This is a very long story but I’m going to make it short. I have a 2013 Hyundai Santa Fe GLS 3.3L. The Issue started as an oil leak which the mechanic said was a rear main seal. It ended up being an oil pressure switch.
The intake manifold and fuel rails have to be removed to get to the oil pressure switch. The oil leak has been fixed. While doing the repair, the PCV valve was replaced, the spark plugs, the intake manifold gaskets and the throttle gasket.
Was advised car was fixed but the mechanic believed it had bad gas in it. When driving my car home, it didn’t feel right. I had to drive the car home about 30 miles from the mechanic. While driving it felt like at times it was losing power and would shake. Feels like a fish biting on a line About a mile from my house the check engine light started flashing. Got the car parked and a friend came over with a code reader These are the codes that were showing, a P0300, P0172, P0301, P0303, and P0305.
I took the car to another mechanic, he looked at the car and said he did not believe that is was misfiring that I have a vacuum leak. He said he drove the car and could not get it to throw any codes but felt the jerking in the engine I was describing. He doesn’t have a smoke machine so he can’t confirm vacuum leak. So I picked the car up and brought it home.
This is what I’m noticing. The engine idles high when cold and slowly drops down. If the engine is cold and you put it in gear RPMS drop. At start up a hear a strange sound but really don’t know how to describe it. Starts about 20 seconds after the engine is started and last for about 30 to 45 seconds. It’s not a loud sound. If the car is misfiring while the engine is cold I cannot feel it. However, once the engine warms up and the car is driven you can feel is misfiring. It feels like it is only doing in above 20mph or when accelerating. If driving under 20mph I can’t feel it misfiring.
The engine just doesn’t feel right nor sound right to me. Sounds like it runs louder to me.
Does anyone have any suggestions before I take it to another mechanic? Any ideas on what is wrong? I could really use some advice and direction on this.
P0172 System Too Rich (Bank 1)
You kind of missed an opportunity when your friend retrieved the codes for you.
The "code reader" does much more than just read codes.
It's a scanner. Even the cheap ones allow you to look at Freeze Frame Data.
It's a "snapshot" of data from a number of sensors and components at the time when a code is thrown.
So in your case with those Bank 1 misfires and the P0172 code it would have been useful to look at a few things.
(you still can if your friend didn't clear the codes).
"Bank 1??", you ask. You have a 6 cylinder engine. There are three cylinders on Bank 1 and three cylinders on Bank 2.
On your Santa Fe the setup looks like this:
If you look, you can see that those P0301, P0303, and P0305 misfire codes (the last number refers to the cylinder number) are all occurring on that same cylinder bank. It's called "Bank 1" because the #1 cylinder is on that cylinder bank.) (P0300 just means "multiple misfires).
Looking at the Freeze Frame Data the 1st thing you'd want to look at is what the fuel trims on Bank 1 were doing at the time the P0172 code was triggered.
I suspect they were in the high Negative numbers for that code to be thrown. Something like minus 20% or above on LTFT (Long Term Fuel Trim) Bank 1, and another high minus number (probably not as high) on STFT Bank 1. So you'd just want to look at those to confirm that's what's happening here.
(watch a few youtubes on O2 sensors and fuel trims. In 30 minutes this will all make sense to you)
But you can't ignore looking at the same fuel trims on Bank 2. Why? Because the fuel trims have to reach a certain percentage to throw a code. You want to be sure that you don't have high negative fuel trims on Bank 2 that are just below the threshold to throw a code on that bank also.
That's unlikely, because all of your misfires are on Bank 1 but you'd want to check to confirm.
That's important because if this is just limited to Bank 1 you can eliminate a lot of possibilities.
Stuff like IAT and ECT sensors. MAF and MAP sensors. Fuel pressure regulator, PVC valve, EGR valve. These things would affect BOTH cylinder banks, not just one.
So what if the issue is just limited to Bank 1? Why would that be happening?
The 2 most likely reasons (not in order of probability):
1) A malfunctioning upstream O2 sensor on Bank 1 that's "stuck rich". But this would be easy to determine because the downstream O2 sensor would "tattletale" on it.
You can't have a "lying" upstream O2 sensor saying the fuel mixture is "rich" when it isn't, and have a downstream O2 sensor agreeing with it. The lying upstream sensor voltage will show "rich" and the downstream O2 sensor voltage will show lean. Even a half-ass mechanic should be able to see that
2) A fuel injector that's "leaking" on Bank 1.
Why would that be happening?
A faulty fuel injector.
But we have to also consider that you just had work done where they had to unplug the injectors and move that wiring harness out of their way.
A short on one of the injector ground signal wires to ground on one of those Bank 1 fuel injectors would cause the fuel injector to be stuck open.
The computer would "trim back" the fuel on Bank 1 causing a "lean" misfire on the other 2 cylinders while not being able to compensate for the "rich" condition on the one with the "leaking" fuel injector.
Sorry Ashley, you tried to keep your question short and I rambled on and on.
Watch those videos I suggested and then consider the #1 and #2 reasons in my reply.
This is just for the guys following along who may be interested what a lying upstream O2 sensor that's "stuck rich" looks like compared to the downstream O2 sensor "tattletaling" on it.
So here is a "lying" upstream O2 sensor. The voltage never drops below 500mV.
It's malfunctioning. It's "stuck rich"
It's telling the computer to go into negative fuel trims and so the computer does it.
Probably until a P0172 code is finally triggered because no matter what the computer does it can't make the "stuck rich" upstream O2 sensor happy.
Now look at how the downstream O2 sensor is "tattletaling" on the upstream O2 sensor
Look at the voltage. It's at 20mV. It should be around 450 mV. It's showing too much O2.
You can't have an upstream O2 sensor measuring too rich with a downstream O2 sensor measuring too lean.
It's a dead giveaway.
... and that's all I have to say about that
Thank you. It’s been a nightmare of an ordeal. Unfortunately the codes were erased. I feel that it’s a bad fuel injector.
almost certainly an intake leak
The misfires are all on one side of the engine. (cyl 1, 3, 5)
You have p0172 because the computer is trying to add more fuel to compensate for the vacuum leaks, and making the mixture too rich in the other bank as a result.
Sounds like the first mechanic was a bit of a disaster.
Hi Ashley I would just like to know if you ever sorted the issue out? I am experiencing the exact same issue and would like to know if it was in fact your injectors or if it was your O2 sensor?
I don't think Ashley will be back, Daniel. You should probably post a new question , including all your vehicle details so we can help you better.
See the "Read This First" topic.