Engine stutter/shakes issue? It's driving me crazy

Hi guys, I have a 2015 V6 Tacoma with 50K miles. I've recently experienced the engine sometimes has like a brief (milliseconds) stutter or shakes every 10 seconds or so. It's not at a fixed interval but all random shakes. It's especially noticeable when I'm accelerating. There's no engine light.

I'm not sure if this is coincident but I've recently replaced all spark plugs 2 weeks ago. I've gone back and check to make sure all the coil connectors on the coil are snug and tight. I'm not sure if it is the coil or fuel injector issue and want to get a second opinion before I go down that road. Is is a common issue and if so what should I be looking at replacing?

Thanks,
Steve

 

You need to do further analysis before pulling the trigger on the parts cannon; buy/borrow/rent a scan tool which will allow you to view live data, and verify the information for the plugs and injectors as well as any pending codes. Did you ensure that all the connections were clean and apply a little di-electric grease? Your description makes me think fuel more than spark. What's the mileage on the truck?

 

The truck has 50K miles. I do have one of those OBD reader but pulled no code. I do have access to live data but I'm not sure what I should be looking at. Cleaning and make sure the contacts on the coil connector was what I did the second time around.

You mentioned fuel, is that a common issue for this model/year? Possible fuel pump issue?

 

Just curious why you installed new plugs at 50K. Was something going on you thought that would fix.

 

The plugs are scheduled for replacement at 35/40K i believe. These are not iridium plugs. They're copper plugs. You can see from the picture below that there are consider wear on the tip at angle and the wide gap on the old one.

 

I thought it was at 60K.

 

It's actually every 30K miles. Look up your maintenance schedule.

 

I have no idea what, if any fuel issues are common to your year, sorry - just speculating that IMO, the symptoms seem more fuel (or possibly air) related than electrical. If you can view live data for the coils and injectors, than all you really need to look for is an anomaly; if something is different when the symptoms are present, that's your starting point, so if the waveforms for all six injectors are even and similar without the symptoms, and one (or more) of them change when the symptoms appear, that's your starting point. It doesn't mean that it's a bad injector, but you need a place to start, and that's one of the ways I would use to find that starting point.

 

How was the truck running before you changed the plugs? The way I am reading this it seems that there were no issues before you changed the plugs.

 

It was fine before. So I'm not sure if it was a coincident or bad plugs.. bad coils?

 

Lets see.


1.) Truck was running fine.

2.) Changed the spark plugs.

3.) Now it doesn't run fine.

Logical Deduction: One or more of your spark plugs are screwed up or something got screwed up during the replacement. It could be as simple as the tip of the plug was hit closing the gap too much. Or a cracked spark plug ceramic.

Pull the plugs again one at a time and check the electrode gap. Or just replace them again correctly.

 

What plugs, brand? Did you torque down to correct specs? All vacuum lines connected? Unfortunately, you going to need to do it all over again. You should have no problem with fuel system at 50000 miles so its something you did.

 

And you probably be right. I have a hard time accepting bad plug(s) Maybe it's the first for me but I have never had a bad plug before. These are Denso/Toyota plugs so I thought they're pre-gapped. But just to be sure I've ordered a new set of plugs and will make sure it's gapped correctly and do this all over.

 

These are Genuine Toyota (Denso in "Toyota" packaging). Torqued down correctly and everything (i dont' think this matters all that much, at least pertaining to the issue at hand). I already ordered a new set of plugs and will do this all over. *fingers crossed*

 

There has been a rash of "counterfeit" Denso and NGK spark plugs selling online recently.

The ceramic could have cracked during installation. It doesn't take much of a fracture in the ceramic to cause a problem. I would recommend always checking the gap on a spark plug before installing it.

Good luck, I hope the new plugs solve your issue.

 

I did a spark plus change recently and ordered OEM Densos, none of them were gapped to spec. Had to widen them all.

Hope you find the problem.

 

Does it feel/sound like you are running over rumble strips? If you have torque converter shudder that's what it is like.

 

My truck just recently developed a vibration under acceleration starting around 30 mph, I've diagnosed it as torque converter stutter, gonna change my atf and add lube guard. I have 120k miles, trans service was done @ 92k miles by dealer when they were replacing my frame, I'm guessing they just dumped the pan, 3 quarts, and called it good.

 

BINGO!!! So I ordered a new set of spark plugs and guess what I found when taking out the previous set. One of the plug's ceramic was cracked on both sides.

 

That is one nasty crack.