Just took my truck to the shop for P0171 and P0174 codes.They replaced the fuel pressure regulator, and said all was good when I picked it up. The CEL came back on the same day within about 30 miles. Took it back in for the same codes and they do not know what the problem is. They are thinking may the fuel pump or MAF sensor. They said the fuel pressure was good from the pump so I am not sure that is the problem. They looked over all the vacuum lines and all looked ok. Just had a tune up and replaced the front 2 O2 sensors within the last 6 months.
What else could be checked that may have been missed???

Thanks

 

You might try cleaning the mass air flow sensor with a trottle body cleaner. Also look for a vacuum leak. If you haven,t replaced the pvc valve thats good prevenative maintance. I like to get mine from ford. good luck

 

One easy thing to check is if they reset the computer after replacing the parts. Just take off the battery cable(s) (maybe clean them while they're off) and wait a little then reconnect them. This will reset the computer. If they didn't reset it and the computer was compensating by running leaner to draw more air through a dirty filter (for example) you have to reset it to return it's operation back to normal and if it gives the codes then - you didn't get the problem. I agree - it's very likely not the fuel pressure (it's too easily tested and I'm sure they did). Could be dirty injectors not pushing out enough fuel and thus running it lean. What year is it and does it have a fuel pressure regulator? I thought the pressure was regulated at the pump. I guess I should study injection systems better to be more positive but I remember a vacuum operated part on the fuel rail (could be it). A fuel filter could also do it. The pressure might read OK and when you throttle the gas if the filter's restricted the pump won't be able to keep up the pressure which indicates a bad filter. Out of tank fuel filters should be replaced every 50,000 miles or so. I agree - cleaning or replacing the MAF sensor could be a good idea if all the easy options are exhausted.

 

Just picked up the truck after having it in the shop again to check the Lean Codes I am having. They checked everything again but didn't find any issues. They suggested that I take it to the dealer to have a Computer Reflash done. So the question is what does this do for me? They claim it will reset everything but I want to know that I am not just throwing money at something that I don't need to.

Is this a good thing to do and is the dealer the only one that can do it correctly?

Thanks, Kerwin

 

It is good if you can't reset it yourself. Maybe look online for info. on resetting it yourself 1st. If not - the dealer really shouldn't charge much for it - but call and see first (to be sure).

 

The dealer charges 85.00 to do a Computer Reflash and said it takes about an hour to hour and a half to do. But not knowing whatdoing this does forme, I want tomake sure I am not paying for something that I really don't need. Would pulling the battery cable off for a bit cause the computer to reset itself better than clearing the codes with a code reader?

 

First - a code reader doesn't normally clear codes (it reads them)- usually only a factory computer system can do that. Second - for Free versus $85 I'd try it myself first. If your computer has permanent memory storage - taking the cables off will not help though. It's possible it has it's own internal backup battery. Maybe you could go to a couple search engines and find details on manually resetting (I'm sure the mechanics had a back-up plan).

 

check on the back of the throttle body housing this is a common problem follow the pcv hose back the elbow usually is collasped