Intake Manifold?

[sakirfp]

I have been having issues with my 98 XLT 4.0 OHV. It has issues some days with staying runnning. Unless my foot stays on the gas it will not idiol until it is warmed up. I frist thought it was some fuel issue. I changed the Fuel Filter, and Fuel Pressure Relay. When the Check engine light came on it gave these codes DTC P0171 System Too Lean ( Bank1 ),DTC P0174 System Too Lean ( Bank2 )
I been told and read it seems that it could be the intake manifold gasket. I have 180,000 Miles on my Explorer. This has been the first serious issue that I have had with this ride.
Is there any recalls on this? If not how can I be for sure that it is intake manifold before I start tearing it apart. Reading in the Haynes Manual it does not seem hard to change the gasket. I just know it may take me teh good part of the weekend.

 

[Eneurb]

There are no recalls on the OHV for that concern.

 

[sakirfp]

Since it looks like I am going to be doing this gasket replacement myself any suggestion or tips would be great.

 

[DB_1]

I'm getting the same CEL codes on my 97 Ranger and have yet to pinpoint the problem. I've replaced a few sensors and EGR valve but to no avail. I'm gonna try and do fuel pressure test and see what I come up with, probably has nothing to do with anything but it couldn't hurt. Let us know if the gasket change helps any.

 

[Rhett]

Since it looks like I am going to be doing this gasket replacement myself any suggestion or tips would be great.

Before you go to that trouble, you really need to make sure that the intake manifold gasket is your problem. A lean code doesn't automatically mean that.

I'd start by checking all the vacuum lines for cracks or pinholes.

Next I'd check the air filter, the gasket between the air filter and MAF, and the air intake tube between the MAF and throttle body for cracks, holes, or abrasions. A lean code can sometimes indicate that you're getting unmetered air into the engine, and that air can only get in after the MAF, through a hole in a vac line, intake tube, or bad gasket at the TB or in the manifold.

Incidentally, I'd clean the MAF while I was at it, using O2-safe cleaner spray. See what that does first.

Next I'd check the IAC, and make sure it's working correctly. How-to is on this site..

Then I'd check the throttle body and throttle position sensor with a voltmeter. How-to is also on this site.

It could also be an O2 sensor problem. If you have over 80,000 miles on your truck the O2s could be worn to the point of throwing a lean CEL code.

And, if it does turn out to be the intake manifold gasket that is your problem, it is not difficult to replace the upper at all. The lower one is more difficult, but I don't think you need to go down that far, unless you're getting coolant leakage. The upper can be done in 2-3 hours, even if you've never done it before. If you've done it before, you can do it in under an hour.