im getting an P0171 engine code since i swaped an engine on my van about 10 months a go! My fuel consumption is terrible and don't know what to do. Please help me!

 

Usually, when you swap engines, you also get the computor from the donor vehicle. That way, you keep the computor and the engine matched up together. If you get the computor and engine mismatched, it can cause problems.

Elsewhere, you might check the 02 sensor, see what it's doing. I'm not saying replace that sensor. You just need to look at something, to see what is going on. See if the sensor is showing rich or lean, see if it is switching.

 

Here is another question, how do i burn almost 80 L of gas in no more than 200 Km driving an avarage 60 - 80km/h and construction site? What do you think, cause i don't remeber when is the last time i got 500+ Km on a full tank. And i do not tow anything or carry heavy loads. its usually just me! PLeasse respond. The Gas Is killing me as well. Thank You.

 

p0171 code is System too lean bank 1
bank 1 is the side of the engine with the number 1 plug
lean conditions can be caused by numerous things, usually air leaks, wether it be vacuum lines or intake gaskets.
it can also be caused by faulty 02 sensors, or a bad catalytic convertor. you need a real time scanner to monitor the o2 sensor switching cycle times and verify that it is switching a it should, check for vacuum leaks also. take a can of carb cleaner and spray around the intake base and listen for the engine to miss or stumble, then spray around any vacuum hoses. if the engine stumbles, or may even rev higher in some cases, you have a vac leak.
the reason for the low fuel mileage is the pcm is seeing this lean code and is dumping fuel into the engine to compensate for it. fix whats causing it to go leans and your mileage will increase dramaticaly.

 

oh, and to add...on a chrysler/dodge, you cannot swap used pcm's to the vehicle from the donor car. they are imbedded with the vehicles vin number. if you try to install a used pcm from anoter vehicle it will not start, youll get a code for vin mismatch. the only way to replace a pcm is to buy a new one and have your vehicles vin number programmed into it. otherwise it wont snd information across the bus communications system.