04 explorer xlt p0191, p2196 and p2198

[nan]

hi
I'm trying to help a friend with a 04 xlt with the 4.0 SOHC, the car idles rough and a bit down on power, sometimes it would die while idling sometimes its hard to start, the CEL is on and when I scanned it with my scan gauge2 i got these codes p0191, p2196, p2198 we cleared the codes but they came back again.

I know what the codes mean but I need any guide on what to look for, and since this model doesn't have a schrader valve on the fuel rail I can't check the fuel pressure.

Is there any easy way to check fuel pressure and the fuel rail pressure sensor? the idea of removing the plenum to check the sensor is not that great

I noticed that the first 1/4" or so of the throttle pedal doesn't seem to affect the engine at all! at first i thought the throttle cable was loose but I found out it's a drive by wire system!

things done so far: new air filter, cleaned MAF, new spark plugs, oil and filter

I checked the vacuum and the engine is pulling a steady 20 inhg so i guess it's not a mechanical problem.

 

[nan]

any thoughts on this??

 

[05XLimited]

Did you change the fuel filter? A clogged one would cause these symptoms. How many miles?

 

[nan]

haven't changed the filter yet, the truck has around 160k miles

 

[05XLimited]

I would swap out the filter, as it is the easiest repair. The fuel system pressure can be tested only by using a fuel line kit, since Ford decided to remove the Schrader valve. If the filter has not been changed at all in 160K miles, then all the junk that has gotten through the filter may have ruined the fuel rail pressure sensor.

 

[nan]

so today i scanned the car with obdlink SX and scanXL pro to verify the trouble codes and take a look at the fuel trim, MAF output,O2 sensor output........ and to my surprise the readings i got don't make sense at all !!

here is a shot of the readings taken while the car is idling


as you can see the ECU reports very high and low (out of range) readings, it even reported speed while the car was parked!

this car had an accidents and the front driver side fender was replaced so i checked the wiring harness, connectors, ground points, fuses but couldn't visually find anything wrong.

what would cause the ECU to behave that erratically? bad grounds? bad ECU? wiring trouble?

 

[nan]

never mind the last post, it was a logging software bug

 

[imp]

I would swap out the filter, as it is the easiest repair. The fuel system pressure can be tested only by using a fuel line kit, since Ford decided to remove the Schrader valve. If the filter has not been changed at all in 160K miles, then all the junk that has gotten through the filter may have ruined the fuel rail pressure sensor.

??? Isn't the purpose of a FILTER to PREVENT all the junk in the fuel tank from getting to the fuel rail in the first place?

The Fuel Rail Pressure Sensor also measures fuel TEMPERATURE, and is a critical sensor to engine operation, so therefore, the PCM has ability to throw several trouble codes specifically aimed at that sensor. The codes shown don't seem to be Fuel Rail Pressure Sensor codes. imp

Edit: OOPS! P0191 IS "Fuel Rail Pressure Sensor Circuit Performance". P2196 and 97 are #1 O2 sensor stuck rich, both banks. Suspect the performance problem stems mainly from the P0191.

 

[05XLimited]

??? Isn't the purpose of a FILTER to PREVENT all the junk in the fuel tank from getting to the fuel rail in the first place?

The Fuel Rail Pressure Sensor also measures fuel TEMPERATURE, and is a critical sensor to engine operation, so therefore, the PCM has ability to throw several trouble codes specifically aimed at that sensor. The codes shown don't seem to be Fuel Rail Pressure Sensor codes. imp

Edit: OOPS! P0191 IS "Fuel Rail Pressure Sensor Circuit Performance". P2196 and 97 are #1 O2 sensor stuck rich, both banks. Suspect the performance problem stems mainly from the P0191.

The filter may have so much sludge and debris in it that it does have the possibility of getting a very small amount through. Many mechanics recommend that the filter is changed every 20,000-25,000 miles. 160,000 (if it wasn't changed) is way too long for that filter to handle.
nan, if you take it for a spirited drive using heavy throttle, does the engine run very poorly, like it wants to shut off?

 

[nan]

it seems to have limited power when I floor it, and the first part of the throttle pedal doesn't do much to the engine, actually if i press the pedal a tiny bit and hold it there the engine seems to start missing a bit so may be the TPS is also faulty

 

[nan]

I changed the fuel filter yesterday, it's a pain in the **** to remove the quick connect fitting, it improved a bit.

while I was there I put my fuel pressure gauge on the outlet of the fuel filter and turned the key on/off 3 times and the pressure went up to 80+ psi so I guess the fuel pump is not bad, dealership wanted $850 to replace it!

then I replaced the TPS, removed and cleaned the throttle body, spark plugs gap was too small at 0.042 so i adjusted them to 0.052 and now it goes much much better

thanks everybody for the help