Can't boost more than 3psi...

[joghia]

Hey guys. Here's the situation:

Alright, interesting deal here. My MSP, ever since I owned it, has always idled at -21 vacuum (approximately). Deceleration (while in gear) was -23/-24 approximately. It would also properly boost to 6.5psi when I would step on it. All was good.

Then, 2 days ago, I was driving and noticed that the idle vacuum was -19. I thought that was pretty interesting. Deceleration would then be -21 approximately. The problem is that when I step on it, boost now hits 3-4psi tops and won't go any higher!

I do have an intake with aftermarket charge piping and have always had a feeling that I had some sort of little leak somewhere in there. Maybe that's my problem? If so, how do I check my couplers for leaks?

Then, I got more driving impressions from this weekend. The car still can't boost more than 3psi, so I am now refraining from accelerating with anything over 0psi. Rather be safe than sorry before I really know what the problem is. As for my vacuum, it's very weird. My idle vacuum will be -21 (like old times) sometimes and my deceleration vacuum will be -24 (like old times) and the vacuum side of the equation will be perfect. Then, 10 seconds later, deceleration vacuum will be -20 and my idle vacuum will be -19. It will literally fluctuate from time to time. I don't actually SEE the fluctuation when I'm at idle for example, but it'll be good at one red light and then up higher at the next red light. Would a fubar'd wastegate be doing this fluctuating vacuum?

I'm thinking this could either be:

- A vacuum leak (I DO have a very loud whistling intake...)
- A crapped out boost gauge
- A stuck open wastegate

Any comments, suggestions? I have to test the wastegate but the vacuum line seems to be seized on the T and I can't get it off :S. Will try some more when I get the time.

 

[HondaEat-R]

I'd bet it's a intercooler pipe leak. What's your MAF location ? Stock or relocated? Does your boost spike to 6-7, then settle to 3-4 ? Just check for IC leaks by removing and re-seating all the couplers. Make sure the couplers aren't being clamped right at the edge of the IC pipe, and make sure to use T-bolts.

You can alos get a one ended silicone coupler with a nipple on the closed end. You put this on the turbo compressor inlet and pressurize the IC pipes with a small pump. If you have a leak, you'll find it.

The inconsistent Vac is odd though, makes me think maybe a wastegate issue. Start out basic though, check Pipes.

 

[joghia]

MAF location is stock, right after the air filter. Boost does not spike; it just hits 3psi and won't go any higher (barely makes it to 3psi on the gauge). I will check the couplers as soon as I can. The loud whistling intake is also causing me to think that it's a leak somewhere.

I didn't really get that explanation on how to test for the leak; got a pic of this one ended coupler?

Also, for added info, I've got a crack on the stock callaway exhaust manifold, but no CEL. Could that be a cause too?

 

[harrisonchang]

i have the same problem. Can't seem to boost past 5. Or i'll spike at 6 then settle at 5. I had this when the only mod on my car was my perrin sri. I installed a turbolife fmic, and i still have the problem. Haven't watched my vac yet, but i'll watch that and let you know.

Makes me think it's my wastegate.

 

[HondaEat-R]

Well, what is your boost controller set at, if you have one ? Isn't the stock wastegate set at 5-6 psi ?

 

[harrisonchang]

I haven't installed my greddy ebc yet.