04 bmw x3 need help hard starts and po172 code

ss67ls · 10-15-2020, 11:59 AM

hello i have a 04 bmw x3 2.5i it is hard to start in the mornings and after it sits for a hour to get it started i have to give it gas then it starts stumbles runs rough for a few then runs great.have replaced fuel pump no change .the other problem is code po172 have been fighting this code .i have smoke tested no leaks found,replaced spark plugs and coils,replaced both upstream 02 sensors and replaced MAF sensor .i cannot figure out what is going on any help would be grateful thank you

CapeRanger · 10-20-2020, 12:51 PM

I chased this one down for YEARS. Finally fixed it after watching these two vids. Secret of Engine Problem Diagnosis- Fuel Trims Pt.1 and Pt. 2. Linked here:

The secret is determining whether the trim is too lean at idle or in cruise. This guy explains it better than anyone else I've seen. You'll need a OBDII reader that can display real time data or transmits to a PC or phone. It will help to have a second pair of eyes to watch the data while you drive. Good luck.

10-15-2020, 11:59 AM	#1
ss67ls New Member 0 Rep 12 Posts Drives: x3 Join Date: Dec 2018 Location: seatown iTrader: (0)	04 bmw x3 need help hard starts and po172 code hello i have a 04 bmw x3 2.5i it is hard to start in the mornings and after it sits for a hour to get it started i have to give it gas then it starts stumbles runs rough for a few then runs great.have replaced fuel pump no change .the other problem is code po172 have been fighting this code .i have smoke tested no leaks found,replaced spark plugs and coils,replaced both upstream 02 sensors and replaced MAF sensor .i cannot figure out what is going on any help would be grateful thank you
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10-20-2020, 12:51 PM	#2
CapeRanger Registered 0 Rep 2 Posts Drives: '05 x3 2.5i Join Date: Nov 2010 Location: Massachusetts iTrader: (0)	Fuel Trims Troubleshooting I chased this one down for YEARS. Finally fixed it after watching these two vids. Secret of Engine Problem Diagnosis- Fuel Trims Pt.1 and Pt. 2. Linked here: The secret is determining whether the trim is too lean at idle or in cruise. This guy explains it better than anyone else I've seen. You'll need a OBDII reader that can display real time data or transmits to a PC or phone. It will help to have a second pair of eyes to watch the data while you drive. Good luck.
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