runnin lean

[JflexW]

I originally posted this in the v6 forum, but thus far no response, so I figured I would try the v8 guys. Thanks in advance!
Check engine light came on a while ago. My car was being a gas pig. Read my manual, and it suggested that if my car was being a gas pig, that my light may come on. So I gave it a tune up, replaceing spark plugs, airfilter, replaced fuel filter like 6 months ago, replaced pcv valve. Cleared the codes, and it drove fine for a few days. Then the code came on again. My mechanic scanned the codes, and it was runnin lean in banks 1 and 2. However the o2 sensors seemed fine he suggested just clearing the codes, so I agreed. Check engine light came on again, exact same codes. I had never had the o2 sensors changed, and he was not 100% sure that it was the sensors, but felt that it was more then likely the case. So I took the car home and to save my self the labour, I changed the sensors. Car ran great!! Then the check engine light came on again today. I dont understand... Why would the o2 sensors indicate lean, and no others sensors malfunctioning. I have no mods, other than removal of the air silencer a few years ago. I would think that if it was the MAF or EGR that they would also throw codes. But I only seem to get lean codes from the front two O2 sensors.

Advice, please!!!

On a side note, I would like to thank Ford for making the front two O2 sensors so easilly removable " jerks". The drivers side was easy, the passenger side seemed to require alot of cursing and swearing!

 

[Daniel50]

did you scan the codes again after the 02 sensors. you might be throwing different codes now.

 

[JflexW]

Have not rescanned for new codes yet, just assumed it would be the same code. It was the same codes the last few times... I will most likely check them again next week.

 

[jrichker]

On the V8 cars, the computer sets code 41 or 91 which is when O2 sensor indicates system lean. What really is wrong is the O2 sensor has gotten so old that it no longer puts out the correct voltage and the computer thinks the system is too lean, so it adds more fuel.

The following is a Quote from Charles O. Probst, Ford fuel Injection & Electronic Engine control:
"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than 400 Millivolts. Remember lean = less voltage.

When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than 600 millivolts. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage." End Quote

 

[JflexW]

Does the founding member have an automated response or something? Obviously if he read the thread he would know that I just put two new sensors in. I already know how the sensors work, I just want ideas as to what is tripping them. No other codes had come up at this point so I would assume that it is not an EGR issue or a MAF issue othewise I would have expected those codes as well correct. Also I am wondering if unhooking the battery for a few hours while I worked on it would have cleared the codes or do our computers have memory. The light was off for a bit. Could it just be that the codes have to be cleared with a scanner. Ideas please. Not automated responses.

Thanks

 

[JflexW]

Rescanned the stang after two new o2 sensors. Now I am runnin rich in bank 2. I dont get it. First I am lean in both banks, now I am rich in bank 2. I got the codes cleared and we will see what happens. It also said that I cleared the codes improperly (unplugging the battery). Anyway if anyone could give me an idea of why it would register rich on just the one sensor this time, that would be great.

 

[jrichker]

Does the founding member have an automated response or something? Obviously if he read the thread he would know that I just put two new sensors in. I already know how the sensors work, I just want ideas as to what is tripping them. No other codes had come up at this point so I would assume that it is not an EGR issue or a MAF issue othewise I would have expected those codes as well correct. Also I am wondering if unhooking the battery for a few hours while I worked on it would have cleared the codes or do our computers have memory. The light was off for a bit. Could it just be that the codes have to be cleared with a scanner. Ideas please. Not automated responses.

Thanks

The prompt was for you to get out your analog voltmeter and go measure the voltages as the car was running. That way you can see what is happening in real time. It also gives you an answer as to how well the "new" O2 sensors are working.

Possible causes for lean mxiture are:
1.) Vacuum leaks
2.) Clogged fuel filter
3.) Clogged or dirty injectors
4.) Low voltage to hot side of the injectors
5.) Low fuel pressure - bad FPR or bad fuel pump.

