Road trip went great. At 65 MPH going down I-44 in Missouri from St. Louis to Joplin, I averaged 17.5 MPG with the 5.4L and 3.73 rear axle. Not too bad in my opinion since all I've done is new plugs, boots, wires, and fuel injectors. Have not yet touched the coils. Anyhow, trip went smooth until the way back home. I stopped at a "left-lane exit" rest area that was located between the highway. Upon exiting, the problem is that trying to merge back onto the highway puts you in the passing lane - so I needed to accelerate pretty hard to get up to cruising speed. After accelerating (I probably hit 5K rpm), I had a Check Engine light come on. Vehicle drove fine all the way home (another 100 miles) with no shudders or hitches, etc. After stopping three more times (all times turning the motor off), the light went away and it has not been back.

So, my question is, is there anything that I should check out? Obviously without the code to check there is little I can do, and with no obvious engine problems, I wonder if its an O2 sensor or something. Any ideas of things to inspect or do I need to wait for it to come back on?

 

About the only thing you can do is hook up a code reader and repeat what you did to make the light come on. Once the light is on, scan for codes without turning the engine off. Anything you do without first getting this code is pure guesswork.

 

Welcome to the rest area near Stanton! I drive by there frequently and that sucker is located in a nasty valley.

The PCM will store the fault code for either 40 or 80 drive cycles (unless reset) and you do NOT have to have the CEL on in order for a fault to be read (by a decent scanner).

Check your local AutoZone or Advanced Auto parts to see if their scanner can pull the stored code(s).

Chances are, its just transitory due the particular harsh condition under which you noticed it setting and it won't come back under normal conditions. Getting it read, though, will allow you to form a history in case the CEL comes back. My guess is that it's probably an O2 code that was due to the exteded harsh acceleration condition.

 

Had the code ran --- P0153

Edit: P0153 02 Sensor Circuit Slow Response (Bank 2 Sensor 1)

So this is the PASSENGER side, number 1. Where is the 02 sensor located at? This is between the engine and catalytic converter?

 

Bank 2 is the driver's side. Bank 1 is always the side with the #1 cylinder. In your case, the #1 cylinder is on the passenger side, making that side bank 1.

The sensor you want is the driver's side, upstream (between the engine and catalytic converter.)

 

Ahh, thank you. That makes sense. I did some searching here on the forums and read another thread that was wrong. Thanks Alloro. Appreciate it.

 

I'd just clear it and let it run for a while and see if it comes back.. The exception is if you have an upcoming emissions test in the next month or so.

 

I went ahead and bought the O2 sensor. For $36 I'm going to have peace of mind. I'm one of those people that when I know something is not right, it bugs me. Plus, that's the sensor that its easier to change out as I can reach it from the wheel well.

Anyhow, you are more than likely correct. I could probably drive this for a long time before have issues, but here in IL they love their emissions testing and the last thing I need is another hassle with the state because a code appeared.

 

If your luck with this stuff is like mine, the CEL will come on as you're waiting in the emissions testing line. LOL