Stutter while accelerating

Hi everyone!

So lately I’ve been noticing that when accelerating or keeping the engine at cruise control, in the range of 1500-2500 rpm, the whole truck shakes/jerks like it’s hitting multiple speed bumps at a time, but the road is relatively smooth (highway). I used my BlueDriver scanner to check for any codes and used mode 6 plus live data, but nothing came up. Everything seems to be in order, all mode 6 data tests have passed, and nothing out of the ordinary aside from the intake temperature being higher than ambient (highest was 90 over 64)

I suspect it’s a misfire, and a pretty bad one. Note:I checked the air filter and it was very grey and had leaves in it, of course (dumb@$$ moment ).

This began to happen after I had taken the truck in to inspect the brakes, and to install switchback light assemblies and fog lights a week ago.

I’m getting a DENSO replacement one tomorrow, but I’d like to know if a clogged air filter can cause misfires, and what other things can the cause of this issue, besides the air filter. My current mileage is 154604.

Please do not hesitate to call me out on my mistake LOL

 

Update: Can now confirm: scan reveals code P0304 - Cylinder 4 misfire.
Noob question here, but since the 5VZ-FE has a waste-spark ignition system, wouldn’t that also imply that the coil could be at fault or it’s just the spark plug?

 

If it were a bad coil pack, you'd probably see a misfire on two cylinders. But it's on #4, it's more likely a wire or plug. Could also just be a poorly seated wire. But guessing that if you had leaves in your airbox, the plugs and wires probably haven't been touched in awhile either. Just replace the whole lot.

 

Probably worth your time to clean the MAF too, even though it's not likely the culprit, but with an air filter that dirty, it's hard to imagine the MAF being spotless.

 

Yeah sounds like new spark plugs or wires.
Another thing that will cause odd misfires is having an air leak behind the MAF sensor.
I cleaned my throttle body once and didn't install my air intake pipe correctly and was sucking half of the air in right before the throttle plate (behind the maf) and the engine stuttered and stumbled until i figured it out.

 

Thanks for that.

Also, two other things: does the 5VZ-FE have dual-electrode or single-electrode plugs? I’ve ordered a set of 6 DENSO double platinum plugs (there weren’t any dual iridium ones) for my V6, AND if upgrading the plugs is a good idea in terms of longevity, reliability, cost and general quality. I saw a video from Scotty Kilmer saying he replaced the original copper plugs on his ‘94 Celica to iridium ones because of the plugs were under the intake manifold, implying they last longer.

 

That’s a good idea. Though I’ve checked the engine bay and air box + the vacuum line running off of it - seems like they were all secure. Though using the scanner, I noticed that the intake temperature was almost 40 degrees higher than ambient temp. Let’s say it’s 78 outside - scanner reads 118. I’m not sure if the engine has an air charge sensor, but if it does, where would I find it, and how can I fix it besides replacing all 6 plugs+wires?

 

There should be a sticker on the timing belt cover that has the original plug specs. You can also download the owners manual for your truck here: https://www.toyota.com/owners/resources/warranty-owners-manuals

They are twin ground electrode:


Spark plugs in terms of "performance" is a bit of a . Shy of installing a supercharger (and all that entails, spark plugs included), you're not going to notice a bit of difference between new OEM spec, platinum, iridium, etc.. As long as you replace them in normal intervals it's fine. You don't have to worry about removing the intake manifold to get to the spark plugs. Just the intake tube.

You should also look into replacing all your vacuum lines. Just easy maintenance.

 

Duly noted. Lastly, three other things:
1) What is the factory plug gap spec and where do I find it?;
2) What tools should be used when gapping a twin-electrode spark plug and how to use them (first time replacing my plugs myself)?; PS to point 2: If a plug gap tool is needed, what specific style/design of tool must be used for a twin-electrode plug?
3) And finally, is it a generally good practice to replace the ignition coil boots alongside the wires/plugs?

Note: all parts mentioned above are manufactured by DENSO, so it’s close to OEM. Thank you for your help!!!

 

1) Again, owners manual has you covered:


2) There is actually NOT a good answer for this. It's a rabbit hole- see this thread: https://www.tacomaworld.com/threads/3-4-denso-dual-electrode-gapping.374023/ Most (myself included) have not been able to find the correct style gapping tool for the .043.

3) I have not changed the coil boots, but I'm only at 150k on original coils. I would only change them out if I had a reason to.

4) Not that you asked, but I'll add this anyway. There is constant debate on whether to use anti-seize on the plug threads and how that affects the torque spec. People believe strongly one way or another. I don't care I personally have always used a very small dab of anti-seize, and never used a torque wrench. Just hand tight plus a nudge. Never had an issue. Don't try to change the plugs when the block is hot.

 

You shouldn't be gapping good quality plugs right out of the box. It's not 1969 anymore. Besides, where would you even insert the tool on those dual electrode plugs? If you start jamming a gapper down in there you'll just crack something and fuck it up

Stick with oem copper. And check the coil boots and wires closely for signs of arcing. If you can afford it, don't be afraid to just replace the coils, they're almost 20 years old

 

I agree with not gapping the plugs. I checked them outside the box, and each one of them matched each other gapwise. About OEM copper I’ll have to disagree. I’m using DENSO Double Platinum (stated previously) in order to have a greater plug lifespan, as well as resistance to high heat. My ‘04 is a daily driver at speeds in excess of 70mph, with 154k on it already. So I’d rather have the engine spic and span. I’d like to replace the coil packs and boots too, but right now, my budget is tight, so maybe later.

 

Understood. May I ask what kind of anti-seize would you recommend?

 

Dont forget wires. I have had my truck for over twenty years and out of nowhere I have had several issue with massive misfire. Every time it was wires. Many times blue Denso's. These trucks burn wires

 

I mean, if you don't do a lot of work on your truck, or have need for the stuff otherwise, whatever the parts store sells in those little packets at the counter is WAY more than you'd need for the plugs. The stuff goes for miles, and you don't want to use much of it. As I said, just a small dab- it will spread itself when you thread it in.

 

Clear the codes and swap the coil packs around. If the misfire code moves to a different cylinder you know it’s the coil pack. If it remains on cylinder four, swap the plugs, and so on. Just swap one thing at a time and when you get the misfire to move, you know you have found the culprit. Also, could be injectors.

 

I just replaced all 4 coils on my 2.7L. With 390K miles and only having to replace one over 200K miles ago, I figured it was due.
It's like a whole new truck.

 

It was running good, and you changed them for the high miles. Then you noticed a big differance??

 

No, it was lagging when trying to accelerate at around 1800 - 2200 rpms. Then a misfire code popped up for cylinder 3. After checking things out and resetting the CEL, the misfire code never came back. But the lack of acceleration stayed. Since I needed to do the valve cover gasket and change spark plugs, I decided to replace the coils as well.

Could it have been just the plugs? Maybe. But at 390k miles on 3 original coils, I figured it was a good thing to do as well.

 

OP ( @Tony-Tacoma-5121 ) how did you resolve this? What was your solution? I have a similar issue. Thanks!