Multiple Codes

When driving, the truck sputters/hesitates when I accelerate after shifting gears. Pulled codes and these came up: P0171, P0300, P0430.

The P0171 has come up before without the other codes. It ran fine. Even my gas mileage improved. Mechanic checked for vacuum leaks, and found nothing.

I've had the P0430 before, and replaced the O2 sensor. So that will be done.

The P0300 (random/multi misfires) is new to me. I've been researching for over an hour, and getting more confused on what it can possibly be. This is the one that I am really worried about as my truck has never ran like this, and this is the first time I've gotten this code.

I am in Salt Lake City on a road trip vacation from Florida. There were no issues at all until this morning. I need to get home next week. Being at my brother-in-law's helps as I can work on the truck. But I do not know where to start. I don't want to just start throwing parts at it, and I also don't have tons of $$ or time.

Any help/advice/suggestions would be greatly appreciated.

 

P0340 is a failure of a catalytic converter, not a sensor. The P0171 and P0300 may be related.

Bank 1 is running lean beyond threshold and you need to figure out why. A dirty MAF can cause lean but it would likely cause lean on both banks. I would still clean it first. Plus its free.

Next I would check vacuum hoses, the ducting from the air filter to the throttle etc.. listen for hissing while its running. It may only happen when cold or hot.

After this I would need to check misfire counts, possible injector failure on bank 1 can cause lean and poor driveability.

 

@Bishop84 Thanks for the reply. Will a vacuum leak also cause the P0300 misfire code?

 

Yes, depending on the severity, p0300 is random misfire and is usually a difficult code to isolate.

 

I keep reading about changing the coils and/or the injectors. Would doing that be a good place to start?

 

Just advising with my experience.

The coils on the 3.4 are shared bank 1 to bank 2, meaning if one coil failed you would likely have an issue on both sides. Also coil misfires typically don't cause lean and would cause its own specific cylinder misfire code.

The injectors however are cylinder and bank specific and are known for failing on the 5vz, that said are hard to diagnose without an oscilloscope. You can use a stethoscope but it's hard to gauge failure based on sound.

A plugged fuel filter can cause lean, but again, it would likely cause lean on both sides, and is unlikely on these trucks.

 

Sorry...I have the 2.7L.

 

You don't have p0430 then, 430 means bank 2 catalytic converter, you'd have p0420.

This changes a lot haha, I would definitely start by cleaning the air flow meter.

 

Thanks man for your help. I will definitely check that.

 

I've had the P0300 caused by a lean misfire from a bad O2 sensor. But I agree start by cleaning the maf and checking for vacuum leaks.

 

P0171 system too lean, how many miles on your truck?
look for loose vacuum hose. if your truck is high mileage, 140k mi.
I would clean out the air flow sensor. with brake cleaner or electrical contact cleaner. then clear codes and test drive to see if same code pops back up. if code P0171 doesn't come on. near future may need to replace air flow meter.

 

I disagree on the brake cleaner. Go to local auto parts store for MAF specific cleaner (or electrical contact cleaner, last resort). It should only be about 6 bucks. If you have an oiled air filter I bet that will fix the problem. Those things are fragile/finicky. If problem continues I'd disconnect battery, swap coils, reconnect battery and run for a bit and recheck codes. Very easy/fast way to narrow the problem(s) down.

 

Thanks guys for the replies. Much appreciated.

I ran the scanner again. When I did it yesterday, I was in a rush and only remembered/noticed the 3 mentioned above. So, this morning, I saw that I have the P0302 code for cylinder #2.

The MAFS looks clean. I've cleaned it a few times before hoping it was the cause for the P0171 code. Maybe it's just time to get a new one. How do I check to see if it is working or not?

Info on my truck:
2001
2.7L
282K miles
Original MAFS, coils, injectors

 

Code 302 try swapping coils

 

take some pliers and squeeze the vacuum line to the brake booster and see if there is an improvement in idle. You just might have to follow every line that comes off of the intake, vacuum lines, air inlet AFTER the MAF sensor, and if easily removable examine it, there just isnt any quick and easy answer.

damn, truck broke on vacation, sorry

 

Yeah. I swapped it with #1, and the code popped up for cylinder 1. So I'll be getting a new coil. Thanks!

Yeah, the truck breaking down on vacation does suck. We haven't even reached our furthest destination (California). Fortunately, I am staying at my brother-in-law's house right now. And we get along very well, so running around getting parts and working on it in his driveway is not a problem. What also sucks is not making it to Cali to visit my family. This little hiccup will have us heading back home instead. I just want to get back home to make sure everything is okay. Going further doesn't seem like the best thing to do.

The P0171 code hasn't popped back up. But I will give that a try as well. Thanks.

 

If you get it squared up so it runs well and codes stay cleared, I'd proceed to see family. There's no more risk going one direction than the other.

Hope you get it worked out!

 

Thanks!

Yeah. I've thought about that. This trip is pretty easy going. Nothing really set in stone except for certain destinations and being back home by the 6th. Whatever pops up in between those destinations and dates becomes part of the trip. Now, it all depends on making sure the truck runs well before hitting the road, no matter what direction. I am not in the mood to be broken down in the middle of the desert, with no significant city/town close by. Hopefully it doesn't take to much time to figure it all out.

I hate a bunch of small issues that need to be chased. Sometimes one big issue is easier to deal with.

 

Plenty of TW members between here and there. Drive hard.