2005 Expedition, 66k mi. Wife thought she got watered gas a month ago when engine began running VERY rough immediately after filling at a mountain station west of Denver. Went directly to dealer who suggested adding fuel dryer, which she did. Seemed to help, and improvesd quite a bit with new tank of fuel, but problem persists and neither dryer (nor Techron) helps now. Several codes get set - most often P2198 (02 sens 1 bank 2 Stuck Rich) and P0307 (Misfire #7 cyl) but also P0430 (Cat eff below threshold), along with P0300, P0306, P0175. Went back to dealer who said it was NOT a cat converter issue, and tried to sell her a fuel level sensor??? She declined. Now running very rough again, and noticeable smell of too rich. Hard to restart after driving to parts store and buying their best OBDII scanner, which fist yielded all the codes above, and P0307 and P2198. It logged data, but I have no way of knowing what the values should be. O2 B1 S1 read 0.080v and STFT(?) B1 S1 was -7.8.
Is it safe to conclude I need to replace the B2 S1 O2 sensor? If so, where is that thing - the Checker store checked all the other stores and everyone in the entire Denver metro is out of the repair manual for a 2005 Expedition.

 

Engine is 5.4 3V.

 

What a mess !!!

1st, what scanner & model did you get ? I assume the Actron. That is what most chain auto stores are selling.

2nd, instead of the putting any more "fuel dryer", (gas line antifreeze) into the tank, try to find a good gas aditive to clean through the system. I suggest 2 bottles of Lucas injector cleaner or equivalent. Chevron makes a good one as well.

On my F150 5.4, the O2 voltage readings shoud be bouncing around not steady. Also, look at your O2'S B1 & B2 % values. They should be bouncing up and down in value every second or so as your PCM adjusts your fuel trims. Other than a factory manual, a parts store repair manual will not give you the proper values.
I agree with the dealer, you do not have a Cat problem, you most likely have an O2 sensor problem. Before you go throwing a bunch of O2's in there, be sure you do some research on upstream and downstream O2 Sensor's and what there function is.
As far as your scanner telling you that B1 S1 is a negative -7.8, that tells me the upstream O2 Sensor is reading lean (- side) and telling the PCM to dump more gas in. My B1S1 & B2S1 readings are continually bouncing between -3.0 to + 2.5. The sensors are continually having the PCM adjust your fuel trims. When I get into the pedal a bit, my readings will increase in value. I have never seen my truck post a -7.8 but for the Expy, that may be normal.
I really hope you bought the scanner that gives you continual live data readings. If it is giving you just straight values without showing you continual adjustments, I'm afraid the scanner is only really good for turning off your CEL, and erasing the codes.

I suggest you get the fuel filter changed ASAP.
Your #7 misfire may be related to the bad gas and screwing up the injector or the plug. You could swap out the #5 and #7 injector's as well as the COP's and see if you can transfer the problem to the the #6 cylinder. That will narrow it down for you.

6 weeks ago, my Mom's jeep was running a bit crappy and kicked out the Cat low eff. code. I slammed 2 bottles of Lucas in it, turned off the CEL and it ran much better. 4 weeks ago it was still running good but the CEL kicked out the same code. On Jeep's you have to change either the S1 or S2 O2's and somtimes both. My experience is to start with the downstream (S2). Easier to change and usually cheaper to buy. 4 weeks later, the Jeep runs great and the CEL did not return, and all of her monitors are steady green (good)

Good Luck, keep us posted.

 

DBL post, sorry

 

I re-read your post.
Your B2 S1 , O2 Sensor should be between your exhaust manifold and ahead of your 1st CAT on the drivers side.
That is your upstream sensor.
When I did my Mom's jeep, I sprayed the heck out of the threaded area of the O2 where it connects into the exhaust "bung", with PB Blaster and let it sit over night. I sprayed it when the exhaust was hot and then went back out an hour later and re-sprayed it after it cooled down. That stuff works awesome.
The next morning, it came right out, with very little pressure with an open-end wrench.

Good Luck !! Keep us posted.

 

The downstream O2 sensors only monitor the cats - and should not affect the way it runs, all they will do is trip a CEL. If you replace the upstreams, get OEM or Bosch.

