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 > 7 Series / 8 Series

7 Series / 8 Series
The BMW 7 series and 8 Series Forum

 
 
Thread Tools Display Modes
  #1  
Old 02-11-2010, 09:50 AM
mkrazy1 mkrazy1 is offline
Registered User
Location: Burlington, KY
 
Join Date: Jan 2010
Posts: 12
Mein Auto: 1987 MB 300D
740iL stalling/eng failsafe

On a 1999 740il with 100K, I am having problems over the last month with it going into engine fail safe mode. I initially had the dealership look at it and they said it needed a mass air flow meter and this would not necessarily fix it. It had a code for MAF out of range. I replaced the MAF and reset the codes. The same problem happened. While driving you can feel it hesitating a bit and if I take off hard, it will hesitate and then go into fail safe mode where it basically stalls. If I shut it off and restart, I can take it easy and drive it. It did set the MIL again, so I read the codes and the MAF code did not come back, but it came up with P0171 and P0174 (I think) for Bank 1 and 2 running lean. I searched for a vacuum leak and can't find any. I replaced the fuel filter (included regulator) and test drove again. It is still doing the same thing, but the MIL has not come back on yet. Any ideas? What should the fuel pressure be?

I have a OTC Genesis tool that I hooked up while I was test driving. I was monitoring the STFT readings. Is it normal for the Bank 1 and 2 sensor 2 readings to never change? They stayed at 99.2%. The Bank 1 and 2 Sensor 1 would change from 0 to + or - a small number. Is there even a sensor 2 for this?
Advertisement
  #2  
Old 02-11-2010, 10:28 AM
TxGr8White TxGr8White is offline
Sick Puppy Motorwerks
Location: Dallas
 
Join Date: Jan 2010
Posts: 132
Mein Auto: BMW 850Ci
Have you had a look at the fuel pump? My E38 740iL had this problem also and it turned out to be a faulty fuel pump. - Just a thought.
__________________

White 1993 850Ci - 251,187 miles
Black 1993 850Ci - 125,508 miles

Last edited by TxGr8White; 02-11-2010 at 10:44 AM.
  #3  
Old 02-11-2010, 11:27 AM
mkrazy1 mkrazy1 is offline
Registered User
Location: Burlington, KY
 
Join Date: Jan 2010
Posts: 12
Mein Auto: 1987 MB 300D
That is kind of where I am leaning. What should the fuel pressure be?
  #4  
Old 02-16-2010, 08:16 AM
mkrazy1 mkrazy1 is offline
Registered User
Location: Burlington, KY
 
Join Date: Jan 2010
Posts: 12
Mein Auto: 1987 MB 300D
Question Still need help and ideas...

I looked at the fuel pressure and it is a steady 52lbs at idle, 1500 and 2500 rpm. I looked at the ltft and it is 20% on bank one and 18% on bank two. I watched the stft and it seems to be staying at a positive number, as much as 10% on both banks, so now I am leaning toward a vacuum leak, but I can't hear one and using brake clean around the intake doesn't immediately show anything. I have cleared codes a few times and it does keep coming up with (if I remember right) P0429 for secondary air injection. I don't hear the air pump coming on when I first start it. Where is the fuse located? Which wire is which so I can hotwire it to validate the pump is good? Anyone have thoughts on the vacuum leak?
  #5  
Old 02-22-2010, 07:17 AM
mkrazy1 mkrazy1 is offline
Registered User
Location: Burlington, KY
 
Join Date: Jan 2010
Posts: 12
Mein Auto: 1987 MB 300D
Just to update the thread. The problem was the oil separator. I replaced it and it runs a lot better... No more hesitating or stalling when you floor it!! Still having an issue with the secondary air injection though. I'll post a new thread on that.
 

Bookmarks


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 7 Series / 8 Series
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 06:21 AM.


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