|
Xoutpost server transfer and maintenance is occurring.... |
Xoutpost is currently undergoing a planned server migration.... stay tuned for new developments.... sincerely, the management |
|
LinkBack | Thread Tools | Display Modes |
#1
|
|||
|
|||
P0171 & P0174 Lean codes with a twist!
Over the last few weeks it’s come back. I’ve checked all the obvious locations and everything looks really good and not very dry rotted. What has me confused is that the car is actually running really well. Power seems normal, it accelerates normal, and isn’t really acting like there is a vacuum leak. No hard starts or misfires. I’ve reset the codes a few times just to see if they pop back up and they consistently come back 45 min after resetting, without fail. The light typically illuminates while I’m driving at 70mph on the highway. Is there anything obvious that this could be attributed to? Since the car is running well and I’m not noticing any real MPG changes I’m kinda baffled as to what it could be. My current plan is to: • Replace DISA o-ring (it wasn’t super hard to pull the DISA unit when removing it for the intake replacement) • Test CCV and see if it needs to be replaced (it was replaced along with the valve cover gaskets 30k miles ago) • Clean MAF (possible replacement) • Pre-Cat 02 Sensors replaced • Fuel Injector Cleaner • Fuel Filter replaced • Fuel Pump (possible replacement) Anything else you’d address? What order would you go in to solve the problem? |
Sponsored Links | |
|
#2
|
|||
|
|||
I'd first check the boot again. Maybe it was not clamped on perfectly - which would be a pretty easy thing to not get right.
Or maybe it tore again. Really. When I got one of those codes, I quickly found the boot with about a 1" tear in it. Seeing records from the PO, it was replaced only 25k miles earlier (and I belive that due to the low wear on it in general), and it was a genuine BMW part too. I don't know, but it seems that if things are clamped in place skewed, there may be some stress on it that would make it tear faster than usual ??? So maybe that's your twist?
__________________
2001 X5 3.0i, 203k miles, AT, owned since 2014 |
#3
|
|||
|
|||
Check your ccv hoses, too, particularly the one that goes to the dipstick tube. Some are buried and hard to see, but they're also a source of vacuum leaks that don't pop the codes right away. Failing the visual check, get your hands on a smoke tester, which will out the source of the leak quickly.
__________________
2012 xDrive35d 2001 BMW X5 3.0i 5MT and two 1987 Corvettes - Callaway Twin Turbo and Guldstrand Grand Sport 80 Block Tester |
#4
|
||||
|
||||
Could be that the fuel pump is not able to keep up with the demand of the engine when the truck is driven at 70 mph for an extended amount of time. I would look at the fuel trim when you are driving at 70 mph. You can use a scanning app such as obd fusion to log fuel trims data while driving. log the speed while you are logging fuel trim so you can see what the fuel trims are for a given speed.
__________________
2006 Infiniti G35 2001 BMW 3.0I E53 X5 Build date 08/2000 SOLD Lotus Europa 1970 Destroyed by fire Lotus Europa 1970 S2 Renault Powered Lotus Type 52 1970 Twincam Webers Powered PORSCHE 911 Targa 1982 The Garage Queen Audi Avant donated to Kars for Kids BMW 525IT Sold Audi 4000CS Quattro Sold Jensen Healey Lotus Powered Sold Opel 1900 Sold Triumph Spitfire 1971 Sold Triumph Spitfire 1968 Sold Plymouth "Cuda" 340 Six pack SOLD |
#5
|
|||
|
|||
Pull apart this connection (red circle) and make sure you still have the large, ribbed, O-ring on the MAF exit side. A lot of times, it gets crunched up and stuffed in there or falls off which leaves a gap for unmetered air to enter causing the lean code on both banks. If this is the culprit, give the plastic intake tube a spritz inside with dry silicone spray to ease it over the O-ring forming a tight seal
|
#6
|
|||
|
|||
Quote:
|
#7
|
||||
|
||||
Quote:
__________________
2006 Infiniti G35 2001 BMW 3.0I E53 X5 Build date 08/2000 SOLD Lotus Europa 1970 Destroyed by fire Lotus Europa 1970 S2 Renault Powered Lotus Type 52 1970 Twincam Webers Powered PORSCHE 911 Targa 1982 The Garage Queen Audi Avant donated to Kars for Kids BMW 525IT Sold Audi 4000CS Quattro Sold Jensen Healey Lotus Powered Sold Opel 1900 Sold Triumph Spitfire 1971 Sold Triumph Spitfire 1968 Sold Plymouth "Cuda" 340 Six pack SOLD |
Bookmarks |
Thread Tools | |
Display Modes | |
|
|
|