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Discussion Starter #1
My wife was on her way to work today in our '09 T&C with just over 100,000 miles now. Her cruise control was on and suddenly shut off. She pulled over and called me stating that the throttle body/drive by wire warning light was flashing, and the traction control light came on. She told me that it stayed running, but wouldn't go very fast (limp mode?) and so I had her drive it the short distance back home. She said it seemed like the trans wasn't shifting properly on her way back, but she made it back in the driveway.

She switched vehicles and went to work while I hooked up my scan tool and found the only PCM code stored was 2173.

I looked at it and there was a definite vacuum hiss coming from somewhere near the intake area. I tried spraying some electronics cleaner and then some brake clean around the intake, but nothing seemed to help me find the leak. Using my mechanic's stethoscope without the probe, i stuck it under the upper intake plenum, and it sounds like the leak is coming from underneath somewhere. Any ideas? It is too cold and nasty outside for me to do anything with it today, but I was wondering if anyone else had thoughts. I am guessing it is the upper intake plenum gaskets, but I am not sure.

It did have the lower intake gasket replaced due to a coolant leak about two years ago at the dealer we got it from when it was still under warranty. We have been getting the minor evap leak codes since then as well, and replacing the sensing module at the tank didn't fix it. It still comes on from time to time.

Also, since we upgraded her front brakes, the wheel bearings have started getting pretty loud. I have the hubs, axles (the ends are badly corroded near the nuts), and transmission axle seals (they have been leaking since we got it) , and I have just been waiting on better weather to replace them. I don't know if any of that would be related to this issue today though.
 

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Is it the 4.0 engine? Our 2010 with 4.0 had a very loose MAP sensor hose on the fitting on top of intake plenum, near throttle body. It was holding by gravity alone, so I carefully put a small hose clamp on it... The upper intake plenum gaskets did show evidence of vacuum leaks when I replaced them with Fel-Pro, along with Denso Platinum TT spark plugs when it was at about 30,000 miles.

I replaced the leaking hardened OEM axle seals with Timken's. The axles' rough machined sealing surface did need resurfacing and polishing for a proper seal... I also managed to correct rear wheel toe and camber alignment with shims on rear wheel bearing hub mounts when I replaced rear bearing hubs.
 

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Discussion Starter #3
Ours is the 3.8 V6. I changed the upper plenum gaskets last Friday because the ones in it looked original, and the upper intake was loose. Apparently Chrysler wants you to use a medium threadlocker when installing it. I don't know why the dealer that did the lower intake gasket didn't use it, but anyway I torqued all the upper bolts to 105 inch lbs, and test drove it for about a half hour on a state highway and back roads with the cruise on, like my wife said she was doing when it happened last Thursday.

It seemed great afterward, though I did still notice what sounded like a vacuum leak hiss coming from somewhere, but not as pronounced. The spray trick doesn't work at all to try and find the leak, though, if there actually is one. I could be hearing things. It's almost like an AC condenser hissing sound, but with our weather in cooler temps, and not having the AC or defrost on, it can't be that.

My wife reported that it happened again today, again on the highway with the cruise on, and the van went into limp mode. They were able to get home, but didn't find out about it until tonight after a 12 and a half hour shift at the food plant I work in. So now I get to continue trying to fix this.

Just out of curiosity, I noticed when I removed it, there is a sensor that plugs into the top of the driver's side of the upper intake (map sensor?), and it doesn't have anything holding it down. Is that normal, or did the dealer forget to put it on? It looks like there are holes for fasteners of some kind. It doesn't seem like it is leaking there, it sounds more like the hiss is coming from under the intake. I checked it for cracks, or bad sealing joints, but didn't find any. I am quite stumped.
 

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The upper plenum bolts have a torque spec of around 75 inch-lbs. They will snap much tighter than that.

As for your problems; no idea. Smoke test would rule out lower intake manifold leak. Live data fuel trims would probably narrow it down too.

The MAP sensors lock in place by twisting from 3 oclock to 6 oclock position.
 

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I had a 2010 with a 3.8 that was notorious for wigging out the electric throttle body. My wife would pull over and restart the van to continue on her way. I had the dealer look at it multiple times between 12k and 20K miles. I read up on the internet about people having luck cleaning throttle body. So when the issue returned around 30K. I pulled throttle body off and cleaned it with a good throttle body spray. I rotated it in my hands so the electric motor portion was up. Then I used the spray and rags to clean the blade and the bore, especialy around the shaft area. I did this every 20K miles and the issue never came back.
 

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Discussion Starter #6
I don't remember the site I got the torque specs for the upper plenum bolts, but 105 in lbs did seem a bit high for plastic. I will have to try the throttle body cleaning. I also thought a new gasket for the throttle body wouldn't hurt, and maybe a new PCV valve while I'm at it.

The throttle body light does go off if the key is turned off, turned back on, but not started for a bit, and then poof, it clears. Maybe I'll just have her do that if it happens again after all of this. Hopefully it doesn't go into that limp mode. She says the RPMs are all over the place, and the trans doesn't really know what to do with itself.
 

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Discussion Starter #7
Update: So I cleaned the throttle body. It took an e-torx socket to remove it. It was fairly dirty on the intake side with carbon and grit. When I removed the throttle body, I saw that the main gasket/o-ring looked like it had quite a bit of flash on it from when it was molded. I carefully cut the flash off of it as I wondered why anyone would install a gasket like that in the first place. After reinstalling it, it ran and made the same vacuum noise.

Still trying to find the source of the problem, I pulled the forward ventilation hose off of the front valve cover, and plugged the hole in the valve cover with a finger. It built vacuum quickly, and the hissing sound went away after a few seconds, until I pulled my finger off of the hole again. I now think that it is a PCV issue. Maybe it is stuck open.

Also, when trying to order a new throttle body gasket/o-ring, two parts are listed: one is 04593899AA to be used with 04781578AP intake with recessed lip, and one is 04666113AA to be used with 04781578AM intake with flush lip. How do I know which one is which? Does someone have a clear picture of the difference? On ours, it looks like the one installed was the one for the recessed lip, and I would say the intake manifold has a pretty deep recess for the gasket. The throttle body face is completely flat.
 

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Hey Geeshik,

If you give me the last 8 digits of your VIN, I can look up the PN(s) on the dealer service library. Maybe that can shed some light on the O-ring question.
 

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Discussion Starter #9
Last 8 of vin? Ok: 9R630582. I really am curious because another local aftermarket store seem to list the gaskets opposite from the Chrysler site, with the wider one being for the recessed, and the skinny one for the flush mount. Strange.

After changing out the PCV, the hissing sound seems to be gone, or at least quite a bit more quiet. I can actually hear the tick of the injectors or valves now as the most prominent sound when idling. It has been that way since we bought it with about 80,000 miles on it. It seems to be idling the way I remember also. Thanks for all the help.
 
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