 

I appreciate the great responses. It sounds like everyone concurs that it probably is the O2 and worth replacing one to see if that does solve the issue? I have my own horror stories of chasing problems and spending LOTS of dough only to find out it was a simple fix. (One example of many: Had a GLH Turbo that keep stalling at odd times, relaced every sensor etc under the hood piece by piece only to have it recur weeks later, turned out the in-tank fuel pump overheated whenever fuel got below 1/4 tank and I just never noted the correlation of fuel level! New pump, and kept it above 1/4 tank after that!)

I bought an Innova 3130 ScanTool CanOBD2 that does show live streamng data. Without a manual I had no clue what the values should have been reading. I can use it to record 20 frames of live data triggered either by occurence of a DTC or manually, with an option for 20 frames before, after, or centered around the trigger. I'll set it to the 10 before and 10 after the DTC gets set and drive it until it happens so I'll have a snapshot to look at in more detail.

Again, thanks to all for the excellent info!

 

As soon as the assumed bad tank of gas was used up and had 20 gallons of presumably decent fuel, I changed out the filter once I finally found the silly thing hiding in front of the tank under that cover!

 

Very easy to get to by getting wheels on ramps and scooting under drivers door. The wrench could only get 1/12 turn so it took a few flips pf the wrench but still less than 5 minutes overall! The Checker folks did not have the Bosch OEM sensor without ordering, only a generic without a connector. I needed to get it done today so I went to the dealer who only too happily gouged me for $120. But it made a huge difference, no rich smell, runs much more smoothly, and gas mileage is back in normal range.

Still getting an occasional misfire on cyl 7, so once it coools down I'll try swapping 7 with another one (whichever is easist to get to!). Hopefully I 'll find an article on this forum that explains any tricks that might be involved...

Again, the help was greatly appreciated!

 

Swapped injectors for cyls 5 & 7 - now getting misfire on 5 but no longer on 7(and still too rich on Bank 2), so ordered new Motorcraft injector for $51 from local Checker auto parts. Apparently the bad gas, or the fuel dryer/octane boost/injector cleaner, managed to screw up both the O2 sensor and one injector. The old O2 sensor has a LOT of carbon in it.

I am using Chevron's system cleaner that has Techron in it, but have no clue what product my wife initially dumped in the tank as a fuel dryer.

 

If you have less than 120,000 miles, all this stuff is covered under warranty (extended coverage campaign 07M08), you know...

And swapping leaking injectors from cylinder to cylinder, you've probably caused more harm than good to the engine. The P0430 is from the injector dumping raw fuel into the exhaust.

 

I use the same scanner. I did alot of research before I bought mine and have not been disappointed. I bought it in March and I have already fixed some issues with my truck and some other vehicles in the family, It has paid for itself and then some.

The downstream O2 is only going to correct the CAT effiency code. That's the O2 that I changed on my Mom's jeep to get rid of the CEL. Hasn't returned a CEL/code since I replaced it.

 

Only drove it less than two miles, and will not drive again until I replace the bad injector.

Warranty coverage would be great, but the dealer tried to blame a non-warranty item and charged my wife $104 for his "diagnosis" of a faulty fuel tank level sender - no repair labor or parts. (She plans to call AMEX and disallow that charge.) I suspect they would have hit us up for well over $1000 by the time they returned the truck, and I am skeptical they would have solved the problems. Admittedly, I am biased against dealers based upon a loonnggg history of incompetent pricey "service" on many vehicles - GMC, Dodge, & Ford dealers I have used have all been guilty of what would qualify as medical malpractice had they been doctors. When I have the time and resources like this forum, I get better results much more cheaply avoiding dealers even when it is supposedly warranty work.

 

O2 sensors rarely if ever are the cause of cat efficiency codes. If anything, the P0430 says the sensor is working.

 

Do not want to start any trouble, and I respect that you have been a long standing member and have offered excellent advice.

When I pulled out the Jeep manual and read the possible fixes for eliminating this code, it stated that I needed to replace the Bank2 S2 O2 sensor.
To confirm my finding's, I called my local Jeep dealer and he said they recieved a bullentine from Chrysler to replace both on Bank2 to correct the code. He said that replacing S2 O2 would most likely correct the issue and for 4 weeks now it has. Prior to that, the CEL would come on every 1 to 2 weeks. The last 2 times the CEL came on it output P0432.

A little confused with your statement. For my own education, could you explain your statement with more detail.

Thanks,
TJKinCNY