99 4.0 head scratcher...

[papasmurfor9]

I now have a 1999 4x4 Supercab Ranger. I've on the forum before with my 93 ranger i sold but i forgot my username. A few weeks ago the 99 truck became very hard to get started and had no power. It was running very rough when it did start. I cleaned the MAF sensor and changed the fuel filter. It did not help. We checked fuel pressure and determined it only had around 10lbs and thus needed a new fuel pump. The one on it was only about a yr old. We tried that and it helped some but it still would not start very well but had some power back. Then we changed fuel pressure regulators to the old one and that fixed the starting problem. I think it then had 60lbs of fuel pressure. Now mostly after a long drive like on the interstate when it gets good and hot if I stop like when exiting Interstate-55 the engine will start idling really rough and completely stall. I can start it right back and it will go…sometimes fine and sometime missing/sputtering. I'm gettng the following codes...452 (fuel tank pressure sensor condition) , 171 (fuel trim bank 1 condition), and 174 (fuel trim bank 2 condition).

 

[papasmurfor9]

Also i know i have a vacumn leak because sometimes the ac will blow only out of defrost vents like when going up hill. I haven't been able to find the leak. I even used a smoke machine. could this be related to my problems?

 

[Earl43P]

Yes.

http://www.explorerforum.com/forums/showthread.php?t=171819


Welcome to The Ranger Station!

 

[papasmurfor9]

Thanks. That is helpful. I sprayed some carb cleaner around my intake yesterday and my engine definitely acted differently. Apparently their is a vacuum leak associated with those gaskets. Being a shade tree mechanic I don't believe this a job i want to tackle. I have friends that own a small ford dealership. I will talk to them about fixing it and then update the forum as to the results.

 

[Earl43P]

I'm shade-tree myself and I have done those gaskets on a 99 Explorer, SOHC.

You can do it in an afternooon, easily.
Do yourself a favor and replace the coolant thermostat while doing those gaskets/seals.

 

[RonD]

I wouldn't rule out Catalytic converter or exhaust problems, restricted exhaust flow can cause loss of power and temp plug fouling, i.e. rough idle.
If you can remove the Cat bolts and wire it up out of the way you can then do a test drive and see if restricted exhaust is the problem or part of the problem

 

[racinwarrior]

I wouldn't rule out Catalytic converter or exhaust problems, restricted exhaust flow can cause loss of power and temp plug fouling, i.e. rough idle.
If you can remove the Cat bolts and wire it up out of the way you can then do a test drive and see if restricted exhaust is the problem or part of the problem

clogged cats would be a constant problem, not an intermittent one as he is experiencing