Ok i just purchased an 05 evo about a few months ago and I put in a boost gauge last weekend. It's a SW gauage that I bought from AMS (thank god they are 15 minutes down the road). I put it myself and used the plastic tubing that came with it. Now i've worked on turbo cars for many years (my last car was 95 tsi) but i've never seen boost spike like this. It doesn't matter if i'm in 1st, 2nd, or 3rd gear but when i'm at WOT. My boost spikes to 21-22 psi then falls to 16-17psi, goes back up to 20psi and falls and stays at a constant 19-20psi till redline. I haven't touched anything on the car besides installing this damn gauge. First off that initial spike is a bit high but why would it drop down, go back up and then stick. Very weird.

 

hmm usually it goes around to 21-22 psi then drops to 16, thats why ppl get an MBC to keep the strong psi till redline. Ur case its mad weird ? dont kno :0

 

it could be the gauge..

 

Check your vacum line that goes to your boost gauge. Did you use small zip ties or clamps to make sure all connections are air tight.

 

This what I did so far as the connections are concerned. I used the stock plastic tubing that came with the gauge and I used teflon tape on all connections. Now on the opposite end from the gauge I went to ace hardware and got an extra vacuum connection to convert the plastic tubing to the regular rubber vacuum hose so I can just run it through the firewall T it into the intake manifold hose. I tested everything to make sure it doesn't leak but I did use small zip ties. Where can I get clamps small enough?

 

thats pretty normal. My car does the same thing and I have the SW gauges as well. Its just the computer trying to hold the boost and not doing a very good job.

The initial spike is normal. The boost taper is normal. Even on a dyno my cars boost graph looks all silly like that. I wouldnt worry about it. Lots of guys do use the MBC but when you do, remember if the computer senses knock it can no longer lower the boost to compensate.

 

Did you buy the car new?

 

why not just run silicone the entire way? I never like the platic stuff, kinks too easy and stands out to much, and the connections are more likely to leak imho but anyways.... also did you tap before or after that solenoid on the mani? just curious....
Also have you tested for any boost leaks anywhere on the ic piping?

 

it is pretty normal...before i had a mbc, it would spike to 21-23 then gradually fall to about 16 and maybe sppike back up to 18 1st - 3rd.

 

Don't look for an answer to your problem as there is none. What you are experiencing is entirely normal. You're quite lucky that it creeps back up to 19 as mine would hover around 17. Want smooth boost? get a MBC.

 

Use the regular vacumn hose all the way. I don't like that plastic stuff that comes with the gauge, plus it doesn't seem to hold up to under hood temps as well as the other stuff.

 

way off topic... but what does wot mean???

 

WOT = Wide Open Throttle

 

wide open throttle

 

you answered your own question.

WOT = way off topic HAHAHAHAHAHAHA