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Thread: Umm, mysterious boost increase

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Posts: 1-10 of 14
2010-05-28 09:43:52
Umm, mysterious boost increase
On my way to work this morning, like any other day, I gotta boost! On the highway I stuffed my foot to the floor for a nice 5th gear pull. As she ripped, I said to myself, "that feels great!" only to my se-rprise I was making 18psi!!!! No good! She's set and only ever made 14psi! She's not built for 18psi! Only adjustments I've recently made are installing wideband and leaning it out in realtime. WTF would cause this!?!
2010-05-28 10:24:49
was it really cold out ?
2010-05-28 11:25:40
Internal or external? Wastegate spring or arm could be sticking, gauge could be bad, boost source could be kinked, controller could be bad, etc etc etc
2010-05-28 19:36:35
try it again, if it persists do a simple test, conect the wastegate directly to the vacuum line, (eliminating the boost controller), if problem persists then its a wastegate problem, if it runs the low boost without spiking. its probably a boost controller issue, then reconect boost controller and try again... wont take you 30 mins to do that
2010-05-28 21:15:51
Originally Posted by boostednx
was it really cold out ?

x2 I never realized how much of a difference temp makes on boost when you have a boost controller until I finally turned up the boost in my car.
2010-05-29 00:59:23
i was going with the cold theory, but it was roughly 60* this morning on the way to work. i dont drive in winter, but fall and spring mornings get cold at 40* NEVER made over 14psi before today. still, outta work today with temps hitting over 80*, still spiking 20 then holding steady at 18psi......just popped my hood to turn down the MBC and see whats what, CLIFF nailed it, MBC. the freakin source line came off. BUUUUUT, now i need MORE BOOST! the bug sank his fangs way deeeeeper today! MUAH HAHAHA!!! now im stuck on EVERYONE saying a t25 is useless over 14psi. i felt a significant increase in power today!!! can my motor with stock internals hand more? totally re-built avenir block, stock internals, VVL headgasket, arp headstuds. cams, port and polish, bla bla. thanks guys for your help!!! :-)
2010-05-29 01:11:42
i wouldnt push it with that t25. just making more heat but screw it if you want to do it than do it haha.
2010-05-29 01:12:29
You sir, have boost creep.

More boost may make a bit more torque in the lower revs, but will tax the turbo more. Be careful with the T25 on high boost levels. They like to melt things.
2010-05-29 01:24:11
Time for a disco potato or GTiR T28.
2010-05-29 02:06:11
Morgan; it was a malfunction. I didn't do this on purpose.
Coheed; thanx for tip. That torque would explain gettin loose in 4th and 3rd gear torque steer like it was 2nd!!! She's def going back together and only making 14psi like usual.
Benito; agreed! Original build plan was for gt2871rs! Time for more boost!

And I thought I was content with what I had till today's "failure!" lol >:-)
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