The amber "check engine" light on my 98 F-150 has been on intermintently for the last two weeks. I thought I might have got a bad tank of gas, but I've filled the tank twice with premium fuel and added "heet" each time. The kicker is that the engine is running like a top.

Anybody have any ideas about what's going on?

 

A lot of times it is just something emissions related. The truck may run fine with the light on but not get as good gas milage. It's worth getting it checked out by the dealer though.

-Jon

 

Hi Hab...

How many miles on your truck? Always important to post that.

Is your gas cap ok...seals tight when put on?

Something is going on..thru pcm...it may/maynot go away...of course if ck. light full time...then a trb. code mayhave been thrown...which youll have to scan and find out what it is....

Yeah, kinda wierd how it works..intermit. ck. light, but runs ok.

Good luck....OT

 

edit

 

Thanks for the quick response, guys. I have 62,000 miles on the odometer. (4x4 supercab with the 302)

I did check the gas cap, and it appears to be sealing fine. Shortly after the first fill-up the light went out, but then lit up again at a half tank. After the next fill-up, the light went out after a quarter tank, but came back on after only about 50 miles. And, it's been on steadily for the the last three days.

I just hope it's not the catalytic converter ($$$), but as I mentioned, it runs fine and there's no funky smell coming from the exhaust.

 

Pardon my ignorance, Max, but how do I scan for codes?
I assumed that would require a diagnostic tool. If so, what is it? and how much does it cost?

 

edit

 

1997 f-150 xlt 4.6l engine. Started to get rough engine with check engine light. Dealership diagnostics said bad coil on #2, paid $50, drove 5 mi down the road got rough again. Had to drive awhile until I could return also got intermittent flashing and steady check engine light with the roughest performance climbing a grade just before downshift in automatic. 38,000 miles.
The second trip to the dealership diagnostics said it is definitely a code for plugs and wires. They want to charge $500 to replace all wires and plugs. After they said they did not have the parts I went home for the day. The next day when they still did not know when they would get the parts, I went in and drove it out. Stopped at NAPA to get $100 plug wire set and $1.60 platinum plugs.
I have changed plugs and wires on other older cars, but not on a late model engines.
Can anyone give me any pointers and or recommendations on replacing plugs and wires. The dealership supervisor told me that one plug on the right hand side is tough to get to but possible with a 6" extension and a universal joint.

ruffrunner

 

Max,

I guess you have a hard time reading between the lines, because you are apparently too busy feeling mechanically superior to anyone looking for a little guidance, to give any advice that isn't sarcastic or belittling. Yeah, by the way, you're right; my engine isn't a "302," it's the 4.6 liter V8. I understand that my truck is suffering from either a fuel or emission system problem, and I was just checking to see if anyone had a similar experience and could offer any friendly insight.

Just so you know, the "check engine" light went out this afternoon. Will your $160.00 budget scanner diagnose the problem now?

If it comes back on, I'll buy Sun's $25 Ford code scanner. In the meantime, I think you know what you can do you with your specialized vacuum tester and exhaust pressure tester.

 

My advise to you, habanero, is to first change your name from something spicy to something more appropriate. Perhaps something abrasive like "Brillo Pad" or "Scratch"

max mitchell, has been around for a while and his advise is proper. You should be humble and listen because it's glaringly evident that he knows more about your truck than you do.

There a lot of possibilities for your MIL to illuminate and your best bet is to buy the AutoXay scanner for around $225.00. It's a very useful and thorough scanner and when you consider that a dealer charges $100.00 to retrieve codes and farts on your seat at the same time, it pays for itself and works on any OBD II computer.



The $25.00 Sunpro scanner is for EEC-IV computers and won't even plug into your diagnostic port. Your F-150 has the EEC-V and needs a more complicated scanner.

The trouble code is stored in the computer for 40 warm-up cycles even after the problem is fixed so it should still be in there. You are better of retreiving it and fixing the problem rather than resetting your computers memory or changing parts.

Without the scanner, we can only throw out ideas.

 

edit

 

Habanaro- Those cheap code readers will read the code and tell you what circuit it's from, but without a shop manual it is still tough to diagnose the problem. The $3,000 scanner the dealer has will tell the tech current codes, pending codes, any codes within the last 40 starts, it will also tell him the voltages through all the sensors, how fast you were driving, air/fuel mixtures etc. Even as an experianced tech i find it hard to trace problems with just the code readers. Most dealers will only charge 1/2 hour to diagnose the problem. Chances are it is something easy like a tank bypass vsv or something. Maybe you could have them read the code for you, print the freeze frame data, then get the part from a parts store and install it yourself?

-Jon