cgmart

Hi all,

I am hoping someone can help me. I have recently been having some trouble with my 3.6. She has ~75,000km.

MPG has dropped by 2-3, acceleration seems stiff and shaky/hiccupy at times, engine feels like there is drag in all gears and a lower idle. An isolated symptom i had was when going constant highway speed my RPM dropped by about a 1k and instantly came back up(sounds electrical to me). I have no codes and never have.

From everything i have read the likely culprit seemed to be pointing to intake. So i checked the throttle body and it has a film of oil and debris on it (see images). The IAT sensor seems to have some of this oil on it at as well. The newer 3.6 i find mixed statements about actually cleaning a throttle body. Some say no, others say when you change air filter. Can someone shed some light on this.

I changed the air filter and that seemed to help all of the symptoms but only marginally. Likely going to change spark plugs as they are to the end of their life. Would you folks change all the wiring when you do plugs?

Since she has never thrown any codes this is driving me nuts. Any help would be great. Going to be taking it in next week but want to try diagnose as much as i can beforehand.

CharlesS

First off.... you need to determine where the oil vapor is coming from....;you can see the oil vapor trail inside the air intake hose. A stuck PCV comes to mind.
You can clean the TB with spray throttle body cleaner.

cgmart

Thanks for getting back to me. I need to do an oil change anyways would it be a good idea to clean the PCV valve or just replace it all together. I guess try cleaning first and replace if it remains stuck?

CharlesS

You can try to clean it, but it would be easier since you already have it removed.... the just replace it. Another component that could have been affected by the oil vapor would be the MAP sensor. This component will affect performance dramatically if it has been damaged by the oil vapor.

cgmart

Ok i will check this too, for the sensors what is the best way to clean or is it best to just replace?

CharlesS

Not sure there is a way to clean the MAP sensor. One of the other members may know of a way to test the MAP sensor.

rob_engineer

one time I had oil in my air filter. Turns out I had been slightly over filling the oil wen I changed the oil. That's another thing the OP can consider. I typically buy a 5qt container and a 1 qt container. Sometimes emptying every drop into the Jeep results in an over fill.

themoneyshot

I think the plugs are recommended to 100k but I pulled mine out at 70k(miles) and a few were way off and oily. I think people leave the plugs until they get a misfire code.

As for the oil I replaced the pcv and that was a pain. I eventually added a "catch can" between the pcv and intake. It collects a few ounces between oil changes (7500 miles)

Priam

Having similar problem with my 2012 Wrangler Sahara Unlimited (auto transmission). RPM's will drop at random times, usually while accelerating up a hill, accompanied by a little kick. No codes or lights. It seems random, or we haven't found a pattern yet. Once it shut off while driving and took several minutes to restart (but this has only happened once). Mechanic and transmission shop can't find problem. I have checked the battery, alternator, and have replaced the computer. Any one have any ideas? I am not sure what my next step should be.

JonesboroJeep

Spray your throttle body with cleaner. Then do a reset of the throttle Calibration Procedure:Throttle calibration can substantially improve throttle responsiveness over "factory standard." Many people notice what appears to be sluggish throttle response or a "dead area" at initial accelerator depression. Throttle calibration can take care of these.

1) Insert ignition key and turn to "ON" (not start).

2) Wait for all idiot lights to go out. Check Engine Light may remain on.

3) Slowly depress the accelerator pedal all the way to the floor.

4) Slowly release the accelerator pedal until it's all the way back up.

5) Turn the ignition key to "OFF".

6) Start the engine.

Most drivers notice an immediate change in throttle response, but depending on your driving style, you may need to repeat this procedure periodically due to the computer's adaptive programming. You likely need to repeat this procedure any time the battery is disconnected.



From <https://www.wranglerforum.com/thread...ration.888666/>