Mazda MPV This minivan was among the class leaders with its roomy interior and efficient powertrain.

System too lean?

  #1  
Old 04-13-2015, 11:50 AM
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Default System too lean?

Hi everyone, im new here and have been doing some research, but havn't found exactly what i am looking for. My MPV started running rough only while at idle. I immediately suspected something with the air flow such as cracked or broken hose, but after hooking up OBD II codes I got P0174, P0131, P0151, and P0171. Basically Too lean in banks 1 and 2. Did i really have 2 O2 sensors go bad at the same time, Or should I start elsewhere? I have inspected the PCV hose, and surrounding hoses but found nothing. thanks in advance.
 
  #2  
Old 04-13-2015, 12:11 PM
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Lean on both banks sounds like an MAF problem or a large vacuum leak. Clean the MAF and spray a flammable brake cleaner etc around the intake at idle. If the idle changes you found a leak. Pinch off the brake booster hose to eliminate that possibility.
 
  #3  
Old 04-14-2015, 02:11 AM
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What types of cleaners are acceptable for cleaning the MAF? I am currently stationed overseas, and i cant just go to a local auto parts store for some MAF cleaner. I have heard that rubbing alcohol might be ok?
 
  #4  
Old 04-14-2015, 05:54 AM
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i also notice that the rough idle is barely noticeable when the car is cold. It gets rough and surges once warmed up, and the issue only exists while at idle.
 
  #5  
Old 04-14-2015, 08:30 AM
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Alcohol and a cuetip should be fine for the MAF. Wet a rag with it to clean the throttle body. It probably idles higher when cold masking the problem. It could be a lot of things though. It's kinda hard to say without the van in front of me.
 
  #6  
Old 04-14-2015, 10:40 AM
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Smile

BTW thanks for your service.
 
  #7  
Old 04-29-2015, 06:04 AM
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thanks for your assistance and your support!

I have checked all the hoses and cleaned the MAF and throttle body with no results. It has now been in the shop for 2 weeks, and transfered to three different mazda dealerships who have not been able to find or correct the problem. are there certain parts i need to just order and start swapping?
 
  #8  
Old 04-29-2015, 06:12 AM
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check vac leaks in brake booster especially if it occurs with your foot on it. Mine had an internal leak. It has a large vac hose going to it from engine. Need to clamp off this hose and check idle.
 
  #9  
Old 04-29-2015, 07:00 AM
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so if there is an internal leak in the brake booster, is it repairable, or just need to replace it?
 
  #10  
Old 04-29-2015, 07:14 AM
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Originally Posted by lost cause View Post
so if there is an internal leak in the brake booster, is it repairable, or just need to replace it?
Replace. I got one from junkyard, not cheap new.
Now when i come to a stop, i put the gear in neutral and take my foot off brake and use hand brake, so hopefully it lasts longer.
 

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