Crip says:

OK, I've been noticing what feels like a miss at low speeds, about 30 MPH is where it's at, but if I gas it, the van will jump quick, as if nothing is wrong at all. Auto zone got a P0174 code during a test while running, any clues, someone else has had to have gotten this code at some time. Why is it doing this only at low speeds, my MPG is a staggering 6 to 7, getting really expensive, but I can't afford repairs at a dealer.
If it is my EGR valve, that was the other code:P0401, should I replace it or get it replaced, remember, my van has it in a difficult to get location?

izzy jr says:

do you have a 5.4 in the van? And when was the last time your plugs/cop's were changed out? MY 01 Screw w 5.4 acts that way about every 6-8mo's and it is usually cause the #7 cop has crapped out and is causing a misfire. I would go to a different autozone and have them do another scan and tell you what codes are stored before throwing parts at the truck

Crip says:

Just the 2 codes I posted, I'm betting it could be the EGR, it runs great otherwise, had the plugs done at 98,000 and has under 120,000 on it now. Thinking about buying a EGR sensor first, since the valve itself is $106, do it after resetting the ECM and taking it for a drive after replacing the sensor.
P0401
P0174

turbotuned says:

When I google P0174 the info I get from OBD-codes.com is:

What does that mean?

Basically this means that an oxygen sensor in bank 2 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 2 is generally the side of the engine that doesn't have cylinder #1.


Causes A code P0174 may mean that one or more of the following has happened:

The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor.


Possible solutions include:

In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace if necessary
Check for a dirty fuel filter and proper fuel pressure


Note: This DTC is very similar to P0171, and in fact your vehicle may show both codes at the same time.

Crip says:

P0401
EGR system fault
The ECM has detected too little flow on the EGR system

I replaced the DPFE, basically it is what causes the EGR problems, it's rarely the valve itself. Wasn't too bad to get to, the solenoid would be easier as it's on the rear, it was the first thing I noticed upon removal of the doghouse. I plan to pull the battery cable and Q-tip the MAF tomorrow when I get up, take it on a drive and then back to Auto Zone for another code scan. I think I could feel a faint difference tonight in it on a short trip out. I'm gonna buy the cleaner for the MAF while there and get help to clean it, I hate fooling with my filter, the housing is hard to get back on and latched back from my chair.
The sudden drop in MPG is what got my attention, BTW I run 1/2 tank of E-85 with 87 octane regular unleaded, may cause an improper O2 reading due to it burning cooler, I expect that. I wish I had gotten it scanned before fueling it up, previous tank was regular unleaded, the poor mileage had me worried.

izzy jr says:

crip,
have you also checked the pcv valve as it is also tied in with the DPFE/EGR sys and is on $3-#4 at most to swap out, or you could just pull it out and clean it with elec connector cleaner or brake cleaner

Crip says:

Swapped the switch out last night, runs better now, didn't think I'd notice, gotta pull the battery cable to drop the codes, then get it scanned again. Cruised doing 25 through the neighborhood coming home, no more stumbling.

Paco says:

Mine is doing this too... what switch did you replace?

Crip says:

It's called the DPFE, get the codes checked, it's part of the EGR circuit.
BTW, I have a fiberglass hood scoop on it's way, I'll be cutting my hood and grafting it on when it gets here, ram air is in the works now.

Paco says:

Oh sweeet Mod! I need to check on that DPFE...

Crip says:

Once I can make it to Cloudy's, shaving door handles and porting the fenders, who knows what else.