2004 manual.70,000 mi, both o2 sensors and maf are 4000 mi old, new engine soon after. Bone stock, no vac leaks. I've been dealing with this for 6 months off and on. It started with new maf didn't fix anything than a remain engine no cell for a month than bam!!! back on same p0171 lean bank 1. Then they ran fuel enjector cleaner in it three times,nothing. then changed both o2 sensors and nothing since. Then I brought it in because it was idling rough and i thought it was mis fireing i could hear a mica sound in any gear at lower rpms. say third gear at 30 mph at 3 grand.they did an engine decarb and said it was probly carbed up from the lean code it ran. Seemed fine for a few months but still hearing that mica sound from time to time. And the cat was thinking glowing a bit around the front o2 sensor when I got home tonight Then today its back p0171 of death! Any insight would be appreciated!! Thanks.

 

Likely a vac leak ...often as easy as the VFAD nipple leaking.....I would use a smoke tester on the intake and see what you get for leaks

 

Thanks for the quick response. But as I said no leaks already did a vacuum test all good there you think a miss fire could cause a lean code?

 

Went to start her up this morning it was pretty cold out and had to crank longer than normal and I herd a little chirp right before she started.. I let it warm up when I came back out she was idling real rough I could hear the hood rattling a little. And so was the stearng wheel and shifter.

 

shaking usually means imbalance, imbalance usually means one rotor isn't functioning properly. Remove your spark plugs and take a look. You also mention that your cat was glowing, so it really sounds like you are carbing up the engine real bad. Remove and clean your spark plugs, and drop the cat to make sure it isn't on its way out.

 

Thanks .soror I was thinking the same thing I can't bring it in until Monday. The cell came on after I had been driving in traffic for a couple hrs then this morning it was on when I started the car got gas got in and it was off. You think when the car gets hot its mis firing. I have no tools to check out the plugs and coils with maybe I can get a local ti help out.

 

if it was misfiring you would get a flashing cel for that. so most likely not misfiring. I would assume you are getting a clogged cat.

 

I guess it sounds more like detonation than misfire. Maybe I worded that wrong. But i hetd you can have a slight misfire with out even theowing a cel. Last time mazda said the cat was at proper temp after they drove it. But I thought the same its like pulling teeth to get them to pull the cat down and look at it.

 

what kind of diagnostic tool are you using? Cobb?

anyway to monitor afr?

 

Just stoles buy advanced auto and used what they have but I can stop buy and see if it has that option

 

Used not stoles. Fat fingers sorry! Anything else I should write down

 

Didn't make it by advanced auto but will post the afr readings in the morning and going to take her down to mazda on monday.

 

Update........Still dealing with this.... mazda is doing some work to my fuel injectors... but the tech didn't seem like he was convinced that was the issue and he said my coils were testing good But had a feeling they are good until I drive for over an hour than they over heat going to order a .BHR. when mazda tells me that its still not fixed.