check engine light

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xsbronco

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I have a 97 expedition.5.4L engine. For the past year and a half the check engine light comes on and goes off. When it is on the engine runs rough. The diagnostic was a bad coil. I call BS due to the fact that the problem will fix and light goes off. I have never seen a coil fix itself. So anyways, I was wondering if there was anyone out there with ideas. Has 112k miles on it. I keep good maint. care of it. I saw a post about someones 94 bronco I think and he described similar prob. Was the throttle position sensor which is my hunch. Any help is appreciated.

 

Seabronc

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Are there any particular weather conditions associated with it like rain or high humidity? The problem with check engine lights is a ton of things can make them come on. I take it by diagnostic you meant reading the code from the computer. Have you tried reading the code when the light is actually on? I was wondering about a moisture relationship because moisture could be causing an arc trail from the coil to ground or some place else in the spark systemfrom the coil to the plugs. Once one of those gets started, they clear up and don't show up again till the moistrue conditions get get right for it. Try looking at the engine when it is dark and the light comes on. You should be able to see the arcing, usually blue in color.

Good luck,

:)>-

 
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xsbronco

xsbronco

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No weather conditions. I do however remember what started the problem. :-" I cleaned the engine with a pressure washer and didn't protect electrical too well cause the prob started after that. (NO YELLING AT ME!) :D /emoticons/[email protected] 2x" width="20" height="20" /> . Anyways, the code was read by a very well established repair shop but I can't afford to keep going back for them to charge as much as they do. It would be cheaper just to replace everything. I am pretty sure now that iI more than likely put moisture in one of the sensors and ruined it. My stereo acts up more now too. like a bad ground or short somewhere cause it picks up engine noise. Hopefully this isn't overwhelming. I think the stereo might be a prob too. I was thinking of reinstalling it just to be sure. Do you think that I should just start replacing sensors. I have already replaced O2 sensors. I spoke with my mom and she ran into a prob with her 89 f350 crewcab dually that turned out to be catalytic converter prob. [-o< [-o<

 

Seabronc

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Well, anything is possible, but I'd give a look under the hood in the dark a try. It'd be neat if you could do that while the check engine light is on. Try misting the air around the engine just squirt a little water in the air from a hand spray bottle, it can't hurt.

Good luck,

:)>-

 
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xsbronco

xsbronco

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Thanks SB, I will try that check. Right now the light is off so I'll post in the future the results.

 

4xfan78

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I have a 98 eddie 4x4 expedition, my check engine light came on and after weeks of checking stuff I found that the alt. wasnt putting out enuff power for the truck. It was about 11.7 to the battery and surpose to be at least 12.5 $200 later and no more check engine light. That was my problem, might not apply to you but something to think about just check the alt. and see what its charging at.

 
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xsbronco

xsbronco

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Thanks 4xfan78. I have another symptom along with check engine light. As of right now the engine light is off but after driving for a little while the enginge rpms drop down to 200-300 as a come to a stop. It has even died before. This problem like the others comes and goes. Do you guys think that it could be alt. connections. I will check visually for now.

 

Seabronc

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With that little bit of added info, the TPS sounds like a good candidate. Another shot in the dark but worth looking into.

:)>-

 

4xfan78

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Mine was doing that also. It also had trouble starting sometimes it would start on the first time and other times it would take up to 15 min to start the damn thing. After I replaced the alt. it all stopped. Do not know if the alt. was the problem with that but kinda strange that all of the problems went away when I replaced the alt.

 

Lump1713

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try checking the IAC Motor aka Idle Air Control motor. They are known to go on fords...take it off and clean with carburetor cleanor and put it back on.. see what happens..

 
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xsbronco

xsbronco

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replaced TPS and it changed the way it runs but didn't fix problem. Also when I did the switch I checked out mass air flow sensor and( I wish I knew more about newer veh.s) when I covered the hole with my finger it would die and when I lightly blew into it while engine was running it would also die. Where would I fing the IAC motor? thanks for the help.

 

Lump1713

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You should find the IAC Motor on the throttlebody. if not look it up in the haynes manual and it should tell ya where it is but u should find on the throttle body

 

ANFO

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I had a 97 a long time ago and when I brought it to Ford with nearly the same symptoms they finally tracked it down to corrosion in the computer connector under the dash area on the drivers side. They said they see it alot with guys who plow with the windows down (??? never plow, just what they said). They took it apart (it was like clam shell halfin/out the fire wall) cleaned with elec contact cleaner, sealed it and it ran fine as long as I owned it.)

 

Yardape

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If only you were here a year and a half ago, hopefully he has found the problem by now. LOL

 

ANFO

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If only you were here a year and a half ago, hopefully he has found the problem by now. LOL
HAHAAAHA, seriously though, you know he has just been stiing there hitting refresh the whole time waiting for my reply.

 

69bronc347

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you kow its really hard to say without looking at the vehicle or the codes, im a technician at the ford dedaler, and the coilas are quite common, nut it sounds like you gaot some water in the spark plug hole where the wire goes into the haed and it was grounding out the spark, because you left it that way and didnt fix it, it made a carbon tracer, basically is a path for spark to follow, and spark follows the path of least resistance, so if you are under high load it jumps to the head instead of through the plug, also the coils can go bad so they still fire but not correctly, they only usually do this when they are real hot, when they do this they through out a bunch of radio frequency interferance which sounds like static in the radio, i know autozones reads codes for free, but dont go replacing parts based on codes, if you could get the codes i could probably diagnose your problem.

 

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