98 expedition high idle

[Travistyson1]

Hey guys,
I just picked up a 98 ford expedition 4x4 with the 5.4 triton and a.m. having high idle issues. It idles about 2000 rpm. I have changed all the plugs and coils, new Maf, new IAC and it went from barely running idling high. Wondering what i can do to try and troubleshoot or solve the issue. No codes in the system. All sensors seem to be working properly according to my scan tool,
I'm wondering if the previous p owner perhaps adjusted the throttle screw since it would not stay running without a foot on the gas pedal prior to me getting it and replacing the Maf and other items that was causing the CEL to be on and rough running condition.

 

[Bedrck47]

You could look into the throttle body to see if the throttle plate fully closes Very possible the screw was adjusted as you suspect. Try turning the screw and keep a count on how many turns you make so you can put it back in case that isn't your problem

 

[Travistyson1]

Ok so i measured the idle screw and compared it to the other expy i have that came with the deal and it was not the same. Swapped the throttle bodies and idle improved. Still sounds a bit like a lawn mover but it is idling proerly now. Have to change the other 4 coils hopefully that resolves the ping sound. I let it run for a half an hour and no CEL light so back to the old way of finding things. I know some of the sound is the exhaust needs to be replaced. Its in rough shape. Any other thoughs to get it sounding better. It seems to run fine now jist loud like a lawn mower

 

[1955moose]

First off welcome to the forum. Not always will a check engine light trip. You still could have codes in the computer. Buy, borrow, or go by an auto store, they run codes for free. Exaust leaks make these SUVs run lean, which affect idle. Also get a handle on any vacuum leaks, either by using a smoke machine, or old school, by spraying down all gaskets and hoses in the intake path. Other than that you've done all the other necessary things, like tune up, sensors, electrical repairs. Keep us posted after Exaust and other items get completed. Oh yeah you might want to spell check your posts, I phones flip around what your really trying to say. We know what you mean, just makes it easier to read. Moose


Sent from my iPhone using Tapatalk

 

[Travistyson1]

I put the scanner on it and still shows no codes however I'm getting 0 volts to my Second Bank rear oxygen sensor the exhaust and rough shape in some areas the muffler itself has a hole in it. I purchase a couple of rear Bank O2 sensors and will be changing those out hopefully today if the weather holds I'm hoping to hold off on doing the exhaust until I have it running good if I can because I prefer not to get the welder out and do it myself but if I replaced all the O2 sensors have the same problem that's kind of where I'm going next I have sprayed down all the tubing to see if I have any vacuum leaks and have replace the ones I found

 

[1955moose]

Travis you need to figure why you lost your 12 volt signal. One of the other guys here have schematics for your SUV. I looked in my owners book, and didn't see a fuse labeled o2 sensor. I just have an I phone so it's tough for me to bring up items and send. Hang in there one of our other members with electrical schematics should get back to you.


Sent from my iPhone using Tapatalk

 

[1955moose]

Travis don't know if your 98 is the same as my 2000, but found in the fuse panel under in engine bay the #23 fuse 15 amp is for Hego sensor. You might not only try another fuse, but check both sides for voltage. Hope that helps.


Sent from my iPhone using Tapatalk

 

[Travistyson1]

Thanks hopefully the weather will clear soon and i can take a look. I still have to change the other 4 coils and plugs. That could be the reason for voltage i guess as well. But i will check that fuse when i get out there.

 

[1955moose]

Yeah a blown fuse would definitely do it. If you've got your owners book, or maybe download one for your year, just to be sure their the same position fuse.


Sent from my iPhone using Tapatalk

 

[Travistyson1]

Well in the process of finishing changing the last 3 coils. 2 of the 3 fell apart in my hands. The rear plug came out with the deteriorating coil. Now it appears the previous owner dropped some rubber piecev into one of the plug holes as i have to figure out how to get that out before i can get the spark plug socket in to remove the plug. In addition it appears the threads for the hardest one to get through may be stripped. Its been a rough day to day the least. But hey the oil change went smooth

 

[1955moose]

Try using a 5/16 to 3/8 hose taped onto an adapter for a shop vac. You'll have to duct tape the hose around the vacuum adapter. PVC pipe, with adapters hopefully will work. That rear thread insert is a bear to do at home. Your going to need an angle drill, shop vac, and a ton of patience. You may have to farm that part to a shop. Good luck. Keep us posted.


Sent from my iPhone using Tapatalk

 

[Travistyson1]

Ok so we fot the rubber peice out. Usong mu 7 dollar borocope camera and cell phone to see exactly where it was. Lots of time frustration and praying and we got it. As far as the thread repair there is a kid for like 79 bucks at the autoparts store that i hear that the shops around use to fix this common problem. Best part is i dont have to drill out the hole and rethread it. Considering that. But there is another tool that my mechanic neighbor said his friend at ford uses at the dealer shop to repair the threads. Somehow this does not need drilling either. Trying to decide which is best. I could always yank the heads off the other expy that came with this one for parts...but dont really want to do that at this point.

 

[1955moose]

If the other shops say he does good work, and they wouldn't use him if not, go with him. Most shops charge $200.00 to $300.00 each hole. He's a bargain.


Sent from my iPhone using Tapatalk

 

[Travistyson1]

Ok fixed the threads on the rear passenger plug hole and put everything back together and she now runs perfect. Now jave to start digging into other things. I know one of my pulleys is going out i can hear the bearing starting to sqeek a bit. And have to learn about the 4wd system the front drive shaft is disconnected. Anyone have any ideas of common 4wd issues that may point me in the correct direction. And an inexpensive lift kit. Also i need to do my link pin bushings, i figure if I'm lifting it i should not do the bushings until i lift. Is this a correct assupmtionm

 

[1955moose]

The two most common problems is the transfer case itself not engaging due to either a sensor, or a solenoid, or an issue in the case itself. Being that the previous owner disconnected the drive shaft, I'm going out on a limb and say theirs a problem in the case. As always run diagnostic codes first. Their can be a myriad of problems that caused the prior owner to remove the shaft.


Sent from my iPhone using Tapatalk

 

[sphillips]

Thanks hopefully the weather will clear soon and i can take a look. I still have to change the other 4 coils and plugs. That could be the reason for voltage i guess as well. But i will check that fuse when i get out there.

Mine only idled high at 1000rpm, but new pcv fixed it

 

[Travistyson1]

It's running great now tomorrow I'm changing the transfer case motor for the 4 wheel drive and swing if that's the issue with that. I read a lot of posts about it going bad and it is very rusted

 

[Travistyson1]

OK so I did not get around to changing the shift motor, Decided I should spend a week or so spraying rust bolts with PB blaster so I dont break any, Where this is located I wont be able to get a drill in to tap the hole if I break something. I did, however finally get the inside cleaned really good, and tried to use the 3rd row seat from the 99 EB Expo that came with it, It seems the Rear seat in the EB has different brackets than the one that is missing out of mine, I can get the rear hooks to lock in but the front ones have Wheels and they will not drop down into the hole, any suggestions/advice