98 Explorer Problems
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98 Explorer Problems
Hi, i'm new to this great site. I have a couple of problems with my Explorer 98 77,000 SOHC. First and foremost these problems might be related but i need help. Early in the morning when i'm taking my kid to school, i start up the Explorer and the engine idles very rough, sometimes it will just cut out. But if i step on the gas and warm it up it runs fine. After that all day it will run fine. It's just in the mornings. That's my first problem. Second, the check engine light went on and i cleared it after writing down the codes-P0171 Bank 1 Sensor 2 P0174 Bank 2 Sensor 2 A couple of days went by and the light went back on. Scanned it again same codes. So far i've just cleaned the air filter and i've looked for vacuum leaks, but have found none. I really need some help.
Ps. almost forgot i purchased PCV valve something like 1-2 years ago and can't find where it go's. It's been in my glove box all this time in original packaging. Need help locating it. Thanks
Ps. almost forgot i purchased PCV valve something like 1-2 years ago and can't find where it go's. It's been in my glove box all this time in original packaging. Need help locating it. Thanks
Freshman User
Joined: Dec 2003
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I have the EXACT same problem with my truck, also the 98 4.0 SOHC. today i just replaced the Idle Air Control valve, but I won't really know if this fixed the problem until my truck gets completely cold again--probably tomorrow morning. Every time I talked to the Ford guys, they mentioned the IAC, then I checked it and found a short. hope that was it. i'll let you know tomorrow. if you find something else, post it here. we have the same issue, i even had the same trouble codes...
Senior User
Joined: Dec 2003
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From: Union Grove, Wisconsin
Check the IAC first. Many writeup's on this site showing how to do it. If that is ok, do a search on TSB M0012. This had to do with the lower intake o-rings. You might also want to check your MAF sensor. Mine does the same thing. IAC is ok. Injected propane into intake to verify bad o-rings but didn't seem to help. Removed my MAF and now idles pretty good with it removed. I will be installing it tonight after cleaning. Do a search on these items and you'll probably find your problem.
Elder User
Joined: Aug 2003
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From: Tampa
Originally posted by jesrazo98EXPLORER
I've done the following so far. Clean air filter and IAC. I'm going to clean the MAF next. Still need to know where my PCV Valve is?
Have not checked the O-rings.
I've done the following so far. Clean air filter and IAC. I'm going to clean the MAF next. Still need to know where my PCV Valve is?
Have not checked the O-rings.
Freshman User
Joined: Mar 2003
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From: WI
I had the same problem with my 98 4.0SOHC at cold start and the problem was solved by redoing the intake seals. It would run fine after warm up but continually got worse at cold start up as time went on. I had a dealer do this as it is a time involved job.
Big Wood
Big Wood
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I also have the EXACT same symptoms on a '99 Explorer 4.0L SOHC. I also periodically get the same 171/174 codes (System Lean, Bank 1 / 2). My symptoms started showing up last winter after taking the truck in for a coolant flush when the engine was still cold. Since then, I have checked the vacuum lines for leaks (no leaks), replaced the IAC (No Effect) and all four 02 sensors...No effect on the cold start troubles..still waiting to see if that will affect the Lean Condition codes. By the way, the cold startup problem went away for the warm months, but is back in full force this winter.
BigWoods, do you have any other info on the intake seals? Was your vehicle throwing the same codes also? Much appreciated!
BigWoods, do you have any other info on the intake seals? Was your vehicle throwing the same codes also? Much appreciated!
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Update
I have done some more things to try and fix my problem.
I cleaned out the MAF i cleaned and oiled my Air filter, I changed the PCV Valve and i cleaned the IAC Valve. So far i have not picked up the codes yet. THANK GOD I still have cold start problems in the cold mornings, but i live in Southern California so i hope the warm weather comes soon. Please update with any new ways of fixing this. Thanks
I cleaned out the MAF i cleaned and oiled my Air filter, I changed the PCV Valve and i cleaned the IAC Valve. So far i have not picked up the codes yet. THANK GOD I still have cold start problems in the cold mornings, but i live in Southern California so i hope the warm weather comes soon. Please update with any new ways of fixing this. Thanks
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Fleet Mechanic
Joined: Oct 2003
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From: CentralEastern Utah
My 2000 expolrer is also doing the same thingas above. Rough idle on cold starts, Bank1/2 system lean. I Cleaned the IAC and did the electrical checks on it as listed in the sticky. Checked for vacum leaks, nothing. Changed the MAF nothing. What I did find though is that if I unplug the MAF while its running rough that the engine smooths right out. Anybody elses do this?? What does this mean??
Freshman User
Joined: Mar 2003
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From: WI
Krankem I checked the invoice when they did the intake gaskets and according to the invoice they checked for codes and didn't find any. it says 88591 checked EEC all pass checked oasis and called hotline checked PIDS all ok possible intake gaskets.
Dealer called it bad rolling idle at cold start up ok after warmed up.
total for the job was 298.13 Big Wood
Dealer called it bad rolling idle at cold start up ok after warmed up.
total for the job was 298.13 Big Wood
New User
Joined: Jan 2004
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98 ford exporer XLT
I'm having the exact promblem with my 98 Ford explorer 4.0 SOHC engine. I'm getting Banks 1 and 2, Sensors 1 and 2 too lean (codes PO171/PO174). It happens on cold startup. After engine warms up the rough ideal goes away. O2 sensors on both banks appear to be malfunctioning during real time diagnostic scans, however, engine runs well dispite lean conditions. It has me puzzled.
Fleet Mechanic
Joined: Oct 2003
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From: CentralEastern Utah
I have checked numeruos time for a vacum leak with starting fluid. Can't seem to find anything though. I also have a bad o2 sensor but can't see how that makes a difference on the cold start. Has anybody unplugged their MAF sensor while your engine is running rough? If I do it to mine the engine will smooth out.