Hey guys, hoping for a little troubleshooting help. Help me solve the problem and I'll order you a case of your favorite beer.

I picked up a 2002 2500 for dirt cheap and have been working through issues. The motor is the 5.0 and it has about 180k on it. PO had a shade tree mechanic install a distributor. It was 180 off, so he could never get it starting. I have it starting and running now, but it runs like dog water. It also had a stolen cat on bank 2 that the PO had replaced. I'll add some notes about what's been done at the end.

I've started by clearing the codes to get a timeline of how things come up.

It starts up immediately. Fuel pressure sits right about 65 and tapers at acceleration. If I let it idle, it stays okay for a while, but then will commonly throw a P0101. Once it's warm, it struggles if I give it gas. If I let off of the gas, it usually dies. Then it won't start again unless I keep the throttle down and gradually let go over the course of a few minutes. The stft shows it as running rich during this time, when cold it was mildly lean. It has some fuel system cleaner in it, but that's been about 25 gallons ago and should be burned out.

I mentioned a P0155 in the list. I didn't have another sensor on me and the part store was closed for the weekend, so I swapped the bank sensor 1s and the code came back up to the same side, not following the sensor.

Since I've owned it ( a few months ) I've replaced the plugs, wires, coil, distributor ( I think he actually just cleaned the old one and I had plenty of credit at the local part store. ), fuel filter, maf, and iac valve,

Any ideas for troubleshooting or data I can provide to help troubleshoot? I am technically capable and have tons of tools ( hobby machinist ) albeit my code reader isn't the greatest and doesn't show individual cylinder misfire counts.

 

watch the MAF reading as the engine warms up

 

Any specific maf reading to look out for? I have two mafs, the old one and a brand new one, and see it on both. Happy to try and isolate it more though.

 

Nope.

The P0101 code indicates the computer received unexpected MAF values. (https://www.obd-codes.com/p0101)

Logically, we should first check: what are they?
Then go from there.

 

Just closing the loop here. I replaced the fuel pump and all of the errors went away. It's running like a champ now. It doesn't want to immediately start up after shutting down sometimes without giving it a bit of throttle, fuel pressure stays at 65+-. So, I'll check that out next.