I had a check engine light come up, Autozone read the code for me, it said Right bank to rich. I changed all the spark plugs thinking one could be fouled, and then checked the air filter, it was filthy! After fitting a new air filter and resetting the check engine light I have no more problems. I count myself lucky it was this simple!

 

I had Auto zone read my codes yesturday on my 98 explorer sport due to rough idling in the cold morning the told me it time for a tune up, iac sensor which i just repalced this fall,pcv valve , air filter , they told me to do that & they would reset the computer for me!

 

Had my oil changed at a quicky change place. Left and 2 minutes down the road light came on. Drove directly back, and we found when they checked the air filter he had pulled the hose of the valve body. Put hose back on and reset light. Light came back on about a week later. Had autozone check codes, showed rich banks 1 & 2. They suggested replacing MAF sensor. Any one else have problems. 2001 sport trac

 

Sounds to me like Auto Zone is out to sell a lot of parts with their free check

 

i have a 95,4.0- xlt. i had a cel come on.checkerauto pulled the code which said (bad air flow,egr.so i replaced the egr,light still came on. replaced the dpfe sensor, yes- no more cel. so much for more efficient electronic diagnostics.some way some how the auto producers keep making them more costly,but not as efficient,and worth the money as they,ld like you to believe,just my 2 cents

 

After installing a K&N air filter, I now have a CEL code for lean banks. Should I assume that the computer didn't recalibrate for the new higher airflow? Is there a way to get this to work? I'm about to install 1.7 ratio roller rockers for a bit extra lift off the cam and know it will only get leaner if the computer cant keep up...

thanks and peace,
da Celt

 

You guys need to remember who you are dealing with at the parts stores. If they were real mechanics do you think they'd be working at a parts store? The codes that are pulled are outputs from the EEC. You didn't mention what year but the data is only as good as the technology and resultant software written at the time. Don't put off your laziness or lack of troubleshooting ability on a poor sales guy at Autozone or the "dumb" computer in the car.

Many companies make PCM testors. Mine is from Autoxray and works great at telling me what codes are being generated. My EEC-IV can even display 18 outputs at once realtime when the vehicle is running. This is great for troubleshooting. Again, these are from the ECC and a software program. Nothing will ever beat a human brain for digesting and analyzing all the data and all the information going on with an engine. This is where you, or a good "real" mechanic come in to play.

Case in point. I was getting code 176, left bank lean. What would cause just the left bank to go lean? Car has 2 O2 sensors, one right, one left exhaust tubes. MAF sensor affects both sides. Maybe plugs or wires. EGR is on left side - maybe it's sendin too much exhaust gas back into the intake manifold - but that would affect right and left cylinders.

Checked plugs and all three on left are black. It's actually running rich, not lean. Right side plugs were perfect. So why? What is chance that all three wires on the same side have intermittent miss causing it to run rich? Not that good I think. Why then too is the PCM giving a lean code whne it's obviously not lean?

So then again, what are the devices that control right and left side independent? Only one - O2 sensors. So I checked the left sensor and it too was black with carbon soot, just like the plugs. But on the outside of the sensor body - I didn't even remove it. How on earth could this be blackened on the outside? A leak past the threds? No, threads are good.

Well I went ahead and replaced the left O2 sensor and all plugs and wires since I had never changed the wires and might as well after 165K miles. Codes cleared and never came back.

I guess my moral here is that even though you get a code, it might not be the right code and you can't rely on a parts guy to give you the right answer eveytime. We all need to be responsible for our own troubleshooting if we chose to work on our vehicles.

And in case you are wondering about my left sensor failure. It had an internal leak and the exhaust pressure pushed exhaust fumes through the sensor body and deposited them on the outside of the body due to the end cap design - just how it was manufactured. And since an O2 sensor works by comparing the outside air to the inside exhaust and through an electro-chemical process, generates a voltage (just like a thermocouple) sent to the PCM, it was actually comparing exhaust to exhaust fumes. Since the outside reference, air, is always fixed at ~20% O2, this reference was now exhaust fumes containing much less than 20% O2. So the voltage being generated was either high or low, which ever way is "lean". The PCM thought " exhaust O2 = outside O2 therfore it must be lean - send code 176". It's a fixed reference with no intelligence to think "hey, maybe my reference is wrong."

And in the mean time let's just richen up the 3 left cylinders so we don't burn up a piston - ahh, black plugs.

Now do you really think and Autozone guy is going to know this stuff?

 

Update on my problem, ended up have a leak in one of the vacume hoses. Also the 4x4 motor went out at the same time. 40,000 miles and the truck is falling apart. Last Ford I will ever buy.

 

Many write ups on 4x4 t-case motor at this website. I fixed mine in about 2 hours. There is also a relay reset switch in the back left panel, near the tire jack. Messing with this sometimes fixes the problem.

http://draco.acs.uci.edu/explorer/

 

I fixed my problems all in one easy solution. Traded for a Dodge Durango! Good luck to the rest of you guys!

 

I got a Durango a couple years ago but kept the Explorer so I still get to have all this fun. Only problem is the Durango is my wife's car.......