High Idle / Emissions Problem

[steveofg27]

I have a 98 ranger, 2wd, v6 3 ltr, Vin -U. I've replaced the thermostat, egr, ecg, 2 o2 censers and some fuses. The only check engine code coming up is P0401.

My exhaust does smell rotten but I have several catalytic converters. The code doesn't narrow it down for me. Is there any other, less expensive suggestions out there? I'm burning too much fuel idling. I used to get 330 miles a full tank and now it's less than 300 miles. I also replaced the water pump and flushed the system out.

I am open to all suggestions please. The truck is in great shape other then that one issue.

Thanks guys.

 

[adsm08]

High idle usually means air getting in somewhere it shouldn't. That would also be supported by a drop in fuel economy, however miles per tank is not a very accurate measure, as not each tank is the same size. Better to calculate MPG.

P0401 is insufficient EGR flow detected. That is normally due to a bad DPFE sensor, but in your case I would start by inspecting the vac lines running to the valve and solenoid.

 

[black_demon69]

High idle usually means air getting in somewhere it shouldn't. That would also be supported by a drop in fuel economy, however miles per tank is not a very accurate measure, as not each tank is the same size. Better to calculate MPG.

P0401 is insufficient EGR flow detected. That is normally due to a bad DPFE sensor, but in your case I would start by inspecting the vac lines running to the valve and solenoid.

+1

 

[jeremysdad]

MPT can also be affected by gas quality from station to station, and even something as simple as air pressure in tires with changing seasons, and changing temperatures...cooler air+more fuel. More power, though, so there's that!)

Just tossing that out. Agree with above statements. Wtf is a DPFE? (Note: I know what that is...I chose my truck because it didn't have EGR. Also only paid $2500...I remembered incorrectly in another thread. lol)


Rep me, bitches! Or I keel you for fun!

 

[steveofg27]

Thanks guys, I'm going to check those 2 things and I'll get back to you. But what is your thought on the cats?

 

[SPSully]

Is it high idling while on the brakes at stoplights and such? If you start the truck and put it in reverse, does it high rev without putting any real pressure on the gas pedal?

 

[steveofg27]

All great suggestions. The weekend is here so now I can really get under the hood and check out some of the suggestions.

Would the coolant temp. sensor have anything to do with it?

I haven't noticed high idle while in reverse. But when I come to a stop light and drop it in neutral the rpm's stay high. I have to use the clutch to drop lower the rpm's.

On the notes about gas.... I only track mpg's when I completely top off and reset the trip gauge. I do take into account driving in the city, if I'm hauling a trailer and so forth.

But I'll update you all after I check it out.

Thanks again guys.