My check engine light came on in my 96 F150. Take it to the garage,Guy say it was a bogus code. Resets my computer,next day light comes on again.He check it again,says its burning rich on 1 sensor,lean on the other sensor.I buy all three sensors and replace them all(as I was told to do) Next day the light comes on again, I call the guy and ask WTF is going on.He says it is just a hit and miss situation. I am a contractor I don't go to peoples homes and tear out their main panel box when it may only be a bad bulb. Is this guy jerking me around and there is no other way but hit and miss? Has somebody had this same problem? It spits and sputters Please help me
I'm going to work on my '70 least there is no F---ing computer

 

Hehehe.

This is exactly the situation I addressed in another thread.

And what happened to you is EXACTLY why you don't reach for the code scanner first. (So much for the tool box full of hammers, eh AjRagno????)

Please read my responses (and disregard the harsh tone) and your question should be answered. If not, please post any additional questions you have and I'll try to help. It's tough to diagnose over the internet, but some problems have a 'signature' series of events that happen (regardless of what 'mechanics' may have you believe).

I've been through this exact same thing more times than I can count and it's always the same. Some techno-nerd just won't believe that diagnosis can happen if it isn't through the computer.

---WrongdayJ

 

I dropped it off at the garage this morning,waiting to hear what they have to say. After the 3 o2 sensors what can be next?
Could it be as simple as a vaccum line? I just bought this to have as a work truck ( only has 39 K on her ) I just got my
LEMON LAW check for my 2001 Sport Trac. I may be switching truck brands soon.
Any advice would be welcome
The first code reading said false code
Then it said 1 sensor was burning rich
other sensor burning lean
Replaced all 3 just to be safe ( $200 )
Next morning after about 30 miles on the highway
it started to spit and sputter and lo and behold the light is back on!! 39 K and 3 new o2 sensors what could be mext
1996 4.9 6 cyl

 

I have an '01 and have had to have the sensor that checks the back pressure (BPE) replaced 2X in the last 10 months. Just another possible culprit.

 

You're dealing with an incompetent mechanic. He's not taking the time to understand what is going on with your truck, but rather just throwing parts at the perceived problem hoping to get lucky.

This is not a hit and miss situation. This mechanic is taking advantage of you and it's not only unethical, it's also criminal. He's put you in a situation were you want your truck fixed, but you're also at his mercy because of the money you've spent.

You've already invested your time and money with him so it would be a waste of both to just walk away and go someplace else. What I'd suggest is that you take your truck back and tell him he has "1" last chance to fix it proper before you contact the Attorney General's office. If he's unwilling to work with you, also send a letter to the Better Business Bureau and the City hall where his shop is located.

Threats put you in a situation were you may feel guilty because this is a human being you're dealing with and wouldn't like it if someone threatened you. The reality is that if he really isn't fixing the problem, then he has no business working on cars. If it comes to this, the odds are that he'll call you and offer to return the labor fees charged and perhaps some cost of the parts. In return, you withdraw your complaint with the BBB and he keeps his membership. I've scene this happen many times.



Running rich or running lean is not indicative of a bad sensor. If the sensor's voltage does not vary or varies erratically, that's suggestive of a bad sensor. Something upstream from the O2 sensors is acting improperly and telling them to adjust for rich or lean conditions. At just 39,000 miles, it is probably an intake leak or a loose connection on an upstream sensor. An air intake sensor may also be dirty, allowing more air to enter the engine than it is measuring.

For the most part, engines are put together in a logical, sensible manor. If you look at the engine and notice all of the sensors, wires, tubing and pipes, you will notice how all of the parts interact and form a system. The sytem is simply designed to turn a controlled explosion of fuel and air into usable power as efficiently as possible. If you're mechanic can't fix it, you can. The 4.9L is a simple engine. Get out your multi-meter, some common sense, and spent some time studying how the engine works with all these sensors and hoses. The mechanic is supposed to know, so he doesn't have the luxury you do of taking your time.

hmmm....I wonder if we've found a mechanic that doesn't understand the EEC-IV computer controls???

WrongdayJ,

You have the reading comprehension and temper of a 6 year old. You can go one and on about my comments, but everyone with common sense is reading and understanding what I'm saying. You're the only one who thinks I said replace what the scanner said was bad. You're very entertaining for everyone here. I'd call you a moron, but I don't need to


P.S. Don't believe, J when he says that's not a box of hammers in his hand.

