Cel Po171

[brkwd51]

I had my check engine light come on 2 days ago. just in the middle on my way to football practice. And it was on all day. But the next morning it didnt come on when i started the car. But then later that day in a middle of a drive it came on again.
So i went to autozone tonight and checked it out. and it is the PO171 which is:

Definition
Fuel trim bank one condition

Explanation
The powertrain control module uses the oxygen sensor to calculate the air/fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine back only.

Probable causes
1. If bank one and two codes set together suspect fuel pressure or MAF
2. O2 senor defective
3. Ignition misfire- repair
4. Fuel injector problem

This is what i thought the problem might be about because i recieved the car july 5th... and i was not aware that the car needs premium fuel so ive have drivin the car about 700 miles since all on regular gas. this afternoon i filled it up with 93. so could it be on just because of the poor gas? or could it be something bigger?

btw. the car is all stock except for a injen CAI. and it has 81k miles

 

[BOOSTR]

Another possibility is the wastegate actuator:

Some customers may experience one or more of the following conditions:
Whistle noise from the engine compartment at idle.
Engine speed is limited by fuel cut condition under high boost conditions.
Check engine light on with P0171 - FUEL TRIM SYSTEM TOO LEAN stored in memory.
The above mentioned conditions may be the result of a ruptured waste gate actuator diaphragm. To determine​

if this is the cause follow the repair procedure as described below.
*************************************************
But before you replace anything, disconnect the negative battery cable, pump the brake pedal a few times and let the car sit for a few minutes to clear the pcm. Reconnect the cable and start. Have your alarm fob ready because it will most likely go off when you reconnect.

Hopefully you've been using premium since discovering that you need it. If you don't know that the previous owner changed the plugs recently with that mileage, pick up a fresh set of NGK stock no 4291 and put them in.

Besides the CEL and regular gas, did the car seem to be running right with a smooth idle and under acceleration?

 

[brkwd51]

yea it ran smooth to me. the idol was a little rough sometimes... but no stalling or anthing of that nature.

 

[magnumP5]

Small vacuum leak more than likely (can also be wastegate actuator). Just go over all pipes and vacuum lines and make sure everything is tight and there are no splits/holes in them. Test your wastegate actuator by removing the vacuum line that goes to it (at the other end and blow into it). If you can feel/hear air escaping then the wastegate actuator is bad.

 

[BOOSTR]

Definetly check and eliminate the little things before you consider replacing the maf/O2/wastegate. You should consider adding a boost gauge so you can monitor your vacuum/boost. Subtle changes in either one are often your first tip to a problem before throwing a cel.

 

[brkwd51]

how do i check the wastegate actuator? do i take it off... and the blow into it? if so what is the best way to take it off?

 

[magnumP5]

You can leave it on. Just follow it's vacuum line back to the source and disconnect it there. Blow into that end (use some force) and feel/listen for escaping air. If there is any air leaking and/or it's not holding pressure the actuator has gone bad. Does this make sense?

 

[brkwd51]

yea it does, thanks! ill go try it out.

 

[brkwd51]

ok so i disconnected the battery so i could reset everything. and the check engine light went away. i drove it around for 2 days... and while im stopped at a stop light it comes on again.
i havent gotten it checked out at autozone yet (because i assume its the same code).

heres something i was thinking about though... my car hesitates horribly... so wouldnt that mean that its running rich and not lean?

and if the problem is with the wastegate actuator, maf, or fuel injector.. is it unsafe to drive? should i drive it differently than normal unitl its fixed or what?

and also what is an ignition misfire -repair? im not sure what an ignition misfire is and why does it say repair next to it on the receipt?

and finally... i want to check my wastegate actuator, but the its hose that connects to some T piece is very difficult to pull off. am i missing something? should i spray it with some wd40 or something? i dont want to force it and break anything...

sorry for all the questions...
im just a noob that is worried about my msp. please help me out.

 

[brkwd51]

bump. anyone with some help??

 

[BOOSTR]

Did you check all of your connections to see if everything was tight and secure?

Disconnect the hose directly at the wastegate and place a tester hose on it.

You need to hook the car up to a vacuum gauge and see what its reading at idle. Anything less than 20 Hg/In and you've got a leak for sure.

As long as the light is steady on you should be okay versus a blinking light.

 

[brkwd51]

ok today when i filled up the car with gas. i turned on the car and the light was off.... soo weird?

 

[magnumP5]

Yep, that's pretty much how this CEL works...

 

[brkwd51]

yea... because i just parked the car in the garage... and right when i put on the ebrake... the light came back on. so yea... issues

 

[jbilliel]

I am in the exact same boat and I have to bring the car through emissions this week!!! Argghh...

Last night I went through all of the connections, checked the vaccuum lines, pulled out the MAF and cleaned it and pulled off the exhaust manifold.

The MAF seems to be working fine as I unplugged it the car ran like crap. I plugged it back in and it ran much better.

The vaccuum lines are in good order.

However tonight I need to test the WGA by blowing into it like mentioned above. I also removed the heatshield and noticed that there is a broken stud and a missing nut. So I put a new nut on this morning, drove it to work but the cel is already pending so that did not resolve the issue.

This weekend I may try to test the o2 sensor on the manifold and clean it out at a minimum.

Anything else I am missing?

I also have a bad miss between 3.5k to 4.5k. I ordered new NGK plugs and wires. They should be here shortly.