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Old 11-07-2010, 01:55 PM
The B4000 The B4000 is offline
Learning to use the forums
Join Date: Nov 2010
Posts: 1
Default Re: If you have an 01+ 4.0 with lean codes (PO171 and/or PO174) look here!

To the OP-you are the King!! Thanks for posting all the great pics. I am not very skilled in the mechanical department, but this was my problem as well and your step-by step solution was a Godsend as I was about to spend about $300 on a new MAF sensor.

I have an '03 Mazda B4000 and about 2 weeks ago the CEL came on. Took it in to the mechanic, who replaced the fuel filter (which it needed anyways). The first time around he did the smoke test and found no vacuum leak as he was certain there would be a leak somewhere. He also believed all the O2 sensors were fine and cleaned the MAF sensor as well, which led him to the fuel filter. Within a day or two, the CEL returned when my wife was driving it. The second time around I had it back to him, he still could not find the issue; he is also a very reputable mechanic where I live so he cleared the codes and the next day, CEL on. He advised me if the light came back on, which it would, it probably was the MAF sensor going. The truck was running fine-no misses, stalls, hisses, lack/loss of power or anything. He had told me what the codes were and with a little help from good old Google I found this site. This morning, I found the problem (same as noted above) as there is 3/4" gash on the topside of this infamous elbow. I replaced it with braided heater hose from NAPA ($1.69/ft for the high end stuff) as per the OP's advice and in about 10 minutes, I had replaced it. I followed all the steps as the OP suggested to do, then took it for about a 20 mile test drive and no CEL.

Here is the gash in my PVC elbow; I had to cut the end closest to the throttle body as it was welded on there pretty good (the cut in the bottom edge) from years of service. Thanks again for the solution to such a simple (but annoying) fix!! Feeling pretty good about myself that I was able to fix something a mechanic with 20 years experience was unable to-haha.
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