So i picked up a 99 3.0 a few months back to be my work vehicle. I just recently came upon a problem with it that i'm working my way through. When driving I notice the car bogs down and sputters while driving at higher speeds and it does it sometimes while at a stop. I ran codes on the truck and did some work on it. I replaced the EGR sensor, new plugs and wires, and i had an issue with the bank 1 upstream sensor, so i replaced that too. Today i hopped in the truck and while driving the CEL came back on. This time showing that i was running lean again, my bank 2 upstream was having issues, and i was having a misfire in cylinder 1 again.

All of these together make me wonder if i just need to replace my cat, since bank 2 wouldn't cause an issue with cylinder 1 to my knowledge. I also wonder if i just need to replace my driver side o2 upstream and maybe my ignition coil and cylinder 1 fuel injector, or maybe i have an issue with the crankshaft synchronizer.

lists of codes that just popped up for reference (scanned it with my bluetooth sensor while typing this)

p0301
p1150
p0174

Any thoughts or advice would be greatly appreciated.

 

Welcome to the forum


P0301 is misfire on cylinder 1
P1150 is Bank 2 O2 sensor isn't switching as computer changes air/fuel mix
P0174 is Bank 1 O2 sensor shows Lean even after extra fuel is added

OK, first things first, O2 sensors should be replaced every 150,000 miles, they will pay for themselves over the next 150k miles in MPG.

When you have a V6 or V8 engine then you will have two upstream O2 sensors, Bank 1 and Bank 2
If you get a Lean or Rich code on BOTH O2 sensors then you can be sure the O2 sensors are NOT the problem, to long of odds for that to happen.

O2 sensors read Oxygen Levels in the exhaust not fuel, too much oxygen is lean, too little is rich.
If you have a misfire than means no oxygen was burned in that cylinder, so............O2 sees a misfire as lean, because all that unburned oxygen is dumped into the exhaust on that bank.

So P0301 and P0174 kind of go together

But you also have a Bank 2 O2 code, both banks effected.
So you need something that can effect both banks.
Most common issue is a Vacuum leak.
Simple to tell if there is a vacuum leak, after engine is warmed up and idling, unplug wires on the IAC Valve, idle should drop to 500rpm or engine may even stall, either is good, it means no vacuum leaks.
If idle stays at 700 or higher then there is a leak.

Clean MAF(mass air flow) sensor, always, when there are any O2 codes.
Computer bases starting air/fuel mix on MAF data, if this data is off then mix is off and O2 sensors report that after the mix is burned, computer can't "test" MAF so it just reports O2 sensor codes.
Check air tube from MAF sensor to intake, any cracks or air leaks in that tube means "unreported air" is by passing MAF sensor so computer is getting wrong info on the amount of air coming in, it isn't adding enough fuel so...........lean mix, same as vacuum leak

Other side of why you may get a lean code is Fuel Pressure, could also cause lack of power at highway speeds.
Computer expects 65psi of fuel pressure with a '99 3.0l, computer has no fuel pressure sensor so it just expects it to be 65psi.
If pressure was 35psi then when computer opens an injector less fuel flows in "than expected", so lean mix, O2 reports that, computer sets lean code.
Change fuel filter every 5 years or so.
You can rent a fuel pressure gauge, and there is a schrader valve(looks like tires air valve) on the engines fuel rail so you can test pressure


Check #1 spark plug, see what it tells you about cylinder conditions.
To check if injector is working unplug 4 wire connector on coil pack, so no spark
Crank engine a couple of times
Pull out #1 spark plug and #2 plug, they should both be equally wet with fuel


Fuel injectors get dirty, but easy to clean, SeaFoam or similar injector cleaner can be added to the gas tank, I do it once a year, smooths out idle quite a bit on my '94 4.0l, should probably do it more often but I am cheap


Hard to say about the cat converter, if it wasn't working then you would get a code saying Bank 1 Sensor 2 problem, thats the O2 behind the Cat that monitors oxygen levels, after Cat "cleans" exhaust, there should be higher oxygen levels
If Cat was clogged it would limit power at higher speeds but not lower speeds, you can test exhaust system blockage with a vacuum gauge.

CKP(crank position) sensor problems are rare and never intermittent, that causes no start issue.

Coil pack is a long shot but not a no shot, reverse #1 and #5 spark plug wires on the coil pack, they both fire at the same time with Ford's Waste Spark system.
If you start getting P0305 then yes coil pack is the problem
If it stays at P0301 then problem is cylinder specific: spark plug, injector, compression, local vacuum leak(lower intake next to #1)

 

Thanks for the solid advice. When I changed the plugs and wires a few months ago, I also changed out the fuel filter and cleaned the maf sensor with mafs cleaner. I don't have any leaks leading from there thankfully. Im at school right now, but plan on trying the other tips when I get a chance later today. Not sure how helpful this info might be, but at idle my truck is sitting at a vacuum of roughly 18.4 in/mg. (I'm at my car in between classes, figured I check that)

 

17"-21" of vacuum is expected at sea level to 2,000ft elevation from a gasoline engine.

A large vacuum leak would of course effect that but not a smaller one.

Good read here on what you can test with vacuum gauge: Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine
One of my favorite diagnostic tools

No matter how much they change the spark and fuel systems, a gas engine is still just a self powered air pump, so vacuum can tell you alot.