SOOOO after 9 months, two dealers, 20+ dealer visits, and a chrysler engineer!!!! my truck is fixed... Truck had been throwing code P0174 in cold weather on downhill slope directly after start up...

Well the gold goes to WEEDAHOE he predicted exhaust manifold and ding ding ding we have a winner... manifold gasket was leaking causing air leak when cold..

just glad this is all over and I can go back to enjoying my truck!!!!!!

 

I'm glad you got it fixed, but i don't understand what being downhill facing makes any difference at all? Exhaust gases are pressure and shouldn't matter if the truck was upside down or in water...lol???

 

Maybe Ben can clarify, but my guess is that when going downhill, he is at no throttle condition for an extended period of time, the ECU pulls back fuel as it knows it is in a coasting mode, and this would increase exhaust reversion in the area . Combine this with a leaky exhaust manifold gasket due to the cold, and it allows a small amount of air into the system at the manifold and then throwing the code at the O2 sensor. IDK, but it sounds possible.

Ben, were there drivability problems like it was down on power or something, or did it just throw the code?

 

Good call Weed...

 

my driveway is about 3/4 a mile long and at a 10-20 percent grade it varies down the slope.. So on cold mornings I would start truck.. let idle down since on start up it usually idles at 1200 for 30 seconds then works its way down. Then I'd go down the driveway.

Every time the light came on it was at some point on the driveway. Never just going down the road. Never on a warm day.. Only after the truck sat for considerable amount of time (12 hours or more) and it was cold as in less than 50 out.

according to ramjam that's about word for word what the chrsyler engineer said.
It was pretty much at the point that it was either this or they had no idea what was wrong. The truck has had just about everything replaced that could be wrong with it to cause this code.

When hooked into starscan you could see that the truck right after start up would run lean for a very short amount of time.. enough to trip the light and then immediately thereafter within a few minutes of driving all readings would go back to normal. This was what threw the dealer techs for a real loop because by the time I would drive the truck to the dealer the code would already be moved to stored because it had registered enough clean readings without lean.. A very very odd scenario that resulted in a huge pain in my ***.

New cat/ypipe. PCV valve, at least two sets of O2 sensors, PCM... the lengthy amount of time taken also had to do with the first dealership dicking me over with certain things.

 

Glad you got it resolved and it is amazing how sensitive those O2s are.