Low RPM Knock/Lugging

I’ve had a random low RPM (1500-2000) lugging/Knock since day one of owning my 2016 Auto. I’ve noticed that 93 octane calms this down for a while. I decided to pull my plugs to give them a read around 15k miles. My dad was a Honda tech for 20 years and said that he’s pulled plugs out of cars with 100k+ miles that looked like they were brand new, cleaner than these. Notice the silver speckles I’ve been to the dealership 4 times with the issue, they always give me the unable to duplicate response. I took the tech on a road test, he tired to say I was feeling the road. I’ve been working around cars my whole life, I know when my truck is bucking like a horse over bumps in the road. It’s random and sometimes it’s worse than others. Anyone have any opinions or suggestions?

 

Why oil on the head?

 

Are you referring to the base being black with whatever is burnt up on the plug?

 

I replied back in another thread. But I think a grey/white ground electrode strap indicates a hot or lean condition??

I also have spark knock on 87 octane. They advertise it being able run on regular.

 

Lean condition



but it looks like it has deposits on it too....carbon deposits could mean running too rich so who knows.

 

I'm no expert but on torque my OBD2 scan tool. I hit the gas and it drops from 14:1 to as low as 11:1 air fuel ratio.

 

This is idle.

 

I've been told that monitoring AFRs on a scan tool isn't accurate, you'd need a wideband AFR gauge/sensor to get true readings. But if that is your true reading, that sounds rich for a N/A motor.

 

Okay, so I’m not crazy for saying these don’t look right. I’m past them telling me it’s a “vehicle characteristic”, you can say that about the truck being a slug, but not about the motor knocking on the fuel that’s recommended. I’m really curious how these motors are going to hold up in the long term.

 

My 17 does this as well. I haven’t pulled the plugs yet but IMO yours look normal for a production vehicle. The deposits you are seeing could very well be from moisture in your fuel.

 

I know in another thread there was a guy here who amazingly had already exceeded 100,000 miles on his Gen 3 Taco, I think he said he had been driving around 5000 miles a month. He was apparently good to go, I guess we'll see how everyone else makes out. I'm at 31,000 and I've had no issues with the engine (only the SRS system).

I do get a very subtle, extremely brief knocking/pinging when accelerating sometimes, it'll last less than a second. I was concerned, but it says right in the manual that this is normal and nothing to worry about. However, the OP sounds like something else entirely is happening....

 

Have you replaced your crankshaft position sensor? I probably need to look at my plugs too but I know for a fact my truck couldn’t hit the right AFR for the first few thousand miles and I would have the same experiences you did - running premium would work for awhile but it would degrade. I’d be willing to bet you also experience slightly better gas mileage on premium than regular - which you shouldn’t. That sensor is at the center of so many calculations in this ECU. If you haven’t replaced it do it

 

Had it changed the day the recall became available. Didn’t solve the issue. I asked Corporate Toyota about long term damage from the bad sensor and they said you have a 50k mile warranty. They wouldn’t own up to the possibility that the bad crank sensor could have caused long term damage.

 

Have you tried ethanol free gas? Maybe the ethanol is causing problems?!? Just a thought. My taco ran better on 87 ethanol free gas.

 

Did you replace the plugs? If so, did the issue go away?

I have a lugging feeling near this RPM too and assumed it was just due to the truck shifting to early and being in too high of a gear causing a bucking feeling.

 

Also interested as replacing plugs is a cheap enough thing to do to keep it running optimally... Easy, may be another question though. Replacing plugs is normally super-simple but in reading the service manual it seems 3 of the plugs require a fair amount of disassembly to reach though I haven't attempted myself yet. How easy was it to swap them for anyone who has?

 

34K on mine and NEVER a knock or a ping. Run the 87 stuff. Those plugs don't look right to me.

G.

 

I would be interested in seeing how far the plug actually projects into the combustion chamber. It looks like there are at least 2 full threads of depth past the end of the plug hole. Is this anything... dont know, just an observation.

 

For such low mileage, those plugs look bad - maybe running too rich? Do you do a lot of short trips? I know on most older engines they would run a bit rich until warm up - not sure if that would still be the case tho.

 

My Engine does not knock or ping but i do get that weird low RPM stumble hesitation every so often.