 

My 2 cents. I agree with AjRagno. Sounds like a vacuum leak or even a dirty injector. I might even think a bad ECT sensor if you were having hot start problems.

 

First I always get the code from the BEFORE I clear it.
That is how I do things, I'd like to know what caused the first CEL, and if it comes back, it would be nice to know if the first and second light were caused by the same code, or different codes ( which would aide in weeding out were the problem is at ).

Not sure if the mechanic knows this, but the code does not tell you what to replace, it only says where the problem was found.
Trouble shooting 101 tells you to look backwards from the problem area, to the point of where you know the goes into was good ( take in half, check, in half check, etc ) Nothing is an island onto itself, and code scanners were not meant to make mechanics out of lay people. This is a misconception of code scanners, it only tells you where things are reported bad at from there back is always suspect. This includes non computer items as well ( vac hose as an example ). I do not know if this is common sense to you or not, I was pointing out what your mechanic might be usng it for. If you understand this...please disregard the previous paragraph. AjRagno has detailed this topic as well.

If I got a pain in my left arm, and smelled toast, I would not take a nap, and see if it came back...I'd go to a doctor. I don't relish the idea of steering a wheelchair with a straw for another 35 years.

On another note, I do not recall if these symptoms are associated with the EGR getting the scaling built up on it. I have a 5.4 and this is not common on the 5.4 ( yet ? ), so I do not know how it reacts.
I think the code is a 401 or the likes, check the war and peace length posting list from jefflaws to fnd out if this is applicable to you. I could be way off in suggesting this, but my feeble memory is telling me the spits and sputters symptom might be from that ? Again check this over, using jefflaws posts VERY CAREFULLY ( I can't stress this enough, I do not know for sure, I would have to say 50% sure, and that sucks ). I also cannot recall if that is a 4.2 or 4.6 problem. Take this paragraph with a HUGE gran of salt, it could be way off base. Again jefflaws post list, I cannot make a big enough deal out of the research that needs to happen with this, as I stated I am not sure...just a thought.

What AjRagno said about working the BBB and states atty into this is a good suggestion. This usually gets peoples attention, when they know they are not going to push you around waiting for them to actually fix it. In any spare time start looking for a new mechanic

 

Hmm.

You both make sound arguments, and I can't say that I totally disagree with what you are saying. All crudity aside, I am a big advocate of checking for obvious hardware problems (like vacuum lines, wiring harness connectors, PCV valves that have popped out of their bosses, etc.) before jumping into the computer side of it, mainly because 90% of all code related problems I've had were linked to such things as loose connectors and cracked vacuum lines and the like, and not faulty sensors, or ECU problems. Most of the time even seasoned mechanics can be lead in circles chasing what the computer is telling them. So to that end I would say that in the event that your light comes on and you are experiencing serious driveability problems, then of course, check the code then proceed with the diagnostics. But a light without a noticeable change in driveability would cue me to look at obvious hardware (particulary emissions system related components) first before I go into the code book.

Or the toolbox full of hammers. . . . . .


---J

 

I've never had my light come on under false pretense. Only time is has come on was when I forgot to plug in my maf connector.

My truck is a brick wall.

 

Some dumb a$$ putting the gas cap on did not pay attention and tighten it. After all these years you'd think I could do something this simple

The code desription inpart read :
Problem between the steering wheel and the drivers seat. Replace driver, tighten gas cap, reset CEL, check again.

Guess what the problem is gone now, the telcom equiv. problem resoultion of [ Replace end user, tested ok]
SBC calls it no problem found..one jack off in testing circuit

 

I have a 1998 F-150, 4.2 v-6, codes are P1537 and P1538. Translations are: Intake Manifold Runner Control stuck open,bank 1 and bank 2. Do you think this is a sensor problem? If so, where are the sensors locarted. Any suggestions greatly appreciated.

 

Bobsince58,

This should lead you in the right direction.

The vacuum motors are located on the back of the lower intake manifold. One on each side. You can see the 2 blue wires running into one of the motors.

 

Actually if you refer to that pic posted, those blue lines you see are the vaccuum lines. The electrical connection is behind these and down lower and not visible in any possible way except with the manifold off or the engine out. You can feel the wire connections to make sure they are tight. And you can physically move the rods back and forth and verify they are open and closing.

They route to one other sensor (EGR I think I remember) and then back to the main manifold I refered to. Check it out and I wouldn't be a bit surprised if they are in need of help.