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Ted G.
Ted G., ASE Certified Technician
Category: Car
Satisfied Customers: 6089
Experience:  20 years auto repair experience, ASE Master Tech, Mechanical Failure consultant, Expert Witness
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bmw x5 code po171 and po174

Resolved Question:

i have a 2003 bmw x5 3.0l pulled codes po171 po174 and p1347. cleaned mass air flow sensor and replaced all six plugs. Car would run ok for about 15 min, then will toss up po171 and po 174 still running ok then will start miss firing po1347. can you tell me if the po 171 and 174 causing the miss fire and do you recommend that i replaced the maf sensor.
Submitted: 8 years ago.
Category: Car
Expert:  Ted G. replied 8 years ago.
First thing to do is check all the vacuum hoses and the hoses between the MAF and the engine. Pay particular attention to those as they develop splits along the seams. Then check the intake gasket for vacuum leaks (spray induction cleaner or WD40 along there and see if it effects idle). If you are convinced that there are no vacuum leaks, then a mass airflow sensor will likely fix the problem.
Customer: replied 8 years ago.
Reply to Ted G.'s Post: do you think the 171 and 174 bank 1 and 2 leaning out causing the miss fire 1347
Expert:  Ted G. replied 8 years ago.
It is quite possible, low speed lean trim can cause misfiring and the first repair needs to be the lean codes.
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