mustang_09

So i have a 2002 Mustang gt with 100,xxx miles on it. I was on the coast and i pulled out of a parking lot and redlined it from 1st to 2nd and then 2nd to 3rd, and then slowed down to the speed limit in 3rd. I pulled over moments later to get out and talk to someone. When i returned to my car my service engine light was on. I went to auto zone and they pulled these codes. P1130 (O2 sensor transition-fuel trim at its limit). P 1150 (Lack of O2 switches-bank 1 sensor 1.) P 0171 (Fuel trim bank 1 condition.) P0174 (Fuel trim bank 2 condition.) The car didnt seam like it was acting any diff at this point. When i returned home i did some research and found i should clean the MAF sensor. So i did... and the car didnt seam to act any diff. after that. Well a few day later i was pulling out of a parking lot with a steep decline and as i pulled onto the road the car bogged down and showed the tire spin light for a second. So i pulled back in the same parking lot and checked my fluids. I pulled back out from the same parking lot and it bogged again. I just keep going this time and it didnt bog again the rest of the trip home (15 min. trip) Then i noticed the idle was acting a little diff. It would drop to around 500 rpms then back up when i reached a stop light. Any ideas of what might have happend? How to get this fixed? Thanks guys.
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cliffyk

My first guess would be low fuel pressure from a clogged filter, bad FRPS (Fuel Rail Pressure Sensor), bad fuel pump control module or the pump itself--in ascending order of PITA.

Monitor the pressure at the fuel rail to check this theory out...

mustang_09

there is a hose that connects to the right of the IAC on the throttle body and goes to the valve cover on the pass side. It has a ruber flex hose in the middle to connect the two solide plastic hoses and the ruber hose has two cracks in it that could be leaking air into the system. Would that be the reason for the codes saying to rich or lean?

cliffyk

That would do it...

It would have helped to have known about this in your first posting as one would think simple and obvious things like that would have already been tended to...

mustang_09

I didnt do any work under the hood other than cleaning the MAF sensor untill a few hours ago. If i knew that hose had a crack in it i would have stated it in the first post. I couldnt see any crack on the hose untill i took it off to change my plugs and clean my throttle body. Sorry for the confusion, and thanks for all the information.

cliffyk

No problem. Our cars are very sensitive to unmetered air insertions, I.e. air that has not been passed through the MAF and measured--first thing to check when any lean condition pops up...

mustang_09

So i cleaned the throttle body, and IAC. Then i replaced the spark plugs with motorcraft platinum plugs. I replaced that hose with a new hose and then i went to auto zone to have them run the car for codes to see if the hose fixed the problem. Well it still shows the lean codes and now its saying there are multiple misfires. Would the car still show the lean code even if i fixed the problem? What would cause multiple misfires after changing plugs?

cliffyk

The codes needs to be reset using a scan tool:

mustang_09

Well i unplugged my battery to reset everything, and took it for a spin. It drove alot smoother and had no service engine light come on. I hope i got everything fixed and can put this one behind me. Thanks again.