93 Ford Explorer-Running like crap

[Z3CHYD]

The fuel pressure regulator vacuum line is plugged in already, thats why i was wondering what that little line was for. I went to a friends garage and got my system scanned, and the stored codes read "MAF Signal to weak" so does that mean its no good? or can it be fixed? I don't have the money for a new one

 

[manaen]

The fuel pressure regulator vacuum line is plugged in already, thats why i was wondering what that little line was for. I went to a friends garage and got my system scanned, and the stored codes read "MAF Signal to weak" so does that mean its no good? or can it be fixed? I don't have the money for a new one

well you can try cleaning the maf and the connector. Clean the MAF itself with MAF cleaner. Clean the connector with C O contact cleaner spray. Then coat the connector with Dielectric grease (tuneup grease) after it dries and reassemble it. Sometimes the connections get oxidation in there which causes a high resistance situation that changes the computers samples.

If it still does not work after that you can go to a junk yard and pick one up cheap. That same sensor is used in a few vehicles.

You still need to figure out what the deal is with that hose. Is it possible the previous owner replaced the vacuum line on the FPR?

 

[Z3CHYD]

well you can try cleaning the maf and the connector. Clean the MAF itself with MAF cleaner. Clean the connector with C O contact cleaner spray. Then coat the connector with Dielectric grease (tuneup grease) after it dries and reassemble it. Sometimes the connections get oxidation in there which causes a high resistance situation that changes the computers samples.

If it still does not work after that you can go to a junk yard and pick one up cheap. That same sensor is used in a few vehicles.

You still need to figure out what the deal is with that hose. Is it possible the previous owner replaced the vacuum line on the FPR?

Yea I cleaned the MAF recently with MAF cleaner, but i didnt clean any contacts on the connectors, guess ill try that. I'm still not sure about that little vacuum line, its still hooked up somewere on the other end, because its still sucking air, but its plugged at the moment. But I have no idea if there was some accessory it was used for or not, I'll look in the intake valley to see if theres anything that it could possibly plug into, because it all looks stock..

 

[MrShorty]

From what I can see, there are basically two possibilities I can think of for that vacuum line: 1) It is supposed to lay down in the intake valley and go to the FPR (towards the front end of the fuel rail underneath the throttle body) or 2) it reaches across the space there to the air filter box where there's a thermostatic valve that controls a valve down on the intake that is supposed to warm up the intake air when it is cold (can't remember the technical term for this part today). As my '92 doesn't have an EGR system, I don't know if it could be an EGR hose or not.

 

[manaen]

there could be one more possibility, what about the heater core bypass valve connection...

 

[Z3CHYD]

This little vacuum line has confuddled quite a few people lol. I asked a friend who is a mechanic and he said look under the intake also to see if there's some phantom vacuum hookup

 

[manaen]

Man it's tough when we cannot get our hands on the engine to fiddle. There are only so many possibilities here.

 

[Z3CHYD]

Man it's tough when we cannot get our hands on the engine to fiddle. There are only so many possibilities here.

lol i guess well have to have an Explorer Forum get-together then

 

[Z3CHYD]

Well here's a good update. I found were the vacuum line goes! It plugs into the other end of the line that plugs into the airbox. So thats solved. Also I went to the junkyard today and got a used MAF from another 93 explorer sport. I unplugged the battery, installed the junkyard MAF, waited 10 minutes, and plugged the battery back in, started it and.....success!! it runs alot better than it did, now I can drive it up a hill in 4th again. The pipe that connects to the 2nd cat was cracking, and that fell off, so I took the cherrybomb and piping after it off until i can "rig" something in the near future, but I dont care about that at the moment, I'm glad its running better. Not 100%, but its not a new car also.

 

[manaen]

great! glad to hear you made some progress.

 

[fixxxer]

One thing I didn't read in these postings is if you had replaced the fuel filter. The first few postings described the exact symptoms you will get when your fuel filter needs replacing due to crud/water in the lines.

