Thursday the 12th of this month my exhaust was installed and flashed ecu were put in my car, the car was a rocket and everything was great. The next saturday my boost gauge was installed and my mbc was next so I could turn it up a few pounds. Then wednesday all of a sudden my car is boosting to 20 pounds then tapering back to 15-16 psi when the day before it was boosting to 21 and tapering back to 20. Everything worked perfectly for 6 days then all of a sudden this happens. I have checked every vacuum line the intercooler pipes and plucked every healthy strand of hair form my head trying to fix this problem. My buddy brought over a vacuum tester and the only line that recorded a vacuum leak was the one going to my factory boost gauge/aftermarket gauge. We capped off the line and I thought I was golden but the power still wasn't there. I just popped all 1000 of those f#%@ing push tabs off the plastic shield under the engine to check the lower intercooler pipe cause that was my last solution. Everything worked perfectly for 6 days then all of a sudden this happens. I would highly appreciate any info cause this is driving my crazy. Thanks
I put the buschur small battery kit in my car the same day the problem arose so the ecu would have been reset then and no I haven't checked the spark plugs but I guess I'll give it a try.
Wait, you said the MBC was installed "next" after the boost gauge, but then later you said it wasn't installed? Can you clear that up? Are you saying that you installed the boost gauge, but randomly forgot the MBC and then later the boost was tapering more than before?
I can tell you one thing that you were never at any point only tapering 1psi, and especially not if you were running on the stock boost system, because the forced taper is drastic. A flash CAN reduce taper, but not to 1psi - it's just not physically possible. If you did have the MBC installed, then again the taper is reduced, but not to 1psi. We have about a mandatory 3psi taper from 3500 to 7000rpm as proven by MAP sensor logs (can't really go by the gauge). However, if you started to observe a much more drastic taper, then the pure numbers are less important than the noticable difference.
There is nothing I know of that would suddenly cause boost to taper more than before, but my first suggestion would have been a boost leak test. You said your friend came over and performed one? Can you tell me exactly what he did, because I'd hate it if I overlooked this step and it turns out that he didn't do a proper test. The plugs would have nothing to do with the boost taper - if they were fouled, you'd feel the car sputter hard every time you hit peak boost. If you did a proper boost leak test up to 25psi and had 0 leaks other than the boost gauge line, then I'd be very surprised. I have encountered VERY FEW modded Evos that didn't have multiple boost leaks - small, but noticable when doing the test. First time I tested my own car, I had 5 leaks...
The day before this problem began I updated my vehicle profile because the mbc was going to be installed the next day but it never was, due to trying to figure out what had happened. I was clearing up TSIBER RYDERs question and I thought he meant if I had installed the mbc which I didn't. I installed the boost gauge but didn't have time for anything else. The car boosted to 21 then dropped down to 20 as the revs climbed I believe what you say but thats what the gauge said, not sure if it mattered which gear I was in.
When I really thought about the plugs idea it just couldn't be the problem because the car just hit 4,000 miles. When my buddy came over he tested the bov vacuum line and the other ones that we could get to without busting out a bunch of tools (it was dark and raining). I have no idea what psi he tested it at but I'll keep your suggestion in mind. The only ones that we didn't vacuum test were the ones going from the factory boost controler/wastgate/ turbo. Yesterday we pulled the factory intake and inspected the lines by eye and it looked fine. I plan on testing those lines as welljust to be sure.
Wait, how do you test individual lines? That's not how a boost leak test works. You need to build or buy a boost leak tester and pressurize the entire boost system in order to find boost leaks. You remove the intake and attach this device directly to the turbo inlet. You then apply pressurized air to the closed system up to 25psi. You likely won't reach 25psi the first time, because there will be one or more leaks somewhere. This is when you take your handy spray bottle with soapy water and spray wherever you hear noises in order to find the leak(s).
This needs to be done next. I need to make a tech write-up on here with the directions. I used to use the writeup on vfaq.com, but it has been down recently, so I should make my own for EvoTuners...
Wait, how do you test individual lines? That's not how a boost leak test works. You need to build or buy a boost leak tester and pressurize the entire boost system in order to find boost leaks. You remove the intake and attach this device directly to the turbo inlet. You then apply pressurized air to the closed system up to 25psi. You likely won't reach 25psi the first time, because there will be one or more leaks somewhere. This is when you take your handy spray bottle with soapy water and spray wherever you hear noises in order to find the leak(s).
This needs to be done next. I need to make a tech write-up on here with the directions. I used to use the writeup on vfaq.com, but it has been down recently, so I should make my own for EvoTuners...
It sounds like the first "mod" anyone with one of these cars should do is a boost leak test. I am learning about the Evo as I will be searching for one next spring. I say this because in my trolling/learning in the forums I am amazed at the number of people that are convinced it's not a boost leak and then low and behold what do yo know??? They find a boost leak and life is good. Doesn't someone sell a t-bolt kit for these cars? I'm thinking a boost leak tester and some new clamps all around will be one of the first things I do upon purchasing an Evo. When dealing with forced induction the path of least resistance needs to be the intake/cylinder head, not a poor seal around a clamp/coupling.
One thing you all seem to be forgetting is that an EVO IX will pull back boost if you start flowing significantly more air through the MAF sensor than a stock EVO IX flows. Reducing boost pressure is pretty much a standard response from the EVO IX ECU for a free flowing exhaust system. This is why a boost controller is more of a "gota have it" for the IX than it is for the VIII.
Keith
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EVO 11.53 @ 123.37, Black WRX Wagon 13.62 @ 99.24
I assume you specified that you would be using a boost controller when you sent your ECU off to be programed though.... so the tunner would not make corrections to the ECU's boost map if it is not going to be used to control boost by the customer.
Keith
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EVO 11.53 @ 123.37, Black WRX Wagon 13.62 @ 99.24
Who did the flash?.....Also I agree the pressure test is a must on the whole system-amazing how many little lines are not sealed 100%. --What mbc are you using also?
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