Out of curiosity, do you let your truck idle a lot? For like a month I would let my truck idle for 20 minutes during the winter to stay warm in the mornings at my high school parking lot, and my gas mileage dipped to 9 miles per gallon

 

Not really no. I like to remote start it when Im walking over to it just to hear it fire up ha but other than that two maybe three min at the most before I drive off. With all this extra time ive had i went through my notes where Ive stored every code that my truck has thrown ( That I can read by turning the key three times). It once had a misfire p0300 which was solved by replacing the crankshaft position sensor and the old one was definitely broken. I also had a tough time getting the truck going one cold day ( around -27 C I believe it was.) I had codes P 2017, 2110 , 2072. I have never had these codes come up again since that day. I do have an intake manifold off of our parts truck that i guess could be used to "fix" P2017 but I really do not want to replace it as it was very time consuming to rip it off of the parts truck. And ive never had that code come up again. Its not very common but I do sometimes have a rough idle usually followed by a hissing from the A/C? could something be up with that?
Again any help is appreciated.
Thanks

 

If you've got a lot of time on your hands, you could educate yourself on how the computer makes fuel and timing advance decisions. Realizing the tune probably going to nullify looking at the parameters for oddities, you might monitor another unmolested vehicle to see how it works. If you have an android phone, you can use the torque app and a cheap bluetooth obdII reader. Amazon isn't showing fast shipping these days, so maybe get it from a seller that is going to process your order quickly.

This guy explains things in decent detail... there are probably plenty of other sources as well.

 

I wouldn't bother with going back to a stock tune, with the mods to your exhaust (headers and no catalytic) and a CAI you are better off with the aftermarket chip as a stock tune would only make a difference if you went back to a stock exhaust by taking the headers off and putting a catalytic back on (which I wouldn't do). Your mods should give you a bit better fuel mileage with the chip. Do you know what type of chip it is? Depending on which chip you have, using a different octane gas will help if the chip is tuning for a certain octane other than the one your using as some have mid grade or premium tunes, but some are for use with just regular octane gas.

What type of CAI do you have? is it near or in the fenderwell or is it close to or over the engine? If close to the engine its getting warm air and hindering not helping but if its away from the engine with a shield or in the fenderwell that should give you slightly better gas mileage.

 

I have no idea what chip it is, it came tuned with one when I bought it. Since gas is 59 cents a liter up here in Canada I did throw a tank of 91 octane a couple weeks ago just to see if I noticed a difference. I was on the gas light when i filled it up to ensure that it was as pure as I could get it and it made no difference unfortunately. Its a Mopar CAI (I believe) and it is right up against the firewall with a heat shield. Plus I have a functioning hood scoop (srt hood) that funnels right into the filter. Our part truck (same exact truck) with all the same mods was on a super chips tune for a bit until my dad felt it wasn't worth the money for premium. So he turned it back to stock years ago and it just did soo much better on gas then mine. I know they arent fuel economy vehicles at all but its just brutal. On a side note I just checked the resistance of the injectors using the 200 Ohm setting and all 8 ranged from 12.8 - 13 ohms so I dont believe its an injector issue. Do you know of anything else I can check?
Thank you again

 

Ive heard a couple things about closed and open systems? When a vehicle is first started its in a closed system until it is warm or used to its surroundings? To my knowledge it runs a little richer during this time? Is it possible that maybe my truck is staying in this closed system because of something to do with my Rad? It always gets up to temp and stays just below the half way marker but I have no idea when the coolant was last flushed. Is it possible that by flushing the coolant or changing a thermostat that it could fix this issue? The other thing ive heard is that bad fuel filters can cause bad fuel economy. Does my truck have one of those and where would it be? Is that a possibility?
Thanks

 

At first startup, the truck runs in open loop, and the PCM injects fuel according to tables, based on various sensor inputs, at this point, it ignores the O2 sensors. After a couple minutes, O2 heaters will have them hot enough to operate properly, and the PCM starts paying attention. That is what is referred to as closed loop. So, if the engine runs great for the first couple minutes, and then starts acting weird, that indicates failing O2 sensors. They won't necessarily set a code. They have quite a few failure modes that make the truck run like crap, but, so far as the PCM is concerned, everything is just peachy. Even though it's not.

If your sensors are old, replacing at least the front sensor(s) is a good plan. NTK or Denso sensors only though. These trucks don't like the Bosch fellers. (or any other off brand for that matter.)

 

That makes sense. Is it only the O2 sensors that will "close" the loop when they get hot enough? I did replace my upstream O2 sensors with NTK just a few weeks ago.
Thank you

 

Actually, there are several things that have to happen, engine temp has to be above some specific value, O2 sensors need to be 'ready', and probably a couple other things as well, but, it all comes together fairly quickly.

O2 sensors have the biggest impact on fuel economy though, so, changing them out was a good plan, and you got the right brand. I don't know if resetting the PCM after changing them is absolutely required, but, it probably isn't a bad idea. Let the PCM re-learn the engine with all the new stuff.