Sparkplugs changed from Toyota to denso and reduced performance

Just to add to this as it might be helpful...

I changed the spark plugs on my Gen 2 Prius 6 months ago.

After getting the new plugs I too had power issues while driving.

At the same time I had also done a piston soak and had rotated the crankshaft manually.

All this was done without disconnecting the battery.

When I installed the new plugs I had significant power issues from the engine.

I think I screwed up the crankshaft position sensors calibration by rotating the crankshaft with the vehicle off.

It wasn't until I disconnected the 12v Battery to reset the computers that my engine power returned.

Moral of the story, maybe something the mechanic did could be fixed by a 12v disconnect that resets the learned memory of the sensors/computers.

Posted via the PriusChat mobile app.

 

Cool I don't know? I have never had hood up on a Prius C? I can only recognize the C's that are the Mopar Tangerine Orange. We have a couple of them around here, or I don't know maybe I see the same one twice?

So a "inch torque, wrench," and I don't know if those come in a 3/8 size? Or a "Stubby, 3/8." and a bit of "Good Sense," and he should be fine.

 

Just moving the crank, and changing the spark plug's? Should have made "Zero Difference?" As far as the engine is concerned, nothing would be different?

I rotate piston's all the time to get cylinder's to "TDC," to check stuff. It makes no difference to the Spark Plug's or engine timing AFIK?

 

As Pri3C said, there are other Prii where getting to the spark plugs can be a chore, but it isn't difficult in a Prius c.

You don't need any power tools at all, and in fact, if you're not familiar with such work, simple hand tools will be both less expensive and less likely to get you into trouble while learning.

You can get the idea from a video like this one:

As you can see, there is an ignition coil over each spark plug, and each ignition coil is held down by a single bolt, which has a 10 mm head. (Some people will call that a "10 mm bolt", but don't make that mistake; when we talk bolt sizes, we give the diameter of the threaded part, which is 6 mm for these.) To loosen it, you can use a simple 10 mm open-end wrench or a 10 mm socket in a socket set.

If you don't have a socket wrench set of any kind, an inexpensive set is easy to find just about anywhere, and has a gazillion uses around a home.

If you buy a socket set, you can probably find one that includes a "spark plug socket". Those come in different sizes. If it comes with a 16 mm (or non-metric 5/8 inch) spark plug socket, you're all set.

While shopping for a socket set, you might see if there is an inexpensive "torque wrench" for sale, ideally a "click" type, maybe a medium sized one with a range of, say, ten foot-pounds up to maybe 75 foot-pounds, or even a smaller one, perhaps with a 25 to 250 inch-pound range. The smaller one is even preferable for spark plugs, but the medium one will work too and might cover more other common uses.

You'll find the little bolt only takes a little bit of force to (lefty-)loosen it at the very start, and you can spin it the rest of the way out with your fingers.

Pay attention to what that little bit of force to loosen it felt like. Later on when you put it back and tighten it, you don't need more force than that. It's easy to overdo the force on small bolts.

With the little bolt removed, the ignition coil just lifts up and out of the way. You can unplug all four electric connections to those coils, but the video seems to show at least a couple of them have enough wire slack that you can lift the coil up and out of the way without even having to unplug it.

With the coil out of the way, all you need is your spark plug socket on an extension on your socket driver handle, and again a little bit of lefty-loosey force will loosen the spark plug. As you see in the video, after it is loose, you can set the driver handle aside and just turn the extension with your fingers until the plug is loose, and lift it right out. A "spark plug socket" usually has some rubber in it that grips the plug so it stays in the socket when you lift.

The video gives good information about plugs possibly being hard to unscrew, but that's usually after they've been there for tens of thousands of miles. If these were just installed recently, you should have no problem unscrewing the plug.

I suggested posting photos not just so we can confirm the plug type, but so we can see what the condition is. Being new, it should look pretty new. A photo might give some sense of any issues.

Reinstalling the plug is where you need to use some delicacy. You'll just put the plug into the spark plug socket, hold it by the socket extension. lower it down into the plug well, and feel for when it starts in the threaded hole at the bottom.

You can twist the extension gently with your fingers, to the left and right, to feel when the spark plug threads enter the threads of the hole. You don't want the angle to be off, or to start new threads in a different spot.

The guy in this video mentions a grease for the spark plug threads (but says he forgot to bring it). Denso does not recommend greasing the threads.

Something I usually do is rotate the extension slowly to the left (the loosening direction). That sounds backwards, but at some point (within a full turn or less) you'll feel a little drop as the plug drops down by the height of one thread. That has found you exactly where the threads begin, and now you can turn the extension to the right with your fingers to spin the plug the rest of the way in. When it is no longer easy with fingers, you just finish up with the wrench.

