4.7L V8-2002 Durango SLT

Bought at 103k. Has 117k on it now.
I have: Done the 100k maintenance, all fluids, replaced a leaky oil o ring, replaced exhaust manifold gaskets including several broken bolts, new gas cap, new O2 sensor, throttle sensor, new plugs(autolite-heard not good) AT tires, front brakes and rotors, serpintine belt.

I am bringing this SUV back to life after it was so mistreated. I love the thing now. We are a part of each other lol. Anyway, after attending a regatta a couple of weeks ago I towed friends boat, about 2300lbs total, for about 200 miles round trip. Everthing worked great and burned the amount of full I expected too. However now after 3 recent fill ups I have noticed that my gas mileage has not improved by much. I am stuck at about 11-13 mpg and am accustomed to getting 15-16. I havent done anything different since I have returned. My first thought was O2 sensor again. When that went bad I was getting about 7mpg. There is also a noticeable delay between the time I press on the peddle, rpm to actual acceleration. Its between the rpm and acceleration specifically. And when going slower at say 25-45mph I can step on the peddle and rev about 500rpms before the engine actually accelerates. So, my question to you is what could this be? After having the o ring and new throttle sensor put on about 3 weeks ago everything seemed ok. It was sluggish when I stepped on peddle from a stop to 10-mph like it wanted to flood out. On 3 occasions it stalled. I am using autolite plugs. I heard that wasnt so good for these rigs but the previous werent even replaced at 50k I am betting, they were so bad. Could this be a cause? The coils? Perhaps the O2 sensor again? do they really go bad twice? I got that from NAPA. I have yet to get the engine light checked. Going to do that this weekend. That came on not to long ago, again, but its been on ever since I got it. Evap leak, all the time. Could be something new, but I will let you all know when checked.

If anyone can come up with anything I would sure be appreciative. I am a college student and not full of dough. I save hard to enjoy this vehicle and drive it. It keeps my daughter safe as well driving a large brick around. Thanks in advance for the help.

 

if you are checking your mpg by the overhead console, IT IS WRONG!!!!!!!!!!! you need to fill the tank all the way and reset the trip meter, drive it for a while, get gas again (fill it till the pump shuts off) now take the mileage on the odometer, and the number of gallons you just put in and divide them, this is your average mpgs.

i am sure that master tech will chime in on the transmission shifting issue, but i will tell you to check the fluid and make sure it is full (engine running, after driving 8-15 miles, flat service, trans in neutral) if not fill it up w/ ATF +4 transmission fluid AND NOTHING ELSE!!!!!!!!!!!!

and get that cel code for us, you should be able to pull it out yourself by turning the key to on (not start) then off-on-off-on (three times) and then the odometer window should flash the code (its a little bit tricky to get at first)

 

So, I got the sequence to finally work for getting codes this morning.

P 0132: 02S shorted to voltage. As I said I had a new O2 Sensor replaced about 6000miles ago. Also just had a new battery put in with 810 cold crank amps(les schwab). So, how many O2 sensors are there and could it be the original I replaced by chance. I read on here that for these you should use the OEM sensors only. I read that after I purchased mine from NAPA.

P 0442 Evap Leak monitor medium leak detected-How big is medium and where I am not looking?

P0456 Evap leak monitor small leak detected (0.020)- Again with this code. .

I have had the evap leak since I have got it. I didnt know there was two though. As I said I have had 3 bolts replace below, and according to the 1st mechanic I took it too, he replaced the exhaust manifold gaskets, I think, I definately bought them and handed them to him. I am beginning to wonder. Where else would this take place on 2 levels? I have replaced the gas cap as well.

Shrpshoter325, I always check my mpg the way you are suggesting. Thats how I know I am accurate and not bsing myself.

Whats the word on the fuel sender/filter unit on these things? The local dodge dealership service center said that they last a LONG time and that it will more than likely just die instead of starting to go bad. I dont know about this. Thanks again for the help and suggestions.

Oh yeah, checked transmission fluid after having drove for 15 minutes, in neutral and its good.

