HORRIBLE gas mileage..and bank one is running lean..help please
nomiezvr4
12-13-2006, 08:22 PM
Hey guys I have a 98 T&C with the 3.8 motor. It has fresh plugs, wires and an airfilter. 88,000 miles.
I just bought it a week ago and the other day it threw a check engine light. I believe the code is P0171...which means that the bank 1 is running lean if I recall correctly. Anyways, since the car is averaging around 6mpg(according to the car and my own mpg testing) I decided to check the upstream oxygen sensor because maybe it was shot.
I pull the 02 sensor and it was black as could be. The car is obviously running very rich. Why?
I have checked for any leaks on the intake manifold, intake pipe and everything else I could think of that could've been sucking in air before the intake manifold, everything looks OK.
Funny thing is, the oxygen sensor looked fairly new, like only a few months old. Ive been doing a little reading here and there, and people are saying that the po171 code usually indicates that the fuel pump is on its way out..but will that cause HORRIBLE gas consumption?
I want to check the fuel pressure tomorrow, but I was wondering if you guys could throw me any other ideas...thanks!
Nomie
I just bought it a week ago and the other day it threw a check engine light. I believe the code is P0171...which means that the bank 1 is running lean if I recall correctly. Anyways, since the car is averaging around 6mpg(according to the car and my own mpg testing) I decided to check the upstream oxygen sensor because maybe it was shot.
I pull the 02 sensor and it was black as could be. The car is obviously running very rich. Why?
I have checked for any leaks on the intake manifold, intake pipe and everything else I could think of that could've been sucking in air before the intake manifold, everything looks OK.
Funny thing is, the oxygen sensor looked fairly new, like only a few months old. Ive been doing a little reading here and there, and people are saying that the po171 code usually indicates that the fuel pump is on its way out..but will that cause HORRIBLE gas consumption?
I want to check the fuel pressure tomorrow, but I was wondering if you guys could throw me any other ideas...thanks!
Nomie
RIP
12-13-2006, 09:07 PM
nomiezvr4
12-13-2006, 10:15 PM
Hey thanks for the quick response, but I dont think the Town and country has a MAF sensor. I believe it uses a MAP(manifold absolute pressure) sensor. I'll check the fuel pressure then go from there. :) Ill keep you guys updated..
Nomie
Nomie
Rawtorque
01-03-2007, 08:01 PM
It could be a fuel injector stuck open. Or the coolant temperature sensor.
The one bank lean sure sounds like it's trying to make up for a rich injector. ALso look for leaks in the EXHAUST manifold. Yes, that can throw off the O2 sensor loop.
I think it has both a MAP & MAF sensor. A bad MAP (manifold absolute pressure) will also kill mileage.
You could try (engine & key off!) disconnecting the wire harness to the MAP. This will force the computer to use a fixed value for the MAP. Start it up & see if it runs better. But this will also set a fault code, which can confuse anyone working on it later, so warn them of what you did.
I hope you replaced the O2 sensor since it's probably all gummed up anyhow.
The one bank lean sure sounds like it's trying to make up for a rich injector. ALso look for leaks in the EXHAUST manifold. Yes, that can throw off the O2 sensor loop.
I think it has both a MAP & MAF sensor. A bad MAP (manifold absolute pressure) will also kill mileage.
You could try (engine & key off!) disconnecting the wire harness to the MAP. This will force the computer to use a fixed value for the MAP. Start it up & see if it runs better. But this will also set a fault code, which can confuse anyone working on it later, so warn them of what you did.
I hope you replaced the O2 sensor since it's probably all gummed up anyhow.
Steve J.
06-19-2014, 04:59 PM
PCV stuck open? That would probably effect both banks though.
RIP
06-21-2014, 02:59 PM
Hey thanks for the quick response, but I dont think the Town and country has a MAF sensor. I believe it uses a MAP(manifold absolute pressure) sensor. I'll check the fuel pressure then go from there. :) Ill keep you guys updated..
Nomie
Yup. MAP. Serves the same purpose as the MAF. They say the MAF/MAP sensor but I've read more often than not there's a vacuum leak downstream of the sensor if it's a MAP related problem.
Nomie
Yup. MAP. Serves the same purpose as the MAF. They say the MAF/MAP sensor but I've read more often than not there's a vacuum leak downstream of the sensor if it's a MAP related problem.
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