misfires after new spark plugs. Need help !!!

[Jacko84]

On Saturday I replaced my spark plugs after 152,000 miles. I wasn’t having any issues but I figured that I was about time. I went and got the plugs from the dealership and read the very helpful write ups on how to do it in this forum. After following careful direction, I completed the project Without any hiccups. Didn’t have to remove the air intake since it’s a 2011 and disconnected the black battery wire. Started up and idled as usual. Took it for a test drive and I started getting misfires. These misfires only happen at low torque, between 2000 and 1500 RPMs and with about 10% to 15% throttle. Went back home after this and restarted the whole process again thinking I may have over torqued one of the plugs or that I didn’t properly check the gap. After double checking and confirming that everything was up to par, I took it for another test drive and The same symptoms occurred. Went back Home and this time checked all the connectors to the coils, checked to make sure that the male side of the connector looks OK, no pins bent, etc. From an electrical standpoint everything looks OK. I have driven the 4runner like this for about 35 to 40 miles and it’s still not throwing any codes. I am getting 13 mpgs. My thinking is that one of the plugs may be defective or cracked or maybe even one of the wires for the connectors is lose, however, this is nothing that I can confirm Visually. Any help would be greatly appreciated

 

[Gt4r]

Did you use a steel gap tool? Iridium is really brittle and you may have damaged the electrode.

 

[Jacko84]

Did you use a steel gap tool? Iridium is really brittle and you may have damaged the electrode.

Not sure if it’s steel but it’s one of those that looks like a coin from AutoZone

 

[spartacus]

is it throwing any codes?

 

[Jacko84]

is it throwing any codes?

None so far. The biggest reason I am perplexed. I wish it would so I can at least know which cylinder.

 

[1jzgte]

put the old plugs back and see if its back to normal.. and go from there

what model and brand are the new plugs?

 

[Jacko84]

put the old plugs back and see if its back to normal.. and go from there

what model and brand are the new plugs?

That’s what I was afraid I may have to do. The plugs are the Denso Japanese brand that I got at the dealership

 

[spartacus]

None so far. The biggest reason I am perplexed. I wish it would so I can at least know which cylinder.

you can still check for pending codes. also when you have the misfire at lower rpms and you put more load on it does it smooth out. if it does then check if accidently created a vacuum leak check all vacuum lines are good. if all that checks out could be a possibility of a bad plug not unheard of.

 

[03_4x4Runner]

In the old days we used to unplug each spark plug one at a time to see if the miss got worse to find the bad plug. Not sure if this is advisable on newer computer controlled cars. Maybe use a heat gun on the exhaust manifold to see which cylinder is colder?

 

[Jacko84]

you can still check for pending codes. also when you have the misfire at lower rpms and you put more load on it does it smooth out. if it does then check if accidently created a vacuum leak check all vacuum lines are good. if all that checks out could be a possibility of a bad plug not unheard of.

That what I thought so I took it to the Toyota dealership and a very nice service advisor scanned for any pending codes @ no cost, he even drove it to feel the symptoms, came out negative. When I give it more throttle it still does it until after 2000 rpms. It does it very little at idle and not always

 

[spartacus]

That what I thought so I took it to the Toyota dealership and a very nice service advisor scanned for any pending codes, came out negative. When I give it more throttle it still does it until after 2000 rpms. It does it very little at idle and not always

Is it a vibration or a distinctive miss. because a miss under load is more of a jerking motion and not just a vibration.

 

[Jacko84]

Is it a vibration or a distinctive miss. because a miss under load is more of a jerking motion and not just a vibration.

Definite misfire. Short Sudden loss of power

 

[spartacus]

Definite misfire. Short Sudden loss of power

oksy. now if I was you and had this issue I would take the spark plugs back and have them swap it with new ones that are pre gapped and install them and go from there.

 

[1jzgte]

That what I thought so I took it to the Toyota dealership and a very nice service advisor scanned for any pending codes @ no cost, he even drove it to feel the symptoms, came out negative. When I give it more throttle it still does it until after 2000 rpms. It does it very little at idle and not always

Could they have possibly sold you the wrong spark plugs? I would slap the old plugs back in and see how the car reacts.

 

[Jacko84]

Could they have possibly sold you the wrong spark plugs? I would slap the old plugs back in and see how the car reacts.

Checked for correct part number and visually compared each one to the old ones

 

[Desid]

the ceramic could be cracked causing the spark to not go through the plug properly.

 

[Akkording]

and you're positive you don't didn't plug in the spark plug wires in the wrong order?

 

[wfo9]

Your telling us you can detect the misfire but the computer can't. I know Toyota diagnostics and engine controls are bad.. but not that bad. EPA requires that test to be pretty darn accurate.

I'm guessing not a misfire and more likely the trans... But total guess. Rarely does a misfire not get detected with a CEL to see the change in crank speed. It's a pretty simple mechanism and better than any human in most cases.

 

[Jacko84]

and you're positive you don't didn't plug in the spark plug wires in the wrong order?

Couldn’t have because I do them individually.

 

[Jacko84]

Your telling us you can detect the misfire but the computer can't. I know Toyota diagnostics and engine controls are bad.. but not that bad. EPA requires that test to be pretty darn accurate.

I'm guessing not a misfire and more likely the trans... But total guess. Rarely does a misfire not get detected with a CEL to see the change in crank speed. It's a pretty simple mechanism and better than any human in most cases.

Yup, that’s what the Toyota tech and service advisor said until they drove it and felt the misfire. Drove and ruled out transmission. Specially since there have been no symptoms whatsoever until the new plugs.