boost drop off at high rpm's?
Dec 21, 2008, 07:18 PM
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boost drop off at high rpm's?
Ok so I have a 05 evo with basic mods such as hks 272's, just a hks catback, walbro 255, 750cc injectors, intake etc etc. the problem is at wot it will build boost for a split second and then just drop... theres no boost leaks so im wondering if maybe it could be a problem with the wastegate?
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Dec 22, 2008, 05:42 AM
#8
It's typical for the pressure to drop after the spike, and really not much you can do about it on a stock turbo except tune around it. There are ways to lower the spike a tad and raise the pressure after the spike to some degree to match (using EcuFlash), but a lot of it has to do with the wastegate itself and the housing not being able to hold that much pressure at higher rpm's.
Dec 22, 2008, 06:28 AM
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No I know its not gonna hold the boost up top, its set for the stock boost but it wont even make it to 19psi at wot it will hit 15psi at about 4k then just drop off totally... And I have no logger or else I would take some logs to post up. Normally it will hit around 18psi and drop off to 16 and occasionally spike at 20 and drop to around 16. I'm pretty sure it has something to do with my wastegate, I'm gonna pull the turbo today and check everything but what should I specifically look for? Before I pull the turbo I'm gonna check for boost leaks one more time.
?
Dec 22, 2008, 07:39 PM
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I worked on it a lil today and when driving around at WOT it started sputtering at 6k, the boost held a little better some times but still kinda having the same problems...
