Running Rich

[chewy012]

Update: while I still haven't gotten a rich mix code yet, still getting a stall out after and hour plus on the high way. Didn't hook up the scanner so not sure what the IAT read but, yeah died a block from home. Had to let it sit for a few hours.

Other than that, in the morning she ran like a raped ape

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[chewy012]

Ok, so I did in fact speak too soon. Check engine light comes on in the morning almost exactly once I hit 60mph on my way to work. Stays on the whole way, unless I let off the gas (in gear) for a few seconds, then when I get back on it, light comes back on. Coming home from work when it's warmer, It does come on.

So my though was the bi-metallic was goin bad, but I tested it and it seems to be operational.

I'm almost, ALMOST stumped.

Any other thoughts on what's causing my rich burn?

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[RonD]

I would get the code(s) at this point and see what problem might be.
Could be Lean code, fuel pressure dropping at higher demand

 

[chewy012]

Code just says o2 rich mixture. Off the top of my head I can't remember the number, 522 maybe? Just can't figure out what is causing the truck to run rich :/

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[chewy012]

Not 522, my bad. I'll pull the codes again maybe tomorrow or Monday cause I just had the battery disconnected. But yeah from the scanner if I remember right, it's fairly vague, just says like HO2S rich mixture bank 1.... there's only one sensor on this guy though after the Y before the cat.

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[RonD]

O2 Rich code means O2 sensor voltage is high, above 0.7 volts, from low oxygen content in exhaust, and so the computer has lowered the fuel injectors open time, shorter pulse width, to inject less fuel to try and bring down O2 sensor voltage to 0.45 volt range, sweet spot for a good burn, not too much oxygen and not too little oxygen

The computer has built in Pulse Width ranges, not limits, ranges.
When it gets to a low or high range marker and stays below or above that mark for a set time, then computer sets a code and turns on CEL to notify the Driver of the problem.

Yes, exact code numbers are important because computer is not smart, a code never means engine is running rich or running lean, it means computer is getting numbers outside of a range it has in preset memory, so it sets a specific code because of that number.
English translation of a computer code number leaves alot to be desired, lol.

 

[chewy012]

So while I can't get the CEL to show it's face this after noon (I'm as soon as I hit the highway tomorrow morning it will), I'm sitting here with the truck at op temp, MAF unplugged. No CEL and o2 is reading .96V.

While I'm sure the o2 reading is directly because the MAF is not plugged in, I would expect no MAF signal to throw a CEL?

curious.

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[chewy012]

Do you know what pulse width at idle should be? I'm at 1.4-1.5 at idle with no A/C

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[chewy012]

Code is 173 memory. Scanner says HO2S system rich. internet says Oxygen sensor not switching.

Is it the O2 sensor? It's only a year old :/

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[RonD]

No, never looked at specific pulse width times for specific engines and fuel pressures.


"O2 not switching" means the computer is changing pulse width time but O2 voltage is still showing .9 or .1, so it could be O2 sensor but most likely there is a mechanical Rich or Lean condition that computer can't compensate for.
For Lean that usually means a larger vacuum leak, for Rich ?? ....unmetered fuel is getting in to intake maybe.

I didn't reread this thread, so I will ask if the engine is really running Rich, smoke out the exhaust?
Spark plugs are a darker color?
MPG in the toilet?

MAF sensor is a main sensor, that should set a code in under a minute of start up, so maybe computer issue???

 

[chewy012]

No smoke from the tail, but noticeable mpg drop, 3-5 mpg.

Haven't pulled the plugs, but I check my mileage every tank. This morning the light came on, all the way down the highway. Stopped for gatorade, no light after that (engine off, warm restart).

Seems to be having an issue going from warm up mode to warmed up and running mode. Like it's not recognizing that it's warmed up. Cause when i start it in the afternoon when it's hot out, no CEL.

Hmmm

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