Spark plugs are also things you do not want to overtighten. If you bought a torque wrench, and it is marked in foot-pounds, you would set it for 15 foot-pounds. If you bought one marked in inch-pounds, that's 180 inch-pounds (obviously, you do not want to mix these settings up!).

Once the wrench is set appropriately, you can just use it gently to tighten the plug until the wrench handle makes a little click that you can hear or feel. It will not feel like much force at all.

If you didn't buy a torque wrench, you can do this without, but be very careful to notice how much force you used to loosen the plug, and don't overdo that when tightening. (When the plug has been there for tens of thousands of miles, it can take extra force to loosen, and then that would be a bad example of the right tightening torque. But if it was just installed a short time ago, the loosening force should still be a decent indication of how to tighten it.)

Then you just set the ignition coil back down over the plug, start the little bolt for holding it down (you can start that with your fingers, much the same way as you did the spark plug), and finish it up with a wrench, using no more force than you remember using to loosen it. If you unplugged the wiring from the coil, plug it back in.

If you unhooked any wiring supports the way the video shows, put those back too. That's all.

 

45 posts for twenty dollars worth of spark plugs?

 

No, I'm just saying not to confuse the size of a bolt head with the size of the bolt.

The ignition coil is held down by a 6 mm (aka M6) bolt, with a 10 mm head.

You turn the bolt with a wrench that fits the head, so you would reach for a 10 mm socket or a 10 mm open-end wrench.

But if you ever needed to buy a replacement for the bolt itself, you would look for a 6 mm (M6) bolt. If you asked for a 10 mm bolt because that's its head size, you would get a bolt the wrong size.

Or (here's where the confusion can get costly), suppose you are tightening a bolt, and you want to get the torque right, and you find a chart that gives tightening torques for different bolt sizes. If you mistake the head size for the bolt size, so you look up the torque for a 10 mm bolt when it's really a 6 mm bolt, the chart would give you a much too high value, and you would likely break the bolt right off.

So that's why it's just important, right from the start, to make yourself remember that the size of a bolt and the size of its head are different. The wrench naturally has to match the head.

"Tricky" is relative. You sound kind of mechanically inexperienced, so that's where I'm starting from. Just the feel of how you get a threaded bolt or spark plug gently started in a hole, straight, without crossing the threads ... it is not very difficult, but it is worth focusing on the first few times you do it. It quickly becomes natural.

For any mechanic like the one who installed your spark plugs, it has probably already been natural for years, if not decades.

There can also be trickiness when dealing with spark plugs being replaced after a typical life span (120,000 miles for these!).

You are very unlikely to face that kind of trickiness if the plugs in question have only been there 6 months.

 

Sometimes, you have to start small and work your way up.

 

If 50¢ for a PriusChat post holds in general, bisco's are worth $46k.

 

First off, I think @ChapmanF needs a medal, that’s very thorough.

regarding the inch pound conversion: it may be obvious but anyway, inch pounds are foot pound values times 12, and vice versa.

 

They put a really nice compression gasket on spark-plugs. For most guys with any automotive experience at all or who have watched any decent video you can see that they should be hand snug then finished with a quarter turn. The same is true with oil filters but we usually just say "hand tite".

I'm not saying that you won't find a video of guys using torque wrenches ... and I'm not at all saying that if you want to get one and use it that it's a bad idea. Enjoy yourself. It can't hurt. What I'm saying is that unless you're completely unskilled with NO simple skills at all ... a torque wrench for spark-plugs is over-kill and unnecessary.

As to that video in post #44 ... It's very nice. I would suggest not at all using any power-tools for jobs like this. I also prefer to do 1 plug at a time. They guy didn't use any but he did mention "anti-seize" for the threads. I highly recommend this stuff. It comes cheap in a little tube. Just be careful and don't put too much on. "A little dab will do 'ya.".

 

Ok 1.5 so same as the Gen ll, kinda odd but whatever. :

And as Chapman said it is very unlikely that the Mechanic screwed up Replacing the Spark Plug's? I mean sometimes crap happens but it is highly unlikely? It is a simple job (simpler on the 1.5 then the 1.8 apparently.)

You shouldn't have to take off the Windshield wiper's and cowl to change freaking spark plug's but I digress.

It is a simple job "BUT," you can do significant damage if you mess it up. Cross threading the plug's is the biggest danger. If you cross thread or over torque the sparkplug's your screwed. So you know, don't do that.

So a couple of tip's. When reinstalling spark plug's, I always use anti size compound on the threads, not on the tips however. You can use a q-tip to apply just enough anti size to lightly coat the threads. It keep's the threads from sizing up in the head. Which probably is not an issue since they were just replaced. But I always reapply anti size myself.

And for reinstalling the plug's, I always, reinstall the plug's using a foot or so of 3/8 inch fuel line. (I think that is the size?) You slip the hose over the ceramic part of the plug and use the hose to start and reinstall the plug. If you use a length of hose to start threading the plug, it is almost impossible to cross thread them.

