Hi guys, I have a 97 Explorer 4x4 OHC, 73,000 Miles, that has had an idle problem for a while that I just can't get rid of. Actually I think it might have been several faults contributing to one gigantic problem.
I'm in the UK (so no support from Ford even though they sold this car here) and I've been trying to fix this so I can submit the car for it's annual roadworthiness exam. If it can't idle they can't do the test so it's off the road till I can fix it otherwise I get big tickets and demerit points on my license if I'm caught driving it:
Anyway, the problem seemed to be the classic IAC problem; idle fluctuating up to 2500 RPMs and down to a stall, IAC howl and also a fairly obvious intake vacuum leak.
So far I've done a full major service (fluids & filters all around except the fuel filter) plus plugs, plug leads, IAC valve and upper & lower intake gaskets.
I've got rid of the vacuum leak (at least I can't hear it any more) and the IAC howl is also gone but it still won't idle. Before replacing all the components I got a bunch of codes set but they've all cleared except for P0171 and P0174 which keep recurring whenever I reset the system. The CEL does not come on.
Could this be a MAF problem (the car has the original airbox set-up. AFAIK it hasn't had a K&N or similar filter fitted in the past but I couldn't swear to it)?
If so, how can I test it? What can I expect to happen if I just unplug the MAF when the engine is running?
And what about the fuel filter? I'm not sure it's the filter because the engine has plenty power and runs well at any speed above idle. I've heard that you shouldn't change this unless you absolutely have to on this car, normally it would be the first thing I'd do in a case like this.
Any and all help appreciated.

 

P0171 System Too Lean (Bank 1)
P0174 System Too Lean (Bank 2)
Could be the MAF, misinterpreting airflow on the low side then cutting the fuel back. I think if you disconnect the MAF the engine will run based on data tables and not "real-time" data. I hadn't heard about not changing the fuel filter before, it's a routine maintenance item, it's cheap so I'd replace it if you can't remember the last time you did.BTW I have a 97 XLT 4.0 189K miles.

 

Thanks Vic.
I was in Atlanta Ga in April just when the idling started to become intermittent with the truck (had it about 2 months at that point and it ran well although I knew I had a vacuum leak problem). I had the good sense to buy a decent code scanner at Advance Auto Parts (because nobody does a free code scan hereabouts, cost is usually $50) and a bunch of service parts. Needless to say it has paid for itself over and again!
Anyway, I pulled the MAF wire today and the engine ran!
"Idle" was around 3,000 RPMs though so it's not usable like this and I'll have to clean & test or find a MAF sensor someplace to get it through it's annual roadworthiness test.
Within 5 seconds of plugging the MAF back in the engine died again.
Now all I have to do is find someplace open when my g/f returns with the other car to buy a set of "security" torx drivers, my set is the older kind that doesn't have the hollow shaft.
I'm impressed with your mileage, I'll be happy if I can get 2/3rds of that from mine and still be reliable.

 

You know I'm in England, right. I mean I didn't have the truck in Atlanta with me at the time!

 

Had me going there, I know some people travel heavy but....When I replace the MAF it came attached to the aluminum housing so all I needed was a screwdriver to remove the clamps. How much is gas over there?

 

I was able to find the security torx bit at a mom and pop hardware store. Maybe just cleaning it with some throttle body cleaner would help....It did for me. I saturated an old tooth brush with tb cleaner, and VERY carefully put the wires into the bristles of the brush and gently scraped the wires with the tooth brush.

 

allan1010,

Dont be surprised with the milage, I have 2 in Canada, and we do the fire /dive Rescue thing with them, 92 (338K) 97 (300K) so they get a real workout, both have the bullet proof 4L OHV engine, only soft spot is the transmissions.
yes the MAF, presents the problem you mentioned, have cleaned mine numerous times.