the first thing you should have checked for and im suprised noone else has said this are vacuum leaks. it is common for the 90 degree elbow on the bottom front of the intake to leak, and also the ones back behind the pcv valve. change the pcv valve while your at it. if you cant hear the hissing sound of the leak, spray some starting fluid around some of the vacuum lines and if the engine revs, your close. and i rarely actually change the maf sensor. just take it out and spray some cleaner down in it. if the filament isnt broken, you can probably just clean it.

 

Now that you mention it, I have noticed a louder than normal hiss when I open the hood with the engine on. It is just hard for me to determine exactly where it is originating from.

 

"I wrote a lengthy response to your codes yesterday, but somehow I didn't post it. Sorry 'bout that.

The 1506 indicates that the IAC is maxing out trying to richen up the idle. The other two indicate a lean condition on both banks.

You either have a severe vacuum leak, or more likely low fuel pressure. You need to test your fuel pressure and you need to connect the gauge before starting the truck and see if it comes up right away. THEN after killing the engine watch the fuel pressure for several minutes and see if it bleeds off. This is probably not something to worry about with your particular problem, but it is being thorough. If it is bleeding off fast then you have a leak somewhere, a stuck injector or a bad check valve.

If the fuel filter hasn't been changed in awhile, just change it. If the fuel pressure is low, then you will have to find the reason for it and fix it.

If the fuel pressure looks good in every way, you need to start looking for a serious vacuum leak."


Moss,

Excuse me but the above I posted yesterday or this morning and the post before yours he was indicating that he was going to connect a vacuum gauge as the next step.



1997F150,

A good way to search for a vacuum leak, albeit an old fashioned method, is to use a piece of vacuum hose or some other flexible hose with one end stuck to your ear and the other end held in your hand to move around and listen for vacuum leaks. When I was a kid in the fifties, my Dad had an independent shop and he used the remnants of an old Stethoscope with a piece of vacuum hose at the bottom of the Y instead of the stethoscope sensor part. This way he could hear what was going on at the end of the hose while other noises were blocked out of both ears.

Might not be too high tech, but it sure works good.

Good luck,
Doc

 

OK,

I managed to get rent a vacuum pump: http://www.autozone.com/in_our_store...acuum_pump.htm

Now how do I use this thing is the question?

 

Never figured out how to use the vacuum pump, but I did check all the hoses for leaks. I sprayed water on them and used a stethoscope to try and pinpoint the hiss. No luck. The hiss seems to be coming from deep within the engine block.

Also, early this morning there was more smoke pouring out the exhaust pipe. Things are not looking good for me.

 

My 97 Expedition 5.4L was sputtering also, so I tossed on the OBD scanner from Advance auto. It was showing Codes P0171 & P0174. Bank 1&2 lean. Here it was the pcv valve tubing where it connects to the back of the intake. The rubber grommet dry rots and creates a huge vaccuum leak. Dealer part only. With Pa tax-$29.00. I hope this helps.

 

Hey, thanks for the tips. I have a '98 f150 4.2L and the CEL came on. Came up with a p0171 OBD code and the engine was running very rough at idle. Took your advice and found exactly what you described. The 90 deg. elbow on the front underside of the intake manifold was deteriorated and had a big hole in it. Replaced it and all is good. Thanks again!!

 

With P0171 & P0174 if the pcv hose does not have a leak and fix those codes, you should check the O2 sensors. I had both those codes and after replacing all 4 O2 senors they were cleared.