Need some technical help on my truck.

mrrsm

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Oct 22, 2015
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Tampa Bay Area
Nope... BUT... Possibly a "T*ts-Up* O2 Sensor Heater...

Watch "Crazy Ivan" The Man from PHAD" (Pine Hollow Auto Diagnostics) from around 4:40 along into THIS Video:

 
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TollKeeper

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Dec 3, 2011
8,027
Brighton, CO
I am thinking it might be wiring.. But I will have to find a good diagnostician for that. I hate wiring!

That being said, the truck greeted us with more codes Friday night...

The same P0131
Plus, P0446 and P0305

I shut the truck off, as I was working on the XUV. Pulled the truck back in the garage after working on the XUV, and the misfire was GONE! I checked the coil, the wire, and the plug, no issues.

wtf???

So I pulled out my code reader, got the codes, ran the graph, and cleared them. I am hoping it was just a glitch, or something. Graph showed no issues for all 3 codes. I am thinking a low voltage, or maybe some circuit didnt get the wake up call from the LAN.

The wife had been driving it around for a long while, with no mis-fire, and then I go to move it 20 feet, and the check engine light is flashing within 10 feet, and its gone one engine start and 20 feet later.

If it is the P0446, at least thats the cheap and easy one to replace, on top of the engine, 2 hoses, one wire harness, 1 bolt.

But I am going to wait for the MIL to populate again with that code.
 

Sparky

Member
Dec 4, 2011
12,927
Not sure where the O2 gets its reference voltage from but I'd be tempted to try running a temporary power wire to it and see if it stays ok. If so, you've got yourself a bad wire somplace.

....And then, knowing me, I'd leave the "temporary" in place until I could get back to solving it, and it would stay "temporary" for the next 3 years...
 
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TollKeeper

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Dec 3, 2011
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Brighton, CO
So I worked on the Aztek again on Saturday, its been sitting on a battery tender for the last 2 months.

It has a misfire on Cylinder 5, with a code P0305, as well as the O2 sensor.

I already replaced the plugs and wires on it over the winter, and I did verify they are still good.

Rented a fuel pressure test kit from Autozone. What a pain in the ass that is on the Aztek...

But anyways, it primes to 56psi, and slowly drops down to 42psi, and holds there. Which is perfectly normal. I cant do a running PSI check because of the way the system is designed.

Seeing the PSI is good during KOEO, I put it back together under the hood, and went ahead and replaced the Fuel Filter. This greatly improved its drivability, BUT... It still has a miss during high RPM's, with a flashing check engine light, and a O2 sensor issue.

Tonight, I am going to drive it again, get the MIL light to turn back on again, and stay on. Then I will be dropping it off at a shop local to me. See what they can dig up on it.
 

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