05-18-2020, 06:28 PM
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#1
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Join Date: Feb 2020
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Real Name: Danny
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Update on Weird misfire problem
Fixed. Very easy fix. But this is a case where I knew too much but didn't know 1 very important thing. A little refresher. This thing starting misfiring on the highway and I connected my scanner and it had misfires on #1 and 2 cylinders. They both started at the same time and they both misfired at exactly the same time. That's what made it so weird. On the day it happened I replaced the plugs on engine bank one and moved #1 coil to #3 cylinder and vice versa. (I didn't change the bank 2 plugs cause I was working in an Advance Auto Parts parking lot with a terrible set of tools.) That didn't change anything. Later I switched the #2 coil with another one. Still no change. I had to leave it at home for the last month while my wife and I were out of town. So the first thing I did today when we got home was call Identifix. The Toyota specialist there told me the one small thing that I didn't know about Toyotas, even though I've been working on them for 30 years. That is: You can't trust the misfire monitors on a Toyota. Mine was telling me it was misfiring on 2 cylinders. He said it could just be one cylinder and it could be a totally different one than either of the ones it said it was. So I went to it and did a power balance test and found out it was misfiring on #2 cylinder only. So I set out to move another coil to that cylinder. I decided to go ahead and put the other three plugs in while I was there. So I put them in and switched #2 coil with the #6 coil. When I started it up there was no more misfire. I expected it to misfire on #6 but no, no misfire. I drove it about 5 miles putting it under a load, (which is when it misfired the worst). I watched it with the scan tool and there was not a single misfire. So the final verdict is a bad plug on #2 cylinder.
What's so funny is any backyard mechanic would have fixed this just by replacing the plugs. And truthfully I didn't spend more than about an hour total working on it. But I spent many hours thinking about it. Because I'm an experienced technician I was able to rule out many things that it (couldn't) be. Just by learning that the misfire monitor is not reliable was all it took to figure it out. I thought if it said #1 and #2 were misfiring, they were. But, anyway, I'm very happy to have it fixed without spending a lot of time or money on it. I may go ahead and order a set of coils for it anyway. And as I've learned over the last 30 some years, when it comes to auto repair, never say never. I'd like to sincerely thank everyone who offered help with this. I do appreciate it. And I will continue to offer my help to anyone else on here when I think I have something worthwhile to say. Thanks guys.
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05-18-2020, 07:03 PM
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#2
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Senior Member
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Join Date: Nov 2016
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Real Name: Skip
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Senior Member
Join Date: Nov 2016
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Glad you got this solved!
I sorta been following your issue because I've been doing mechanic work for over 45 years and you had me a little bit perplex as well....sometime we can be too smart for our own good it seems and miss the simple things!!
I learned years ago when confronted with such a seemingly complex issue to check simple fixes first, I think I may have replaced the plugs first but I also may not have because "It can't be that simple can it"! LOL
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2004 Limited V8
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05-18-2020, 08:33 PM
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#3
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Join Date: Feb 2020
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Real Name: Danny
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Member
Join Date: Feb 2020
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Quote:
Originally Posted by AuSeeker
Glad you got this solved!
I sorta been following your issue because I've been doing mechanic work for over 45 years and you had me a little bit perplex as well....sometime we can be too smart for our own good it seems and miss the simple things!!
I learned years ago when confronted with such a seemingly complex issue to check simple fixes first, I think I may have replaced the plugs first but I also may not have because "It can't be that simple can it"! LOL
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You're so right about being too smart for our own good. I'd like to think I would have changed the spark plugs too if my situation had been a little different. The day it started acting up we were driving home from our place in the NC mountains to our home in SC, just to cut the grass and check things out and we had to return to the mountains the same day. So I changed the bank 1 plugs at the Advance Store but when we got home I didn't have time to do the bank two ones. In fact we were late getting home due to the problem with the t4r and I didn't even get all the grass cut. (The county our mtn place is in had a 10:00 PM curfew in place at that time due to covid). It's a long story why we couldn't just stay at our SC home overnight, but it wasn't possible. Anyway, I'm elated that it's fixed without a lot of time or money invested. And as usual, I learned something new from this. Take Care,
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05-19-2020, 07:29 AM
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#4
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Join Date: May 2018
Location: Swampy and Sunny
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Glad to here it, An image of the plugs electrode would be nice, especially that #2.
P.S. Welcome home !!!!
