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Discussion Starter #1
I have a 2011 Dodge Avenger Mainstreet (4 cylinder) with 158k miles. Over the last year or so I’ve noticed my MPG dropping little by little. It has dropped all the way down to 17.8 MPG!!! My inclination is that it’s a fuel/air issue but I’m not sure, leading me to get some advice from some pros on other things that I can try. So far, I’ve done the following;

~fuel system/injector cleaning
~MAP sensor replacement
~spark plug replacement

It should be noted that when I changed out the spark plugs, the old plugs were TOAST! I originally took my car into the dealer to figure out why my car was “stuttering” or “misfiring” on acceleration and going uphill. Clearly, the plugs were the problem as the “stuttering” went away after changing them out. Still, after changing out the plugs and fixing the “stuttering,” the MPG continued to drop. Also, there are NO CODES being thrown! I’m close to taking it to the Dodge dealer to diagnose it, but I’m afraid they won’t be able to diagnose it without any codes and give me a bill for hundreds of dollars and nothing to show for it. PLEASE HELP!! Thank you in advance!!
 

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Discussion Starter #2
It should also be noted that the acceleration is worse with either the heater OR A/C on (as expected), but it seems worse than it should be. There are times that I can have the accelerator all the way to the floor and it just SLOWLY gains speed and wont downshift. Other times, it will slowly gain speed with my foot to the floor and downshift with SUPER high RPM. Not normal.
 

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Very hard to give insight with no codes being shown. With the "stuttering" the CEL should have been flashing denoting a misfire and codes set for that. Don't know what normal maint. has been done during it's close to 160k mile lifetime, but there was a recall for cat converter recently released for the 2.4 motor cars. But does sound like a plugging up converter from your description. Which could have been caused by a leaky fuel injector dumping fuel instead of spraying the fuel. Good luck!
 

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Very hard to give insight with no codes being shown. With the "stuttering" the CEL should have been flashing denoting a misfire and codes set for that. Don't know what normal maint. has been done during it's close to 160k mile lifetime, but there was a recall for cat converter recently released for the 2.4 motor cars. But does sound like a plugging up converter from your description. Which could have been caused by a leaky fuel injector dumping fuel instead of spraying the fuel. Good luck!
Surely, a “leaky” fuel injector would throw a code, right? That’s the most maddening part about this issue. ZERO codes have been thrown!
 

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A code? , Not always as you're finding out already that no codes are showing yet horrible engine operation. Keep us all here informed on what you end up finding the trouble cause!
 

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You could start with giving the throttle body a good cleaning with Seafoam spray.
 

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Discussion Starter #8
A code? , Not always as you're finding out already that no codes are showing yet horrible engine operation. Keep us all here informed on what you end up finding the trouble cause!
In theory, could the old spark plugs (again, they were TOAST) have damaged the CC? I’ve been reading other posts regarding CC’s and I’m just curious if that could be the case.
 

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Run a can of Seafoam thru the gas tank. It will clean injectors, plugs, cylinders, O2 sensors and the CC.
 

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Discussion Starter #11
UPDATE

Just got off the phone with the Dodge dealer and they said I had two recalls that needed to be addressed, one being of the safety restraint type and the other being the CC! I take it in on Thursday so hopefully that fixes it. In the meantime, I’ll clean the throttle body.
 

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I’ve heard mixed opinions on Seafoam. Are there any cons to running Seafoam through the system?
When one FOLLOWS the DIRECTIONS on the bottle and does not "overdose" it...it is a very effective treatment in the fuel tank. What member Intrepid suggested using was another of their products in a spray can ... much like spray cans of Carburetor cleaner to clean the air intake throttle body. I've used Seafoam for a great number of years as a fuel system cleaner in the gas tank and had great results with NO harm ever being done BY THE PRODUCT. What it can't do is fix a too badly fouled out injector of an engine...that requires replacement...sorry it is NOT a "cure all magic bullet".
 

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I have used Seafoam for many years and no issues. Just like 5rebel9 stated, when one Follows the DIRECTIONS on the bottle and does not "overdose" it. When I owned my 2005 RAM 1500 with a 5.7 liter HEMI, I would remove the throttle body every 30,000 miles and bench cleaned it. It was super easy to remove 4 10 mm bolts and an electrical connector and it was off.
 

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I use Seafoam (via the gas tank) in all my vehicles. I buy the gallon can from advance auto with a 25% off coupon they send in the mail. Makes it much more reasonable price wise.

I even put it in small engines (mower, atvs, generator) a couple times a year.
 

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Discussion Starter #16
UPDATE

Took the car into the dealership to have the recalls taken care of. However, they were only able to complete the safety restraint one because the CC was on backorder. Wasn’t pleased with how the service department treated me so I called a different Dodge dealer in the area and they were much more accommodating and said they would call me as soon as the CC showed up. So, no CC yet.

I did, however, shine up the throttle body and dump a can of Seafoam into the gas tank. Throttle body didn’t seem all that dirty. Took it for a spin after cleaning the throttle body and dumping the Seafoam in but didn’t notice any real difference in performance. I’ll keep taking it out and get the Seafoam to take more of an affect. I’ll post another update if there is any real difference or the CC shows up and gets replaced.
 

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At 158k miles you might be due for a new throttle body. They do have wear points and yours could have some of these. Bushings on the butterfly plate, motor and maybe a few others. Crank sensor as well as cam position sensors can cause issues without codes, been there done that.
 

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Discussion Starter #18
At 158k miles you might be due for a new throttle body. They do have wear points and yours could have some of these. Bushings on the butterfly plate, motor and maybe a few others. Crank sensor as well as cam position sensors can cause issues without codes, been there done that.
I changed out the crankshaft position sensor a little over a year ago. I did change out the camshaft position sensor today though, but didn’t really notice any difference. I guess I’ll start looking into a new throttle body...
 

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Discussion Starter #19
Ya know, I noticed something that sort of sounded like it was rattling around inside of the “box” connected to the throttle body. Whatever was making the noise may not have been fully free. With that said, is that “normal?” Looking on RockAuto (link attached below), I noticed that it mentioned that some units must be “relearned.” Does anyone have any experience on weather or not the unit will require a “relearn” process, and if so, how difficult is it to execute?

https://www.rockauto.com/en/catalog/dodge,2011,avenger,2.4l+l4,1447805,fuel+&+air,throttle+body,6472
 

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Discussion Starter #20
Haven’t had any suggestions or insight from anyone, so I figured I’d give the thread some life. The dealership still hasn’t received the new CC for the recall, so no news there. Also, my battery needed replacing last week. I’m sure it’s pure coincidence that the battery died two days after I changed out the camshaft sensor but I just figured I’d mention it. Pretty sure it was the original battery too! What a pain to change that bad boy out.

Anyway, looking at the options for throttle bodies on RockAuto (link in my previous post), I was hoping someone could give me some insight and perhaps experience with those manufacturers. Right now I’m leaning towards the one manufactured by Standard Motor Products, Inc. Suggestions, please and thank you!
 
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