I have a 1998 ford e350 5.4L extended van with 140,000 miles. The check engine light is on and it just failed emmisions test, I am guessing that the O2 sensors are bad. I figure with that much milage I should change them anyways. I replaced the 2 before the cat ( thats closest to the engine ) with Bosh#15716 . But I can't find the O2 sensor after the cat. The service manual shows one sensor just after the cat before the muffler on the top of the pipe , but it's not there, no wire either.
I read some place that some models don't test the emissions after the cat but that's not what my service manual shows.
Does anyone have any more info on this ?



Thanks for your help !

 

Instead of guessing on what to do, GET THE CODES READ!

That will tell you WHY the CEL is on and give you direction for repair the faults in the vehicle.

Post-cat sensors are not used to control emissions. They are there to see if the cat is performing.

Steve

 

Ditto on checking the codes first.

I hate to break it to you, but the E-350 has more than two sensors. It can have three to four. You definitely have two pre cat sensors (Bosch 15716) that monitor bank 1 (passenger side) and bank 2 (drivers' side). Depending on if you have the single or dual cat, (Bosch 15717) you will have the sensor located about an inch after the cat, sitting on top. Silly question, but are you sure you are looking at the catalytic converter?

 

Hi,
I have the 2 pipes coming off the exaust manifolds that is where the before cat O2 sensors are located . those two exaust pipes connect to one exaust pipe that connects to the cat. the output of the cat that connects to the muffler has no O2 sensor . I double and triple checked. As I said before I have the service manual and it shows a after cat sensor in the diagram but it's not on my truck. There isn't even a hole that was plugged up , nothing!
I replaced the 2 before cat sensors because they have 140,000 miles on them and a friend said they should be changed anyway.
The engine light came back on after about 2 hours of driving.
I went to auto zone and asked them to check the codes. It comes up P0171 thats system running to lean. I think changing the O2 sensors helped because my NY state inspection fail for to high Co2 . With this "system running to lean" shouldn't it pass a state emission test now?

I did a search of P0171 and there are plenty of things to check ,
I really don't care if the CEL is on as long as it passes inspection.

Thanks for your help !

 

hmm odd. Follow the pcv line back to the rear of the engine and check to see of the Manifold boot is ruptured. It throws that code all the time. Lean is more air than fuel. Check vac lines and fuel filter.

 

Ok , I followed the PCV line back and checked the elbow/boot connection and it looked ok. I looked at all the vacume line connections and they look good. Are you saying the fuel filter should be replaced? The engine runs fine with plenty of power, wouldn't a cloged fuel filter show up when I tried to accelerate?
I read in another thread that this could be a partly cloged fuel injector should I try fuel injector cleaner in the gas tank?


Thanks for your input .

 

I found something interesting on the missing after cat 02 sensor. I have a 5.4L e350 extended van also known as super duty. If you look up the e350 super duty with the 6.8L there is no after cat sensor. Apparently since my van with the 5.4L super duty is the same body I don't have a after cat sensor either.

I have changed the fuel filter and added injector cleaner.
replaced the pcv valve.
removed and tested the EGR valve ( it was ok)
replaced the DPFE (differential pressure feedback EGR)

I cleared the CEL and will report back after I have driven it 150miles. If the CEL comes on and it's still P0171 I don't know what else to try.

 

syncmaster,

Sometimes the easiest solution is best. The first thing to try to remedy a "lean" condition is to Clean The MAFs..

Bill

 

oops

 

oops

 

Hi Bill,
I forgot to mention I did clean the MAF first, I used a electronic contact cleaner that leaves no residue. It didn't help.

 

As per the Ford Master Service Manual, it can be these possibilities.
Bank on indicates the fuel/air ratio is too lean.

(Note: since it's only passenger side, concentrate on items that are on that side of the block, you can rule out several of these by not having P0174 present)

Possible Cause.

Fuel:
Excessive fuel pressure
Leaking injector
Leaking pressure regulator
Low fuel pressure (possible clog or pump fault)
Contaminated injector
Vapor Management Valve leaking

Induction:
Vacuum Line Leak
PCV System Leak
Restricted inlet
Air leak after MAF
Dirty MAF
Improperly seated oil dipstick

EGR:
Leaking gasket
EGR stuck open.

 

Throttle, Thanks for the info.

since this engine idles so smooth you can't feel it running and it accelerates well with no lack of power, wouldn't that mean that the fuel pump , regulator and injectors are good ?

What on your list would still be possible with a good running engine?


Thanks for your help

 

syncmaster,

I'm an amateur, at best. But if I were you this is what I'd do.

1) Spray some TB cleaner around the intake manifold gasket while at idle. If the RPM rises you have a gasket leak. If not:

2) Check the pressure at the fuel rails. If bank one is much lower than bank 2, there's your problem. Fuel pressure. If not:

3) I would guess one or more of your bank 1 injectors are partially clogged or at least not adding enough fuel. Not enough to cause a miss. But together enough to cause your lean condition. Remove your 4 bank 1 injectors and have them cleaned and tested. I just read that some NAPA stores have the machine to do this. Just bring them the injectors they charge $15.00 each.

Good Luck,

Bill

 

Since you don't have lean codes on both banks, you can rule out pump and filter, but the injectors on the passenger side may have problems. Since you've inspected all the vacuum and PCV hoses, you can rule them out. You might need to find someone with an OBDII monitoring computer, Auto Tap or equivalent, so you can run the vehicle and see if the cylinders are functioning properly. It monitors the engine management devices and can pinpoint most faults. It's cheaper than throwing parts at it.

BTW, there were three different e-350's produced that year and I was finally able to confirm that not all have after cat O2's.