Hi, I recently bought a 09 ford ranger 4.0L, with the transmission (reverse and drive) out of it and several other small things wrong. I limped it home and it ran great as far as the engine goes with no stalling issues. I pulled the transmission out and had it rebuilt, and in the mean time fixed all of the other mechanical and rust issues. I test drove it today and it is stalling once you accelerate over 2000 rpms while in drive, but will rev until it hits the rev limiter(3000rpms) while in park and neutral. The check engine light is on, and I am probably going to have to buy a code reader since I can't get it to a parts store to get it read. I tried draining the computers capacitors to reset it while it was still on the rack and it seemed to fix it, but apparently it didn't. Any advice would be appreciated, thanks.

 

Welcome to the forum

If you have a smartphone then get a Bluetooth OBD2 reader with extension cable, under $40, it uses free or $5 APPs and your phone as the display
It can of course read codes, but you can also watch Live Data as you drive

As for current stalling issue, so it doesn't stall when you shift into drive or reverse, but does run out of power and stall in Drive when at 20MPH, 30MPH, 40MPH???

That reads like one of two things
Fuel flow, filter or pump
Or
Partially Clogged exhaust

Try holding RPMs in Park at say 2,500 for a minute or so and see if there is any issues


The DTR(digital transmission range) sensor on the shift linkage is important, did it get plugged back in and set to Neutral?

 

Thanks for the advice, I did buy a code reader tonight and a couple codes popped up (P0102, P0172,P0175, and P0446.) Based off of the codes I am thinking it's the mass air flow sensor, I've heard of people having trouble with them before on rangers. The truck does have a k and n filter on it that the previous owner put on it, which may be contributing to the problem. The mounting bracket for this filter was cracked around the base (may have been sucking air) and was running fine when I got the truck. I did hold it at 2500rpms while in park and had no problems so it's not fuel. The truck just shuts the engine off at 2000rpm when in drive, overdrive, drive 1 and 2.

 

Yes, clean MAF sensor and check connector

Computer has these code for MAF sensor voltage
P0101 Mass or Volume Air Flow Circuit Range/Performance Problem
P0102 Mass or Volume Air Flow Circuit Low Input
P0103 Mass or Volume Air Flow Circuit High Input
P0104 Mass or Volume Air Flow Circuit Intermittent

It would tend to set 101 or 104 if the sensor itself was bad

Computer "knows" it is running a 4 LITER engine, so it knows EXACTLY how much air will be coming in at any RPM and throttle position, its just math
What MAF sensor is for is to tell computer the WEIGHT of the incoming air, there is also an air temp sensor(IAT) for the same reason
So the code means MAF is sending lower voltage that it should be, unless you are running the engine at 20,000ft elevation, lol, very light air that high up

Yes, could be the K&N filter, pull it off it can limit air flow which would cause lower voltage than expected at higher RPMs