing?

 

Yea maybe it is in my head, but I swear it wasn't like that before. I remember even when I was in gear and lift the throttle it would be at the same as when im in idle. I think I'm just imagining things.

 

oh boy!

 

That number is very normal at idle. Although it isn't -20 vac, -20 is more like -10 vac.

 

with my hks 272
my idle is at -13to -15 and on decel its -20 to -25

 

I had cams installed since and I idle just like you now.

 

if you rev the car to 3000rpm and hold it at 3000rpm should the vacum creep back down to -20. Is this telling me I have a leak?