 

this could be any one of the 4 o2 sensors that exist on the 4.7l Durangos (one pre and one post cat on each bank of cylinders). The best bet is to replace them with OEM parts from the dealer, the aftermarkets dont tend to last very long.


this sounds like they are probably one issue, could be as simple as a bad gas cap, could also be cracked hoses on the charcoal canister, (located even w/ the drivers seat underneath the truck, the FAQ has a good write up on changing the hoses in it)


the fuel sender/filter unit is expensive to replace and usually does last for a very long time, however they DO go bad just like anything else and can slowly die, or all of a sudden, but i dont think that your symptoms fit a bad fuel pump unit, jmo, since evap codes can cause all manner of odd things to happen.

 

So how do I tell if the O2 sensors are bad? Will they look a certain way? Is there some way to test them? Or do I simply need to pull and replace each one. I can't imagine its the same one as before.

I replaced the gas cap with a new one a few thousand miles ago. The light when off. Then in two days time it came back on for the same reason. It never read (medium) leak before. Other than the broken bolts I have fixed and hoses to look for. What else can I be looking for that may cause this. I am still new to researching and looking into my vehicle like this. I seem to trust my own instincts more than most mechanics I talk to and so far I have been logical an spot on. Partially with sound advice I have received in this forum. So thank you very much everyone.

 

Where are the 2 O2 sensors in the engine area? I found the 2 before and after catalytic converter. I consulted my manual and it is kind of unclear to me where they still are? Any hints?

Also, I replaced a broken hose going to the Charcoal canister. Thank you for the tip. All the other hoses check out ok now. No holes, cracks or other form of deterioration. The hoses to the evap purge solenoid look ok. How often do these things go bad and if they do, would they get the same kind of code as small and medium evap leak?

 

there are 2 sensors pre cat, and two after the cat (one on each bank) they are not in the engine bay itself(exactly) they are on the exhaust pipes on either side, i fyou follow the pipes you will find the sensors

 

It keeps getting more difficult. I called my local dodge dealer to price an OEM O2 sensor. $100. I figured it would be about that with mark up. He told me it depends on which one though. That if it is California emissions there will be a left and right before and after the cat as you suggested (4 total). And 2 total (1 before and after cat) as I am seeing on my vehicle if it is standard. That being said he tried to tell me that each sensor is different so it depends on which one is bad. Does this sound like horse s*** to you? I have been reading alot about these lately and in my after market manual plus online readings I have not found anything to suggest that there are different kinds of O2 sensors in each slot. I purchased and replaced the one before the cat from NAPA autoparts and they didnt say anything about that either when I was asking questions. So, I guess what I am saying is I am even more confused than before. I thought I could just pull and look (see if its tan) or do a meter test on it as per my after market manual to see which is bad. Plus, I told the guy at the service center what the code was and that it was the O2 sensor. He said "no, that just tells us where to run the diagnostic. Not that the sensor is actually bad." While he may "technically" be right about that, I cant believe he took me for an idiot when I told him I was losing 3-4 miles a gallon and that I think this is it because it happened before. UGH!!! Sorry I am just venting. Im getting frustrated. What I thought was going to be a routine fix for an O2 sensor just got out of hand with the service center/parts dept. input.

Any advice again on how to procede would be great given this new lovely info from the dealership. I am still going to go through with my original plan then and test the rear one I can find I suppose and go from there. Thanks for letting me vent and get this off my chest. Being a college student and single dad I dont have alot of options as far as price goes which is why I am trying to do everything myself.

 

if you have lost mpgs it will be the pre-cat(closer to the engine) sensor that is gone bad, i have never had to replace the sensors on mine (yet, watch me be out doing it in the snow this winter )

 

So this is interesting....I replaced that hose to the charcoal canister like you suggested....thanks for the tip on looking there. I had no clue about that thing even being there...lol. The other day the engine light turned off. Remember is read small and medium evap leak plus O2 sensor. Well, I went and picked up the sensor. Everything is back to normal. I didnt do anything other than that hose. I lost 3-4 miles a gallon on 2 fill ups. Well, after the 3rd fill up and the engine light off I drove around a bit then refilled. I got an astounding 18 miles a gallon. Yes I changed my driving habits, but this is the best I have recorded to date. Not sure what to think about the O2 sensor issue working itself out, but there it is. Oh and I installed a cold air intake the other day...hehehe. Sounds awesome.