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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E39 (1997 - 2003)

E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 05-09-2013, 08:36 AM
iceman4169 iceman4169 is offline
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Location: San Diego California
 
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Mein Auto: 1999 540i
Not enough Boost?

Hey guys on my 99 540i turbo theres something im a bit concerned about. First gear takes off like a rocket. Then second gear isnt as strong at all neither is third. Is this because of my transmission slipping? Or am i just not pushing enough. Its at 5psi at the moment but capable of much more then that. Also a question is it because the car is sucking in more air then the turbo can produce after second gear? Is this a possibility? i barely run 5 its at like 4.5. Any thoughts would help. Just worried tranny goes out.
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  #2  
Old 05-09-2013, 10:28 AM
Dragan Dragan is offline
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Mein Auto: 2002 BMW 530i Sport 5 Spd
If the transmission was slipping, the revs would surge and you'd have no forward propulsion with the throttle pedal applied.
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Last edited by Dragan; 05-09-2013 at 10:30 AM.
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Old 05-09-2013, 11:02 AM
iceman4169 iceman4169 is offline
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I believe the guy put in the wrong fluid. Im taking it to BMW to have it done correctly just to make sure thats not a factor. Any knowledge on the second half of it? Is my turbos boost level equal or less than the amount the engine would suck at higher speeds?
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Old 05-09-2013, 11:11 AM
Dragan Dragan is offline
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Mein Auto: 2002 BMW 530i Sport 5 Spd
Quote:
Originally Posted by iceman4169 View Post
Is my turbos boost level equal or less than the amount the engine would suck at higher speeds?
This is probably something you should've looked into prior to installing an aftermarket turbo setup on your car. Boost level, which is the maximum amount of allowable pressure in the intake manifold before the relief valve is actuated, is measured in pressure and "the amount the engine would suck" would be considered a volumetric flow rate which is measured by the mass air flow (MAF) sensor. They're two different parameters so I'm not exactly sure what you're asking. I'm also not familiar with what is and isn't OEM on your car so my knowledge and assistance may be limited.

Also, what do you mean by "higher speeds"? Are we talking engine speed or vehicle speed?
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2002 530i Sport Package 5-speed
Style 42s for summer
Style 29s for winter
CDV delete
Skibag retrofit
G.A.S. DISA Valve Repair Kit
G.A.S. 1.2 Bar Expansion Tank Cap
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  #5  
Old 05-09-2013, 07:06 PM
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Fudman Fudman is offline
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Quote:
Originally Posted by iceman4169 View Post
Also a question is it because the car is sucking in more air then the turbo can produce after second gear? Is this a possibility?
Absolutely no. The engine sucks in air at ambient pressure. The turbo, when spinning, increases inlet air pressure (forced induction) and subsequent volumetric efficiency. Unless your turbo is not turning and blocking airflow (which it is not since it works in 1st gear), that is not the reason for your problem.
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Old 05-11-2013, 02:16 PM
iceman4169 iceman4169 is offline
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Mein Auto: 1999 540i
Thank you for your replies. I believe I've figured out the problem. Its the fuel not the air at all. To start an e39 your injectors let off a certain amount of fuel. When I installed the bigger injectors it took ten minutes for the car to start. Medium injectors were put in but still didnt work right. So i bought another electric device that will bypass the computer. Adding 2 more injectors right after the intercooler. These injectors will only start pumping fuel when the bypass sees that my car has reached a certain boost pressure. Then tuning it as well is something else. Ive already fabricated this piece. It will be installed monday. Its been a hell of a project. Thank God it isnt transmission though. I really appreciate all the advice thats been given along the way. Thank you guys. Still open to any opinions.
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