Possible causes for rich mixture (one side only)
1.) leaking fuel injector
2.) ground in computer side of the injector wiring

The red wire on each injector is powered up whenever the ignition switch is in the Run position. The computer provides a ground to complete the circuit and fire the injector. The injector must have a ground to squirt fuel on command. A short to ground in the injector return wiring can cause one or more injectors to be continually open or triggered

A.) A Noid light available from Autozone, is one way to test the injector wiring. If the light stays on constantly, either the wiring has a short to ground or the computer has failed

B.) I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles An injector stuck open will release a continual stream of bubbles. Cheap if you have the stuff laying around, and works good too. The same trick works great to find leaking injectors too.​

The wiring for the injectors may have some bare spots in it causing the injector to computer control wire to ground out. This would cause the injector to remain on anytime the key was in the Run position. Remove the injector wiring connectors from the injector. Note that each injector has one red wire for power and a non red wire (wire some color other than red) for computer controlled ground. With the key off, disconnect the computer connector from the computer. Use an Ohmmeter between the non red wire and ground. You should see more than 100000 (100K) ohms resistance.

Check your V6 specific shop manual for a cylinder balance test. If there is one, run it and see if it spits out a specific cylinder. That cylinder would be suspect for a bad injector.

Since this is a 5.0 forum, the information is limited to things that specifically work on 5.0's. Anything you glean from what is posted (canned responce or not) is gravy.

 

[JflexW]

Did not mean to offend the moderator, but I have been to sites where specific words trigger an automated or canned response. I did get the message about you wanting me to use a voltmeter to check the performance of the "new' oxygen sensors. However in the beginning of my post I suggested that I was getting the codes from the original oxygen sensors, however now I got a code from the new oxygen sensors. Which made me question as to why I would do a test on brand new oxygen sensors with the check engine light coming back on. I was thinking more that I missed something. And was looking for suggestions as to what it could be other than the o2 sensors. I am not a mechanic and some of the stuff you suggest goes over my head when I leaf through the threads and I have to look it up, but hey I am learning which is why I come to this website. During the process of reading through countless posts trying to come up with Ideas, I did see the same responses over and over again which suggested to me that these were automated responses triggered by words which had been included in the question. Hence I wondered if you were a real person or what is known as a bot. Obviously you are real, so again I apologize for offending you. I also realize that this is a v8 Forum and that some stuff does not apply to me, however if you looked at the v6 Forum, the numbers have decreased dramatically for some reason. I figured I would be more likely to get a response from a form with 215 people online, rather that a forum of 7 online, most of which are young and have the same if not less knowlege that I do about cars. For the most part all cars work the same, meaning a sensor is a sensor is a sensor, and despite the fact that you have two more cylinders when it comes to this stuff other than different coding it is basically the same problems. And I would not say just because this is a v8 forum that anything I come across and learn is gravy. That just comes accross all wrong to the reader, like it is a privelage for me to be reading the v8 forum. Trust me I enjoy reading and learning about cars as much as the next guy but it is not a privelage. Cause even if I dont drive a 5.0, I still look stuff up and make and suggest purchases from your sponsors. So making the v8 forum come accross as arrogant is probably not a good Idea to attract new members and keep old ones. And more members = more sponsors.

Anyway enough yapping on my part, I got a hot date so I am outta here!

p.s. hope ya dont ban me cause ya did not ike what I had to say

 

[HISSIN50]

Jrichker is not a moderator that I know of - he is just perhaps the wisest person I have come across when it comes to understanding all facets of working on cars and other mechanical items.

He is not getting paid to help you, nor does he get anything for doing so. I try to not have much of an attitude when I need help and start threads, even if people that I know have less knowledge than I do decide to try and help me and post. I thank them for taking the time to try and help.

The info he provided would do you well in getting you on track in finding the solution. There is only so much we can do, especially given that you did not even provide vehicle year or info that I saw (I presume you have an OBD-II v6?).

No one is looking for drama, but if anyone on here deserves respect, it is Jrichker. He has put together long, very articulate posts addressing many of the common issues which crop up time and time again. These posts allow him to relay that info to each new thread-starter (no one would have the patience to type out such detailed posts by hand every time). The troubleshooting flow-charts in my manual dont change every time I look in the book because the info is informative fact, just like his posts.

Good luck with finding the source of your car's issues.