Car not hitting full boost?
05-25-2004, 07:08 AM
#1
Car not hitting full boost?
My setup is a 1990 CRX, DRAG III kit, DIY MBC, DeltaGate 7 psi spring, Open DP, Hondata s200b. The wastegate opens at 5 psi, I used the MBC to turn it up to 10 psi. Then one night I noticed it was only boosting 5 psi. I turned up the MBC, stayed at 5 psi. I tightened down all couplers and still only 5 psi. No holes or rips in the couplers that I can see. Intercooler piping is fine also. The BOV is a HKS SSQV, bolt on the back is tightened down all the way. I dont think this could be the problem b/c it has always been like this. I just took the filter off the turbo and tried that, it hit 7 psi, but later than usual, it hit 5 psi, then creeped up to 7 psi around 4500 rpm, usually hit full boost around 3600 rpm. Any advide or help? thanks. I didnt mess with anything or even touch anything, it just happened.
05-25-2004, 07:59 AM
#3
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Re: (RotiEatter)
Sound like a intercooler piping or BOV leak. Double and triple check everything. Check all your boost controller lines, if you have access to another wastegate try that
05-25-2004, 11:49 AM
#5
Re: (RotiEatter)
Just went for a drive, and realized that when i would get near 0 on my boost gauge I would usually hear the BOV flutter. So I took it 2-3 psi, didnt hear the bov at all. THe vacuum line for the BOV looks fine. Is it possibly the little inline-filter for the HKS BOV? THe bolt on the back is all the way tight on the BOV and it has always been like that. Thanks
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05-30-2004, 12:57 PM
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Re: (RotiEatter)
does the car feel any different like it lost positive manifold pressure or is the reading on the boost gauge the only indication it's not boosting how it was before?
06-01-2004, 03:42 PM
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Re: (RotiEatter)
I got the same problem and the same kit with some other upgrades. I still havent been able to figure it out. So far I have beend advised for boost controller, exhaust back pressure, leaks in piping or vacuum leak, or exhaust side of the turbo. You figure it out, let me know, and Ill do the same hehe
06-01-2004, 04:43 PM
#16
Re: (95GSRTT)
have you tried anything to fix it yet? I know its not my boost controller because it still only boosted 5 psi with the MBC to wastegate vacuum line un-hooked. I have no exhaust back pressure since I dont have an exhaust. I think its either the turbo or the wastegate but I dont understand why the BOV isn't going off in 2-3 psi though.
06-02-2004, 01:18 PM
#17
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Re: (RotiEatter)
Ive done back pressure test, Changed out so it went straight from the housing to the wastegate. Did a ghetto rig on trying to find boost leak. Will do a better job of one this next week. put in different spring to wastegate. Only way the wastegate would open was with no spring, but thats b/c I wasnt hitting max boost like you are. Only thing I can think of is a leak really. My BOV does flutter, but you can also hear it at any boost level when you let off.
I checked the intakeside of the turbo and no shaft play and spun freely. Only thing I can think of wrong with the turbo is that the exhaust side turbine has something wrong with it, so it cant spin past 6. But I made great power at 6 psi up to 6 psi so I doubt that is it.
Im getting a new cat and 3" exhaust this next week or so, but doubt that will do anything. Even though another guy did say he wasnt able to go up past 8 psi until he got a bigger exhaust. Mine is only 2 1/4.
What are your compression numbers, and are you just running straight from the downpipe?
If I were you I would count out the wastegate. If your not reaching max boost, and your spring is higher than the boost your reaching, there is no point for your wastegate to open. So it not opening is pretty much null. Its leak or exhaust.
Ill keep you updated as I spend more money lol.
Do the same for me.
I checked the intakeside of the turbo and no shaft play and spun freely. Only thing I can think of wrong with the turbo is that the exhaust side turbine has something wrong with it, so it cant spin past 6. But I made great power at 6 psi up to 6 psi so I doubt that is it.
Im getting a new cat and 3" exhaust this next week or so, but doubt that will do anything. Even though another guy did say he wasnt able to go up past 8 psi until he got a bigger exhaust. Mine is only 2 1/4.
What are your compression numbers, and are you just running straight from the downpipe?
If I were you I would count out the wastegate. If your not reaching max boost, and your spring is higher than the boost your reaching, there is no point for your wastegate to open. So it not opening is pretty much null. Its leak or exhaust.
Ill keep you updated as I spend more money lol.
Do the same for me.
06-02-2004, 01:21 PM
#18
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Re: (95GSRTT)
Also try going straight from the turbine housing to the wastegate. Bypass the mbc all together. Your spring shouldnt be more than 9 lbs so if you do get more than 5, it wont go past 9. That will indicate whether its the controllers fault or not. Im betting more and more on a leak some where. Been diagnosing it for like 2 weeks now.
06-02-2004, 05:14 PM
#19
Re: (95GSRTT)
Yeah, I am running open downpipe. I think it maybe a BOV leak, or maybe it is the BOV itself, because I cant hear it anywhere below 5psi, and at 5 psi its not as loud as it used to be. I know its not a leak in my intercooler piping or couplers because I took them off and checked them. I can hear the wastegate opening so I doubt it is that also. My compression numbers are 185 psi on all cylinders. I also have no shaft play on the intake side of the turbo. I am out of town right now so I am not going to be able to work on it for a little while. I just really hope it isnt the turbo because I really dont have the money for another one. It is possible it is the turbo? It spools up fine and hits 5 psi around 3500 rpms. It doesnt smoke at all, which makes me think it isnt the turbo. Does anyone know if it is possible it is infact the turbo?
06-04-2004, 12:36 PM
#21
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Re: Car not hitting full boost? (RotiEatter)
I think you might be right on the BOV. Last night on my way home I was running the car all the way up to redline, and around 5k, I start to hear some fluttering around the BOV that sounds like air is escaping, instead of holding it in. Im gonna check it out this weekend and see what I can find. Also just ordered a Profec B II so we shall see if thats the problem or not.
06-04-2004, 01:17 PM
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Re: Car not hitting full boost? (95GSRTT)
I actually think the reason why im only hitting 6psi is because my bov is leaking/or too loose. Im going to check my lines this weekend and tighten it up and see if I can reach 7.5psi which is where I should be at with my spring in my wastegate
06-04-2004, 05:49 PM
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Re: Car not hitting full boost? (RotiEatter)
yo, what is ure actuator set at, bypass ure mbc and see if it hits thats boost, if so the spring in the mbc is messed up or not sensitive enough, i had the same problem, i cant set it past 10 pounds, it hits 10 or 15, gotta buy a new one