And another tip, if you have truly never installed any spark plug's? Gather up the tool's you think you'll need and go to a local pick and pull. And "practice," on a "Dead Prius." It's a great way to see what you'll be dealing with and not damage your car.

 

If you use anti-seize you should reduce torque value, from the dry thread torque spec of 15 ft/lb, to say 12~13. Oh, I forgot: torque wrenches are for the completely unskilled.

 

Well what you say is absolutely correct. And I am sure that most of us that have been wrenching on car's for awhile, have never used a "Torque Wrench," for installing Spark Plug's?

And while Snug and a quarter turn, works for folks that "know what they are doing," for JQP that has never turned a wrench, on a car in there life, not so much? JQP does not know what "Snug," means or a "quarter turn?"

That is not how "newbie's," think? They believe, that if you want those Spark Plug's to stay in, you have to Crank the He$$, out of them so they don't fly out? And "if," they do that? When they hear a "Snap?" They'll know they got it wrong? Now that is "also," a great way to "understand how much (torque) is too much torque? But it can be an expensive way to learn?

An (inch pound) torque wrench would be a PIA, to use for "Spark Plug's," I'll grant that. But if you have never used a wrench in your life? The proper use of one can save one from doing a lot of expensive damage. Better safe than sorry.

 

"Hand snug then finished with a fractional turn" can be used, but the fraction isn't always a quarter, and it depends (a lot) on whether installing a new plug or reinstalling an old one.

Denso provides a table where you can look up the specific plug (and whether new or used):



For simplicity, the "used plug" figure is about a twelfth of a turn across the board (except for the tapered-seat type, which these aren't). It's the "new plug" values that differ more between plug types.

One nice thing about using the torque value is the same torque applies whether the plug is new or used.

If Toyota gives a torque spec of 20 Nm or 15 ft-lb, I notice that's right at the low end of the range Denso is giving here for M14 plugs. That probably means if you choose to disregard Denso's "Do not use a thread lubricant", you might not be courting disaster, as long as you're not tightening past Toyota's spec.

 

Good catch but we are not talking con rods or bearing cap's or suspension component's. But you are indeed correct about the correction factor for "anti size."

But I don't think anyone is "attacking the value of Torque Wrenches'?" It's just that for Spark Plug's most of us don't use them.

 

you get what you pay for

 

I know that have the ability to really work people's nerves. I'm not necessarily proud of that. Now whereas if you look, I think I qualified my wise-crack statement about the torque wrenches.
"... and I'm not at all saying that if you want to get one and use it that it's a bad idea. Enjoy yourself. It can't hurt.".
I'm still gonna apologize to anyone who might have taken offense. Mendel Leisk, in NO way was it directed at you.

For Me ... I use a common ratchet extension to spin the NEW plugs in until they are hand snug. The plugs have been dabbed with some anti-seize prior. I then go 1/4 turn with the ratchet. Now maybe for the last 50+ years I've just been the luckiest guy that ever worked on a car, but I've never had any problems. I've never seen ever anyone use a torque wrench for spark plugs. Maybe they all hid them when I was looking.

On another topic ... I don't think you need to use Toyota as your only outlet for parts. I also don't think you should get your parts from eBay either. Any good name-brand parts store will be just fine. For the past 10-years at least I've been using RockAuto. All quality parts for the lowest prices. ... NO ... I don't work for them. ... "QUALIFIER" alert: ... Spend your money wherever you like. I'm not the "Shell AnswerMan" for everything. I'm only having CONVERSATION like I would think many of youse guys are also doing.


I also apologize for my use of a larger font. I'm having eyesight/migraine issues.

 

Well thanks, but I don't think you need to apologize for anything. People can take "perceived slight's," for just about anything these day's? And a "torque wrench?" Apparently is one of them?

I to have never seen anyone use a "Torque Wrench," for Spark Plug's? It would be time consuming and awkward to do so, I would imagine? And I can't say I have ever factored in anti size, in doing the "snug and 1/4," turn bit for installing Spark Plug's? But hey it is a "factor," and most likely F1 team's and OEM's do consider it? I doubt those guy's free hand "Spark Plug, installation?" Most likely those guy's use "Calibrated Torque Gun's," just for that purpose?

And while installing Spark Plug's is simple as dirt for many of us? And as such a Torque Wrench, is way over kill? For some folk's maybe not so much? Changing Spark Plug's, Gen III, notwithstanding, is a simple job. But if you over torque the Spark Plug's ... your in a world of hurt!

Snug or Hand tight and a 1/4 turn? Is subject to interpterion? A properly used Torque Wrench, is not. A man/girl, has "got to know there limitation's?"
It's pretty much that simple.