 

[Z3CHYD]

One thing I didn't read in these postings is if you had replaced the fuel filter. The first few postings described the exact symptoms you will get when your fuel filter needs replacing due to crud/water in the lines.

yea apparently the guy before me replaced the fuel filter about 4k miles ago. I dont know if i believe him tho because he lied to me about a couple things about the explorer

 

[fixxxer]

Even if it was recently replaced, if there is crud/rust/water in the fuel tank, it will eventually make it to that new filter and plug it up. Replacement fuel filters are not expensive and knowing that it was very recently replaced will help you eliminate that as part of the problem.

 

[mjancola]

Congrats on the fix. I haven't had much time to work on mine since it's not garaged and it's been in the 20's for the last week. I have not checked the intake bolts since I can't easily get to them. I did check a few things:
1. coil resistance seems decent, around 1.2 ohm between B and 1,2,3 and 12K between posts.
2. I had a fuel filter so I changed that, which is not fun in this weather!
3. I was still suspecting the #5 cyl so I unplugged it at the plug and drove a few blocks and the problem is much worse. This tells me #5 is at least partially working.
4. I checked all the vacuum lines and even sprayed carb cleaner around looking for a vacuum leak, but nothing.
So I'm not sure where to go next. I bought a fuel pressure gauge so I'll check that next. I also drove it around more to try to get a better feel for the problem. It's really weird - the problem only occurs above 25mph, when I'm applying the gas even lightly. Could this possibly be a suspension thing? I really doubt it but I can't figure out why I don't notice the problem in 1st gear.
I'm thinking of cleaning the MAF but it sounds like a dirty MAF would affect the idle and mine idles fine.
Could it be plug wires? Next time I go to the parts store I might pick some up but again why would the idle be so smooth?
Let me know if you have other suggestions.

 

[Z3CHYD]

Congrats on the fix. I haven't had much time to work on mine since it's not garaged and it's been in the 20's for the last week. I have not checked the intake bolts since I can't easily get to them. I did check a few things:
1. coil resistance seems decent, around 1.2 ohm between B and 1,2,3 and 12K between posts.
2. I had a fuel filter so I changed that, which is not fun in this weather!
3. I was still suspecting the #5 cyl so I unplugged it at the plug and drove a few blocks and the problem is much worse. This tells me #5 is at least partially working.
4. I checked all the vacuum lines and even sprayed carb cleaner around looking for a vacuum leak, but nothing.
So I'm not sure where to go next. I bought a fuel pressure gauge so I'll check that next. I also drove it around more to try to get a better feel for the problem. It's really weird - the problem only occurs above 25mph, when I'm applying the gas even lightly. Could this possibly be a suspension thing? I really doubt it but I can't figure out why I don't notice the problem in 1st gear.
I'm thinking of cleaning the MAF but it sounds like a dirty MAF would affect the idle and mine idles fine.
Could it be plug wires? Next time I go to the parts store I might pick some up but again why would the idle be so smooth?
Let me know if you have other suggestions.

about the MAF, mine also idled basically fine, but as soon as i changed my maf to another junkyard one, it ran alot better. Still not perfect, but I'll clean the one i got from the junkyard and see if that helps it anymore

 

[mjancola]

Good news - I found the problem. My rear universal joint has play! I can't believe the symptoms tricked me into thinking it was an engine problem. This will be a lesson - bad u-joints can quiet down when the gas is not applied

 

[mjancola]

Finished up the replacement today. FYI, I highly recommend NAPA over Pep Boys standard parts. I demolished the pep boys ones when a needle fell down and I had to push them back out. (I had tried to get the Pep Boys premium ones for a few bucks more but they were out of stock.) The NAPA ones looked heavier duty and installed much smoother.

 

[Z3CHYD]

Well I think i got my problem pretty much narrowed down to the maf sensor, the one i got worked for awhile, but stopped working when i used maf cleaner on it for some reason...so I'm off to the junkyard to get a few more...good thing there's an abundance of 4.0 explorers at State Line Junkyard

 

[Z3CHYD]

Well I got three maf sensors from the jy, I swapped out to the cleanest looking one and it's still loading up under throttle, I have so someone who wants to buy it Saturday, I need this problem fixed...

 

[MrShorty]

I guess I missed where you had the codes read. What code (actual number, please) did your friend pull? Was it a KOEO, KOER, and/or CM code? And, remember that codes point to problems in circuits, of which the sensor is only part.