Boost leak vs vaccuum leak ???
May 20, 2005, 07:05 AM
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Boost leak vs vaccuum leak ???
Is the symtoms of a boost leak different from a vaccuum leak??
Is the narrowband a/f reading on the apexi TT reading useful? During cold start-up my rpm fluctuates around 1500 rpm. The a/f reading on the apexi TT shows 18, 17, 16 back to 18 etc. After the car warms up the a/f comes to around 14.3 and remains around there. During cruising it's around 14.3 also. When I go WOT it holds 20psi till redline but car doesn't pull as much as before. Is this a sign of vaccuum leak?
I have BR stage 4 and car have been custom dynoflash twice. Currently car does not pull as hard as before and off boost response as well as on boost seems to be more laggy as compare to before. Boost leak? exhaust leak? second flash not as good as first flash? I tried using both a 1g and recirculating turbo xs rfl bov and the car pulls harder with the turbo xs bov. Tried boost leak twice and could only get the pressure to 15psi and was able to fix a slight leak but car still doesn't feel the same. Please help.
If I dyno the car would that help detect my problem? I don't mind paying $$$ to get the problem fix but would hate to spend $$$ and find out that problem still exist.
Is the narrowband a/f reading on the apexi TT reading useful? During cold start-up my rpm fluctuates around 1500 rpm. The a/f reading on the apexi TT shows 18, 17, 16 back to 18 etc. After the car warms up the a/f comes to around 14.3 and remains around there. During cruising it's around 14.3 also. When I go WOT it holds 20psi till redline but car doesn't pull as much as before. Is this a sign of vaccuum leak?
I have BR stage 4 and car have been custom dynoflash twice. Currently car does not pull as hard as before and off boost response as well as on boost seems to be more laggy as compare to before. Boost leak? exhaust leak? second flash not as good as first flash? I tried using both a 1g and recirculating turbo xs rfl bov and the car pulls harder with the turbo xs bov. Tried boost leak twice and could only get the pressure to 15psi and was able to fix a slight leak but car still doesn't feel the same. Please help.
If I dyno the car would that help detect my problem? I don't mind paying $$$ to get the problem fix but would hate to spend $$$ and find out that problem still exist.
Last edited by GOKOU; May 20, 2005 at 07:13 AM.
May 20, 2005, 12:14 PM
#3
Well... think about this one logically 
If you have a boost leak you therefore obviously have a vacuum leak. It is impossible to have one without the other. If it leaks are one way, it will leak it the other way. If you have a decent boost leak than yes, your car will get laggier and less effiecient. Think about this.. the boost controller is set to open the wastegate at say 20psi. It will open it at that. If you leak half the air out a hole somewhere, the turbo needs to push much more air to get it/keep it there. Therefore making it laggier and less efficient. If you have an exhaust leak it is the same idea... your engine will have to produce much more exhaust to spool the turbo because some of the gasses are escaping before it hits the turbo (It also depends where the leak is). Pressure test your intake system and look for exhaust leaks (Mainly before the turbo).
If you have a boost leak you therefore obviously have a vacuum leak. It is impossible to have one without the other. If it leaks are one way, it will leak it the other way. If you have a decent boost leak than yes, your car will get laggier and less effiecient. Think about this.. the boost controller is set to open the wastegate at say 20psi. It will open it at that. If you leak half the air out a hole somewhere, the turbo needs to push much more air to get it/keep it there. Therefore making it laggier and less efficient. If you have an exhaust leak it is the same idea... your engine will have to produce much more exhaust to spool the turbo because some of the gasses are escaping before it hits the turbo (It also depends where the leak is). Pressure test your intake system and look for exhaust leaks (Mainly before the turbo).
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