Hi, so I have a 2007 Dodge Caliber SXT, 2.0L engine with 196000 miles and automatic transmission that is hard to start, bad hesitation both from a dead stop and while driving. It has a code of P0171. I was able to fix the other problems it had and clear all the other codes except the P0171. This code could have many answer from what I've read but my handheld scanner is not able to tell me why I am getting that P0171 code. Hope you can help.
You're running too lean. Seeing as how that thing is 17 years old vacuum leaks would be a prime suspect, but you might also have clogged fuel injectors or low fuel pressure. How old are your air and fuel filters? Spark plugs? Have you analyzed live data for problems?
I forgot to mention that the plugs were black and the new plugs that I installed also came out black after 15 minutes of running. My handheld scanner dose not have live data capability. I did look for vacuum leaks but could not find any. Air filter is new don't know about the fuel filter its in the tank with the pump I think.
My handheld scanner dose not have live data capability.
Are you sure? Even cheap scanners these days can display and even graph live data. In any event what you're seeing on the spark plugs is evidence of running way too rich even though that code is for too lean. Either that or the plugs are getting oil fouled. Are the black deposits oily?
Could be an O2 sensor issue, it may be telling the computer the mixure is too lean so more fuel is erroneously being pushed through. Would be nice to see the output from the upstream O2 sensor to see if it's working properly.
Ok this is what I found that when the car warms up about 5 to 15 minutes and you shut it off it will not start again until it cools off. There is a little bit of oil on the tips of the plugs but very little. The scanner I have is the MS309 by Autel, on the display the options are read code, erase code, view freeze frame, i/m readiness, vehicle info, exit. the main screen has setup and enter. Hope this can better help you help me.
he scanner I have is the MS309 by Autel,
That's an unusually basic scanner. I'm surprised, my $60 CGSULIT can scan, record, and graph data. In any event I think the next step would be to check operation of the upstream O2 sensor and you're going to need to dig into the data for that and you'd also want to take a look at fuel trims.
There's always the old-school pre-OBD2 method of connecting a voltmeter to the O2 sensor to check its output but it looks like that's a 4-wire sensor. Probably two for data+ground and the other two for the heater. However I don't know which are the data leads.
Other than that we are left with the obvious symptom that your spark plugs are quickly fouling. I would expect if there's that much excess gas you'd be able to smell it on them.
I found the pinout for that O2 sensor if you want to give the voltmeter method a try.
No there was no smell of gas at all they just smelled slightly like burnt oil and the car does have a little blue smoke when it's revved hard. I think it may be starving for fuel either the throttle body or the fuel injectors or fuel pump. But I don't have the equipment to test those parts.
Yes I will try that I have nothing to lose by trying. Thank You for all your help.
Yes I will try that I have nothing to lose by trying. Thank You for all your help.
Normally the upstream O2 sensor should provide a varying reading between 0.1 and 0.9 volts as it adjusts mixture on the fly. If there is no voltage or constant voltage it is not working properly. (This is assuming it's a traditional-type O2 sensor, not the newer wide-band type.)
https://www.carparts.com/blog/how-to-test-an-o2-sensor/#Digital_Voltmeter_Testing
From your description of the blue smoke as well as the rapid fouling of the spark plugs you may be dealing with a worn engine, which would not be a surprise at that age and mileage. A compression test would not be a bad idea.
Yes that was the first thing I did that is how I saw the black plugs and decided to install new ones which also turn black. The compression test was 150 in each cylinder which told me that the rings were sealing as each were exactly 150.