Hello,

I am fairly new to this forum and would appreciate any input on my problem. I have a 98 Explorer Sport, 4L SOHC, 4WD with 98k miles. Recently, it's been running rough -- it seems to "hiccup" when it's idling. The problem isn't consistent, sometimes it seems to run fine. I have also experienced surging while driving (around 45 mph) but that hasn't happened often. Before these problems began, I noticed it was idling rough at start-up -- it sounded as though it was going to stall, then something would kick in (it sounded as though I had stepped on the accelerator even though I didn't do anything). It would cycle like this at least 3 or 4 times.

I took it to the dealership and they told me they think I have a cracked spark plug. They said one of my cylinders is dropping out, but they can't tell me which one.
The plugs (& wires) were new a year ago. Then I bought myself a Haynes manual and discovered this site. I'm not convinced it is a spark plug problem after everything I've read on the forum. I had AutoZone check the OBD codes and the only thing that came up was P0171 (system adaptive fuel lean - bank 1). I cleaned the MAF sensor today, but it didn't look dirty to start with.
I spoke to a guy today at AutoZone and he seemed pretty sure my problem was with one of the O2 sensors (partly because I'm only getting the code on one bank). However, one of the postings I read on the forum said if an O2 sensor is bad, my Check Engine Light would be on. I am NOT getting the CEL.

My first question is do you think the O2 sensor is really the problem? If so, how can I find out for sure which sensor is bad -- would it be the front sensor on the passenger side?
If so, then my next question is WHERE exactly do I find this sensor (I can't really tell from the Haynes manual)?
Should I go ahead and pull the plugs out to look for cracks?

Any and all advice is greatly appreciated!
Thanks,
Sandy

 

Bank one is the passenger side on the V6,side where plug number one is. An O2 code would have additionaly said sensor 1 or 2. One being engine side of the cat and two after the cat. I wouldn't discount the plugs. I have had these go bad in ess than 4K. Look at the insulator section under the boot. Fine cracks can develop there. I have a tiny antifreeze leak that I have been ignoring that causes me to replace my #4 plug often. If your plugs check out good I would be inclined to suspect a lower intake manifold leak. As far as the O2 sensor, you has your fun and you take your chances. Keep the old one, you could use it some day.

 

Thank you for the reply.
I pulled the #1, 2 & 3 plugs today and as far as I could tell, they all looked OK. I figured it wasn't going to be a plug... that would be way too easy.

So, I guess I'm looking at tackling the lower intake manifold gaskets that I've been reading about on this forum... yippee.
What really irritates me about this whole thing is the fact that I have owned my truck since 1998 and never received any notification (ONP) about this problem from Ford. I didn't get anything about the cam tensioner on the timing chain either. I did, however, get a notice about the chain guides.

While I was under the truck this afternoon, I did locate what I think are the two front oxygen sensors. Does this thing actually have TWO catalytic converters?? It sure looked like it.

From everything I've read here, I believe the problem I was having at start-up is related to the intake manifold leak -- however, I haven't experienced that lately. Does it seem odd that it doesn't happen more frequently? Also, I was (am) not getting the "check engine" light. Any chance it could be something else?

Do you think the "hiccup" while idling (when warm) could also be related to the intake manifold or might that be caused by something else? Again, it doesn't happen all the time.

Any and all guidance is greatly appreciated.
Thanks!
Sandy

 

New to this forum but see that everyone is very knowledgable and helpful as well.

I have a 1997 Mountaineer with 53k miles on it and I saw a nosedive of 3-4 mpg's recently and had that happen on my 89 Taurus at the same mileage and once I replaced the O2 sensor, it was like new again.

Problem now is that I installed the 2 sensors on the left,bank two side, which now results in a short period of fast idling when cold, smoother running and more pep, but I am unable to reach the connectors for the right side sensors. They are mounted on a bracket bolted to the right side of the tranny but they are up on the top of the tranny and I cannot get my hands up there to disconnect the connectors. I have taken off the heat shield on the tranny and still cant get to them.
Is the only solution to drop the tranny and transfer case down a bit? Anyone have the same experience or a solution? I think if I can get these two changed out, my mileage may return to better numbers.

Steve in Palm Coast,Fl.

 

Have you tried accessing through the fender well? You'll have to remove the inner skirt, but it makes life much easier in the long run. I removed the skirt and popped the mated connectors off of the barb connector. I was then able to grasp both halves and depress the locking mechanism.