Sup guys! It's the dutch one again

So after my last post which was about a coollant leak and mayonnaise in my oil ( which is all fixed ! plenum and intake manifold gaskets where leaking ! )
i've continued digging deeper into some of my problems. One of my biggest ones is the following : i get 7mpg with my 5.2l , i believe this is waaay to much?

What i've replaced so far on this car : rear axle bearings, rebuild tranny, new delco, plugs & wires, new battery , TPS, IAC , plenum & intake gaskets, LPG injectors, LPG electric cables..

Having BF goodrich all terrains on it 285 mm ( 11.2 inches ? ) But can't believe this will add 10liters + with normal useage? i've tried driving a whole tank beneath 2500rpm's and doesn't even differ...

Anyone having any suggestions on what to check/replace or do?

Thanks in advance!

 

What year is the pick up? is the check engine light on? Do you have the ability to read the fuel trims and O2 sensor/s via a scanner?

 

It's a truck from 2000. My upstream sensor has been replaced about 5 months ago.. But i've only fixed my plenum last week. So i can assume my o2 sensor might be reading wrong values cause of the oil that got burned. But when i replaced it months ago i didn't notice any huge differences..

I do have a simple obd2 link sx cable, with some free software on it. But as far i remember i wasn't able to read anything of sensors.. if anybody would know a program that could work with this cable.. let me know !

 

Running on LPG? Not surprising then........

 

Yes running on lpg, but if i compare to others i'm still using way more..

 

Your truck would only get around 12 mpg on gasoline, LPG is cheaper, but, has less energy by volume than gasoline, so, fuel economy drops. I am going to guess that you do not live at high altitude, so that is not really a factor...... You could try replacing the front O2 sensor again, (NTK or Denso please, if you have a bosch sensor in there, they may also be part of the problem......) Also make sure that you don't have any leaks in the system.......

 

Would lpi vs lpg be a big difference?

 

If I understand it right, you would still be burning LPG, just getting it to the engine in a different manner..... I don't think the expense would be worth it.

 

With LPI you should have a slightly better performance, to the fact it's liquidly injected. But the cold gas isn't the best for the valves ( What i read ).

Now, this week i haven't drove the car due to the flue and bronchitis. Yesterday i couldn't resist and fired it up and took it for a lil ride.
Turns out i must have a vacuum leak somewhere.

When i'm daily using it i never hear this sissing/airsucking sound. (airbox mounted with the rubber ring between)
But yesterday when i started the engine, i had to rev or it would die. making the sucking sound... RPM kept a bit hanging each time i smacked the pedal..
Always had this EVAP system leak small and big. ( since i've repaired my plenum 2 weeks ago, the codes are gone and didn't come back yet after 600mile ).

I did break the hard plastic line that runs into the firewall, but i've fixed it and it's not leaking there. So i'll be out on the look upcoming days for the leak somewhere.. Maybe ill just look to smoke my system up..

 

Get a new Mopar PCV valve, the aftermarket ones allow too much flow making it a vacuum leak (sort of). It's to bad you didn't replace the timing chain when you did the plenum. If your coolant sensor reads on the cold side the ECM dumps more fuel. I thought someone said cleaning the air temp sensor helped also.