Hi everyone, i apologize already if my english is bad. I own a 2009 4L 4x4 ford ranger and i am having issues with my engine. I have no power, it bucks under heavy acceleration and no DTC. I went for a drive while checking the datas and did not find anything suspicious except that my short term fuel trim were at +16, which means it is running very lean. I thought about the catalytic converters being clogged but it wouldn’t cause my engine to run lean ? I also thought about my injectors being clogged or a leaking intake. Or at the worst might be a cracked cylinder head but it would not cause this problem ? I can record a video if it is necessary, thanks a lot 🙂

 

How many miles/km on your Ranger? Are you the original owner? How long have you owned it?
What is the general condition of the vehicle?
Try cleaning the MAF sensor with real MAF cleaner as some electric cleaners leave a coating of lubricant.

 

it has about 180 000km, i am not the original owner, i have had it for about 2 years, it is very well maintained, i am a mecanic, just finished school, it was a project so i did all the repairs it needed except for the a/c, even searched for body panels and took it to a body shop to paint the whole truck. All i know is that the last owner didn’t put a penny to repair this truck. I cleaned the MAF with CRC sensor clean and replaced the air filter before going further. Also cleaned the connectors.

 

I changed the spark plugs, i noticed that the ones on the driver side were more worn out than the ones on the passenger side, i don’t know what it could mean

 

It means someone replaced the plugs using ones which weren't "double platinum".
The polarity of the waste spark system -the layout of which I do not fully understand- causes metal transfer which is different on one bank than the other.
I've read that the assembly line plugs are made for one bank of cylinders or the other and can thus be "single platinum tipped". This saves Ford money.
However, down the road, when the time comes to replace plugs, there's nothing to assure that the premium center electrodes go in the correct bank and the premium prong electrode goes into its correct bank.
It's simpler to make replacement plugs "strong both ways".

Someone in your truck's past simply installed basic plugs. They worked just fine for a while but then the mismatched flow of mighty electrons took their tool.

 

The old ones were exactly the same as the ones i put a year ago and didn’t wear unequally as this, anyway i checked the back pressure of both catalytic converters, did an intake leak test even compression test, they were all good

 

I think i found the problem, not sure about it but it would make sense. I checked all my oxygen sensor and one of the upstream doesn’t work, i read 0.002v on closed loop. I know that oxygen sensor produce their own voltage between 0.250v to 0.750v, but could it be the reason why my truck buck and jerks while accelerating and also let a little pop out the exhaust on idle ? Also found that my throttle cable is loose

 

O2 sensors last 10 years or 100K. You're overdue.

Throttle cables stretch. There's a common fix involving adding a small tie wrap behind the end bead (at the throttle end) to take up cable slack.
Whether that's a fix for you is something you have to determine.
Also I've read that a worn or loosely mounted TPS (Throttle Positioning Sensor) can send out bad / mistaken data to the truck's brain.

 

I replaced the 2 upstream o2 sensors, cleaned my intake including the throttle body and erased the kam memory to get a fresh start. The problem is fixed, now i just have to replace the thermostat housing, find why i have a vibration in the floor ( the suspension, axles and driveshaft are brand new ) and find the leak in my a/c, i suspect the evaporator

 

the problem isn’t gone, i drove it for about 30 min and it started jerking again, but worse than before, i cleaned every ground possible, even the ground plate on the D.I.S, changed the air filter, changed the spark plugs, changed the 2 upstream o2 sensors. When i checked the live data i saw that there is a fault for the kam memory, but no code. Also noticed that it will run fine for about 30 min then start bucking, if you turn it off and back on it will stop for another 30 min.

 

I talked about my problem to a lot of technicians and i got told to check if there was vacuum building up in my fuel tank, watch my fuel pressure while it does the problem to check the fuel pressure regulator and check the D.I.S coils primary and secondary circuits.