2011 Running a little rich

Hey guys, my 2011 taco is running a little rich. I know these engines run rich by default but I've noticed a definite difference in the smell when I start it up.

Yes I'm basing this off of the smell as I've been smelling this truck for the last six plus years. I can hook up my ODB scanner and run torque if that helps.

I recently did all my 100k maintenance but the smell continued. I cleaned my air filter, the MAF, changed my spark plugs, lubed everything, front n rear diff, transfer case, etc.

I'm not throwing any codes but I'm wondering if maybe the O2 sensor is going bad.

Thoughts?

 

MPG's are a good indicator of this... Have MPGs significantly dropped?

 

Not any worse than usual . Bigger tires, new suspension, steel bumper.

They've maybe dropped a little, lately.

 

if you can monitor your ECU, check the 02 sensor signal and fuel trims. Do you smell gas or just not what you used to smell? A bad cat can result in some smelly exhaust, especially when cold, but not a smell of raw gas. is the inside of your tailpipe greasy/oily after its cooled off completely?

 

Yeah it's not necessarily a gas smell. It's just a very strong overly powerful exhaust smell that I'm not used to smelling. I will check my O2 and a few other things you just mentioned tonight. I will also check the exhaust pipe after it's cold to see if some of that residue stays behind...

I know I went camping a few weekends ago and my truck was tilted to the driver side and after running the engine for a few minutes I could see that kind of moisture build up in the exhaust pipe... I swipe my finger on it and got covered in a grimy black oily residue That stained my hand.

I'll check the exhaust pipe tonight

 

Have you noticed it more when the weather is cold or cooler?
Mine has a “rich” smell for a few minutes on cold morning.
Doesn’t smell after the engine gets warm.

If you have a scanner, look at the fuel trims.
This could give you and idea.

 

Well it's been 110+ in Vegas and I still smell it, so no. It was doing this back in March and it's still doing it now. I figured the new spark plugs & MAF would help, but nope.

Before I drive it today I'm going to check the exhaust for any oily residue and then plug in my ODB scanner when I get home p

 

Ok @GrundleJuice the pipe was pretty clean from cold, and even after driving 15 minutes home.. no oily residue or anything..

I don't have a CEL but I do see a few issues with a quick ODB2 around the neighborhood. I might need to drive further but it looks like I did get one O2 sensor error and one EVAP system error. Hm. Is there something specific in Torque I should add or look for with the scanner?

 

If it's not oily or greasy feeling then it's probably not severely rich, though it may still be outside of the target the ECU is trying to hit.

 

And actually.. my MPG do seem down quite a bit. although it's hard to tell when I'm blasting my AC full blast in 108° heat.

Here are more fuel guage screenies. First one is idle second one is while going about 30 or 40 mph

 

That's reported afr from the ECU/O2 sensors? Idle should be stoich, and low load cruise should be similar. Def not anywhere near 9 &10:1. That's WOT under boost kind of AFR. If the O2s are bad, they could be sending garbage signal. What are the fuel trims?

 

Um... Those are added to the Torque app using a typical $20 ODB2 scanner. I'm not entirely sure where that AFR report is coming from. I'll take a screenshot of the gauge I added so you have a better idea

I don't think I can add fuel trim gauges to torque but I can see them with the real-time stats. Do you know? I'll try that now

 

No, I am unfamiliar with the torque app. If the OBD2 scanner and/or software doesn't have the Toyota proprietary code it may not be able to read many of the data channels besides the standardized OBD stuff.

Have you looked for others not having any known or suspected issues to see if they have similar reported AFR values? I have an OBD2>USB cable somewhere but only software for Subaru/Denso ECUs. Wish there was some opensource data logging software for these trucks.

 

It looks like I should be able to get live data with this scanner... so I'll check the live data. and there is a Toyota Tacoma profile the app adds when it connects. Idk. Haha

 

I’m no expert, but I’ll agree those AFR numbers look rich.
Was the truck fully warm when you took those numbers?

If you can find the Short/Long term fuel trims that would help some.

 

There is no way for AFr(measured) to be below 11.83ish:1 The stock O2 sensors will not read below that. so those numbers are off (probably the torque app not setup proper and set to E85 stoich)

 

What do the stock sensors do? Reach a max and stop reporting anything outside of the range? The narrow band sensors I have experience with would read as rich or lean as needed, but would be inaccurate outside of a narrow window near stoich. Wouldn't be something I would try to hit an AFR target with but it would give you a rich/lean indication with a number.

 

Stock sensors are not a full wideband, they can read from something like .813-1.23 lambda (11.8-17.9:1 afr).

 

I noticed the 17.9 today when I started briefly monitoring my AFR on my scangauge and doing engine braking. I was wondering why it didn't go higher, but now I know. I think my 08 Z read 24 when I ran the gauge in there.
Monitoring my AFRs showed my truck very near stoich idling and cruising, regardless if warmed up or not.

 

How does the reported engine cold air intake / engine temperature compare to ambient?