Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Please follow the links below to help get you started!

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

Reply
 
Thread Tools Display Modes
  #1  
Old 08-21-2014, 11:39 AM
00black540i 00black540i is offline
Registered User
Location: Somewhere
 
Join Date: Jan 2012
Posts: 47
Mein Auto: 1998 BMW 540i
98 540i power loss/variation

Here is the thing, my car seems to have a mind of its own when it comes to its power out put. It's a 98, 6MT 540i, pre-VANOS M62.

The symptoms are:

As I floor it, it'll come on strong, completely run out of breath(falls flat on its face) at 4k RPM and then the power will kick back in at 5k RPM, this will be very noticeable. Sometimes it's just dead all over the RPM band with no power variation to notice. At other times, the car runs like an absolute beast. I mean, it's torquey, responsive, pulls hard all the way to cut off and everything. It usually runs incredibly well when the weather is cooler. I understand that most cars run better at 60F degrees than they do at 100F, but the difference in power is way too big to just blame it on the change in weather Not to mention the obvious random power drop of at 4k RPM at times.

The car has been doing this ever since I got it. When I got the car it had melted catalytic converters, I got rid of them and the car is now straight piped. I have J bung o2 extenders, and they keep the CEL off.

Some other things I replaced in hopes of curing the issue:

CP sensor
all new Bosch o2 sensors (rockauto)
all new Bremi coils packs
I've cleaned the ICV thing
New Bosch MAF sensor

The ECU has never thrown any codes, as you can tell, I'm the guy that just throws parts at it.
Any ideas?
__________________

98 540i (6MT)
Custom intake
De-catted
DUDMD Tune

Last edited by 00black540i; 08-21-2014 at 08:34 PM. Reason: grammar
Reply With Quote
Ads by Google
  #2  
Old 08-21-2014, 02:24 PM
edjack edjack is online now
Officially Welcomed to the 'Fest
Location: San Jose, CA
 
Join Date: May 2007
Posts: 9,094
Mein Auto: '97 540i 6 speed
How old is the fuel filter?

Have you measured the fuel pressure when the symptom occurs?
__________________


Ed in San Jose '97 540i 6 speed aspensilber over aubergine leather. Build date 3/97. Golden Gate Chapter BMW CCA Nr 62319.
Reply With Quote
  #3  
Old 08-21-2014, 08:31 PM
00black540i 00black540i is offline
Registered User
Location: Somewhere
 
Join Date: Jan 2012
Posts: 47
Mein Auto: 1998 BMW 540i
Quote:
Originally Posted by edjack View Post
How old is the fuel filter?

Have you measured the fuel pressure when the symptom occurs?
I'm suspecting fuel filter as well. It's probably as old as the car is, pretty much everything but the water pump and expansion tank was OEM when I got it. It's not my first 540 so I knew what I was getting into. Except for this weird issue.

I wonder if I can measure the fuel pressure with my Torque App. Probably not, gotta look into it.
__________________

98 540i (6MT)
Custom intake
De-catted
DUDMD Tune
Reply With Quote
  #4  
Old 08-21-2014, 08:46 PM
GreenTiger GreenTiger is offline
Officially Welcomed to the 'Fest
Location: SoCal
 
Join Date: Jun 2009
Posts: 747
Mein Auto: 7/98 NonVanos 540iA
You cannot measure fuel pressure with the torque app. As far as I know, you can't really measure fuel pressure in any way on the pre vanos M62 due to a lack of schraeder valve on the fuel rail. The Vanos M62 has the valve.

No cats, brand new O2 sensors, MAF, CP sensor and coils. Hmmm. I would agree with ed and suspect a possible fuel pump issue. Could be a fuel filter issue, but I changed mine out at 155K miles and it was in excellent condition. It was also the original on the car.
__________________
"It's not about how fast you can go. Its about how fast you get to fast."
-Torque
Reply With Quote
  #5  
Old 08-22-2014, 01:27 PM
00black540i 00black540i is offline
Registered User
Location: Somewhere
 
Join Date: Jan 2012
Posts: 47
Mein Auto: 1998 BMW 540i
Quote:
Originally Posted by GreenTiger View Post
You cannot measure fuel pressure with the torque app. As far as I know, you can't really measure fuel pressure in any way on the pre vanos M62 due to a lack of schraeder valve on the fuel rail. The Vanos M62 has the valve.

No cats, brand new O2 sensors, MAF, CP sensor and coils. Hmmm. I would agree with ed and suspect a possible fuel pump issue. Could be a fuel filter issue, but I changed mine out at 155K miles and it was in excellent condition. It was also the original on the car.
I think I'll just go ahead and change it. I bought this car at an auction for a project as I missed my previous E39 540i. The car looked good inside and out, but mechanically, it wasn't taken care of. I mean I pretty much have done/will have to do every 540i related engine/drivetrain/suspension maintenance. So that brings me to my point of the previous owner perhaps using regular/mid grade gas? I don't know if it's "dirtier" or of less quality than the premium.

EDIT: Could my fuel pump just be going bad? I think I'm noticing that the car seems to run better with around 1/4 tank or less. I'll need to test this hypothesis some more to be sure. The car seems to start up weird if you shut it off in hot weather(after getting to operating temp) and then start up again with 5-15 minutes.
__________________

98 540i (6MT)
Custom intake
De-catted
DUDMD Tune

Last edited by 00black540i; 08-22-2014 at 01:33 PM. Reason: grammar
Reply With Quote
Reply

Bookmarks


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E39 (1997 - 2003)
Today's Posts Search
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



Forum Jump


All times are GMT -7. The time now is 05:20 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
© 2001-2011 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms