hi all, i am new to this forum and hope you guys can help me with a problem i am having with my 1998 expedition 4.6. i am going to try to give as much info as i can. well to start it off. i bought this truck off my sister-in-law which the truck sat for over a year with little driving as it sat. battery was dead with an empty tank. so, when i bought it i installed a new battery, i drove it to the gas station,got some gas and inspected it. i had asked my sister-in-law if their was anything wrong with the truck that she new of. she said that the check engine light had come on and that they had told her it was one of her plugs lose. ok. then like a week went by and sure enough check engine light on. code p0420. Catalyst System Efficiency below Limit - Bank No 1. ok. cleared that which the truck was running good. went away on a 4 hour trip, engine running good with no problems. and no check engine light. next day at our trip. it was pouring rain down. went out for breakfast with no problem. then i came up to a pretty good flooded road. wife said.NOOOO. i said we'll be ok hon. their are other trucks going through it and we should be ok as slow as i was going and the truck sits up good. at the end of the road out of the flood, came to a stop and the truck acted as if it was going to shut off so i put it in neutral and feathered the gas and the check engine light came on and it was blinking. pulled over and put it in neutral and let it sit their but the light was on, not flashing and the engine felt like if it was running on like 6-7 cylinders. checked under the hood but it looked pretty dry under their. so i let it sit till the next day hoping it was that i just got something wet and it would dry but.NO, not my luck. on our way home it was running rough with the light on. flashed a few times so i would pull over kill it and restart and go on. stopped at a autozone and before i went in i checked the coil packs which are two of them. the #4 output of the pack was dead, no spark coming out of it at all. i took all the plugs out the passenger side with two of them having ALOT of whitish buildup. so i replaced all 4 of them and the coil pack and it took the roughness away and ran good for like 2 miles. but, roughness came back with light and again flashing off and on. i do know what it means when it flashes. stopped at another autozone and this time it was #8 missfire. looked at the plug wire and it looked like if it was not pushed down all the way. pushed it down and ran good for a little and the same,, checked again same code, #8 pushed wire down drove for a while and just drove like that the rest of the way. was tired of trying to figure out what was going on. came home and decided to replaced the drivers side plugs which didn't look as bad as the passengers side. drove it around the block twice with very,very little roughness. but today, all roughness and jerking came back with light. now the code is a p0301. i'm about to lose it since that coil pack and plugs was replace. i don't know. and it seems like sometimes it runs strong off the start and then it acts up and sometimes its rough right off the back.if i run it barely on the gas it seems ok but as soon as i give it gas it starts acting up. CAN SOMEONE PLEASE HELP ME OUT OR DIRECT ME TO WERE ELSE TO LOOK. sorry for such a long post but i try not to leave anything out.

 

If it sat that long with no gas, change the fuel filter, clear the codes then drive it and see what codes return. Check your air filter while you're at it, but that won't make much of a difference. A clogged fuel filter will restrict the flow, be ok at idle, but run sluggish under acceleration. A Motorcraft filter may run you about $15.

 

Your profile shows over 150,000 miles on the truck so, I suggest that you check all of the wires and connections for the injectors as well as running a can of "SeaFoam" with the next few tanks of fuel. A non-functioning injector will show the same code for a misfire as a bad plug /connection. I would also check all of the vacuum lines and connections for breaks or collapses, especially the one you have to hunt for at the rear of the intake as it seems to be a frequent problem. Changing the fuel filter is a good suggestion as a starting point.
Stay at it as the Expedition is a great family truck, you won't be disappointed with it once you get it right.
Welcome to the FTE.

 

thanks guys, well. on my post i forget to add that before i headed on my trip i filled up and added a can of seafoam for the trip. well. today i bought the other coil pack with no progress. i did buy a fuel filter which i will be replacing tomorrow to see what that dose. i guess next would be the plug wires.... i'm really pissed with this thing. but i do know how good it ran before these issues. on that 4 hour ride it ran like a new truck with plenty of power.and very smooth. WHAT THE HECK HAPPEN. sorry

 

Sitting for a yr, lack of maintenance and working on an OBDII vehicle without a "LIVE DATA SCANNER"... Guessing cost you $$$$ and not much in return... Philip

 

well philip, your right but some of us don't have "LIVE DATA SCANNER" money so all i have to use is a matco tools mps700 scanner. i guess its not telling 100% info so all i can do is guess. hoping i fix my problem. thanks for the help thow.

 

According to the info I just read the MPS700 has the live data stream and it seems to be a pretty good tool.

 

well, i'm new to all this data tool stuff. a friend lend it to me. i guess i'll have to get his butt to help me out a bit. i just used it for the code reading. thanks.

 

Did you change ALL the coils or just two or three ? Seems like you still have a bad cop.

 

He has coil packs not COPs.

 

yes, i have the coil packs. and i did replaced with new ones. and spark plug i was wondering if the crank position sensor could be a problem. since the problem started when i drove through the flood???? I'm thinking the sensor is somewhere on the bottom of the engine,,,? maybe connection bad or something?

 

Well, some of us feel your pain. I hate OBD2. I am not an expert but have been through some of the same symptons on my 98. Some of this sounds like it went into failsafe or limp home mode. I hope you didn't replace a bunch of this because here the system may be causing it's own malfunctions. Worse to me is the likelyhood that a dealership can't pinpoint the problem or problems either.

All my major curses like yours were related to 1. vacuum leaks at maniford or behind battery, 2. loose ecu connection through the firewall

At 175k miles never had to replace a coil or fuel filter (but I did as you just to eliminate possibilities). Runs as good as new when it's right.

Good luck.

 

yea, the dealer thing. thats what the wife wanted to do and i said, well, if you want to pay a dealer or a garage TOP dollar go right ahead. i try to fix things myself. maybe spend a little doing so but better then $150 just to look at it, then $90 plus and hour to diagnose what the problem could be. then the cost of the part which is marked 50% above, and if you know dealers and garages, they are not going to pull your car or truck in and in 15 min your car or truck is fixed. ESPECIALLY if its a woman. i'm all ol school, you keep going till its fixed. far from a quitter . some guys just don't understand that kinda thing. they are quick to put someone down for not doing what they think should be right. sorry. we all do things our own ways. and asking for some help shouldn't be a problem and we shouldn't have a problem giving help were its needed. that's why we are all here. sad that some of us think that they are better then others. not me. i don't think I'm better then no one. I'm one to do what ever i can to help someone out. if you would know me, you would know .... but anyways. back to the problem i had. well. i did change the passenger coil pack first which was shot. replaced the spark plugs, then when i got home i replaced the drivers side coil pack with no luck, then bought a fuel filter which i was going to replace today. then today decided to check the crank position sensor which seemed ok. and said to myself. lets try the spark plugs wires........... i think i found my problem,,, started her up, took her for a drive and she seems to like the new plug wires... WOW, from driving for 4 hours in a smooth running truck. to going through a flood road getting a check engine light flashing to running like if it were running on 7 cylinders to buying a coil pack fixing that problem to still running rough and jerking to replacing all the other parts and here it was the wires. not sure why. but, what i spent was $195. as i understand, coil packs go out on these trucks, new spark plugs, wires and the fuel filter wouldn't hurt. so, i hope that took care of my problem. i want to thank all of you that gave your input. weather it was good or bad. BUT, i do have a winding type noise in the engine area which might be coming from one of the pulleys, again. i think from that water. thank you all.

 

I also have a 98 Expedition that has been running rough with misfire codes and a lack of power, especially when it's wet. The misfire issue has not yet been resolved, but oddly enough I started experiencing a whining noise under the hood which I determined to be the power steering pump...my power steering reservoir was empty and there was a substantial leak which appeared to be coming from the two hoses at the bottom of the reservoir. I refilled the reservoir with PS fluid and that quieted the whine, however just yesterday while driving through the snow the truck started running rough and the CEL started flashing...as I was pulling in my driveway, I started hearing the PS whining again and found the reservoir empty. Could there be any possible correlation between the PS fluid leak and the misfire/rough running?

 

Not sure if this will be any help, but I will put it out there anyway. I did a lot of electronic tuning with my 05 saab 9-2x (subaru impreza wrx wagon the looked like a sab). I bought a "tactrix cable" for $105. then there was tuning software online for free. The cable goes from OBDII to usb. There may be software out there for these vehicles. Another option: my brother gave my a OBDII thing (technical i know). It plugs into the scanner port and thats it. Then you download an app for either android (named torque) or apple phones. Then all you do is connect to it through the bluetooth and you get real time data on your phone. It may work with a laptop too but Im not sure. It will also tell you any codes that are popping as well as what they are. I think the cable he got me ran around $50-$100. I've used to to troubleshoot codes on my vehicles with great success. Hope this helps...