1999 ex XLS vacuum leak issue?

[OKLAexplorer]

I have a 1999 Ford Explorer XLS with right at 133K miles.

Four weeks ago, I had a check engine light come on. I took it in and my uncle who works at a service shop checked it and said it was a vacuum leak but the code was very vague. They sprayed carb cleaner on the vacuum hoses to no avail. They reset the code and said to wait and that it wasn't anything serious.
Two weeks later, the exact same code is tripped and again the same process as above is repeated.
Two days ago, my light came on again! I haven't taken it to the service shop because I figure they will not be able to do anything to it since they couldn't find it the two previous times.

In the first instance, the pedal was a little stiff when I first drove it to my university, but then on the way to the service shop, she ran normally with maybe a slight decrease in power.

In both the second and third time, the power decrease is slight but the overall driveability is pretty normal.

The BIG thing I have noticed is a drop in my gas mileage, which as a poor college student, is a major problem!

Does anyone have any ideas or thoughts?

 

[rego]

Post the codes. Also searching the site has almost always been a big help to me.

 

[OKLAexplorer]

Yes, the site has solved issues for me in the past too! I'm about to go get the codes scanned and I will post them shortly....

 

[OKLAexplorer]

Update:

Had the ex scanned and two codes are on:

P0171 system too lean (bank 1)

P0174 system too lean (bank 2)

Any thoughts?

 

[sclausel]

Intake Gaskets

Sounds like classic Upper AND Lower Intake Manifold Gaskets ( O-rings ). These rings take a set over time and leak air into the cylinders ( after the MAF ) so you run lean. $30 fix with Ford parts, closer to $20 with cheaper brands ( but for the trouble to get to these splurge for the Fords ). Also perfect time to replace the PCV valve for $3. I did mine in December and it took around 5 hours. I work slow and meticulous. Its not that bad of a job. Do a search on here as there are a few very detailed threads devoted to this with pictures.

 

[OKLAexplorer]

I actually replaced the PCV valve with a motorcraft one today, took no time at all. I took the air filter out and cleaned it off as well as the MAF sensor. $30 for intake manifold gaskets?? that seems outrageously cheap. Where are you getting your parts from?

 

[SDR]

I picked up a set of Fel-Pro gaskets at Advanced Auto for around $17. Going to change mine out next week when it warms up a little here in OKC. When you go in, ask for the intake plenum gasket set. I'm assuming you have the 4.0L SOHC motor correct?

 

[OKLAexplorer]

Tomorrow is supposed to be super cold, I might try changing mine next weekend. I have a 4.0 OHV motor. It looks like the plenum set is $25 at Oreilly. Isn't that just uppers?

 

[Jim Jermain]

Yep that's the cost for the upper. The lower is typically around $90. The upper gaskets are pretty easy to replace. The only challenge I had is with the EGR tube. I've tried to leave the tube in place and slip the upper intake back over the tube as it is going back onto the studs. This will work but when I did it I don't think I got the o-ring on the EGR tube properly seated. I think the safer way is to take off the EGR tube out the upper manifold back on and then install the EGR tube.

Good luck.

Jim

 

[JEastonjr]

check the fuel pressure at the rail. should be 60lbs. anything less and your fuel is going to fail.

 

[JEastonjr]

check the fuel pressure at the rail. should be 60lbs. anything less and your fuel is going to fail. i had the same codes and it was the fuel pump.

 

[swetrid]

It probably needs intake gaskets, the 4.0L OHV needs the upper orings and there is a plate with gaskets on both sides above the fuel rail that goes bad.

 

[sclausel]

Which Motor

Which motor are we talking about here? The 4.0 OHV or the 4.0 SOHV ?

I've got the SOHV and both the upper and lower intake o-rings ( not head gaskets ) were $30 for both ( total ) from a Ford dealer in Wichita. They're cheap.

 

[OKLAexplorer]

I have the 4.0 OHV motor. I think everyone seems to think it is either the gaskets or the fuel pump. I'm not very experienced with the fuel system so can somebody tell me exactly how you go about checking the pressure at the fuel rail? Thanks everyone

 

[OKLAexplorer]

On my way home tonight, it was running really smoothly but it seems like it has about 1/3 less power than it should; almost sluggish? Keep in mind that I changed the pcv valve, cleaned the air filter and MAF sensor. I unhooked the battery and the codes haven't come on yet, but that was only saturday....not sure what is going on.