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NATO Seasparrow Mk 57 Mod 2 & 3
2004 4th Gen Sport Edition
Last edited by Seasparrow; 05-19-2020 at 07:31 AM.
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05-19-2020, 09:45 AM
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#5
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Nice fix, what brand were the plugs and how many miles on them?
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05-19-2020, 06:01 PM
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#6
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Join Date: Feb 2020
Location: Lake City,SC
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Member
Join Date: Feb 2020
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Quote:
Originally Posted by Seasparrow
Glad to here it, An image of the plugs electrode would be nice, especially that #2.
P.S. Welcome home !!!!
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I'll have to see if I can figure out how to post a pic on here. In the meantime, I'll describe it. Normal wear. #2 looked just like all of the other five. They were all worn completely out. And thankfully, no evidence of any other problems like oil consumption, coolant intrusion or fuel mixture problems. I guess you could say they looked really good, other than being way overdue for replacement.
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05-19-2020, 06:17 PM
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#7
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Join Date: Feb 2020
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Member
Join Date: Feb 2020
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Quote:
Originally Posted by waypoint
Nice fix, what brand were the plugs and how many miles on them?
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The old plugs were Denso as were the ones I installed. I just bought this 4runner about 3 months ago. It has 271k on it so I seriously doubt they were original but I will say the plugs had a lot of miles. In fact, I wouldn't be scared to say they likely had at least 100K on them. They were that worn out. And since they are not iridium or platinum they should be replaced every 30K.
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05-19-2020, 06:30 PM
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#8
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Senior Member
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Senior Member
Join Date: Nov 2016
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Quote:
Originally Posted by importman
The old plugs were Denso as were the ones I installed. I just bought this 4runner about 3 months ago. It has 271k on it so I seriously doubt they were original but I will say the plugs had a lot of miles. In fact, I wouldn't be scared to say they likely had at least 100K on them. They were that worn out. And since they are not iridium or platinum they should be replaced every 30K.
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If all 6 were Denso they weren't the original plugs, all 4th Gen V6s came with NGK in one bank and Denso in the other bank, this is because it is said that the heads came from different factories and the factories had different brand plugs supplied to them and the plugs are installed in the heads before shipping them to be installed on the block.
That being said there are many posts on these forums where someone changed out their plugs on the V6 at well over 100,000 miles and sometime much more and it still had the 2 different brands plugs and if they posted a photo of the plugs most looked to have a gap of around .080, instead of the .043 or so normal gap
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2004 Limited V8
Last edited by AuSeeker; 05-19-2020 at 06:56 PM.
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05-19-2020, 07:04 PM
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#9
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Member
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Join Date: Feb 2020
Location: Lake City,SC
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Real Name: Danny
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Member
Join Date: Feb 2020
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Real Name: Danny
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Quote:
Originally Posted by AuSeeker
If all 6 were Denso they weren't the original plugs, all 4th Gen V6s came with NGK in one bank and Denso in the other bank, this is because it is said that the heads came from different factories and the factories had different brand plugs supplied to them and the plugs are installed in the heads before shipping them to be installed on the block.
That being said there are many posts on these forums where someone changed out their plugs on the V6 at well over 100,000 miles and sometime much more and it still had the 2 different brands plugs and if they posted a photo of the plugs most looked to have a gap of around .080, instead of the .043 or so normal gap
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That's interesting. Oddly, the gap on my old ones looked really large. The replacements were more like the spec you quoted. Incidentally, I fully trust the Densos but If I'd had the option of getting NGK's at the time I bought them, (on the road while I was having trouble), I would have gone with them. I'm a big fan of NGK. When I had my shop, on more than one occasion I was able to correct running problems on vehicles simply by replacing A/C or Autolites that my customers had just installed, with NGK's. Best plug available for my money.
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05-19-2020, 07:12 PM
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#10
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Senior Member
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Join Date: Nov 2016
Location: South Carolina
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Real Name: Skip
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Senior Member
Join Date: Nov 2016
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Posts: 4,617
Real Name: Skip
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Quote:
Originally Posted by importman
That's interesting. Oddly, the gap on my old ones looked really large. The replacements were more like the spec you quoted. Incidentally, I fully trust the Densos but If I'd had the option of getting NGK's at the time I bought them, (on the road while I was having trouble), I would have gone with them. I'm a big fan of NGK. When I had my shop, on more than one occasion I was able to correct running problems on vehicles simply by replacing A/C or Autolites that my customers had just installed, with NGK's. Best plug available for my money.
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Both Denso and NGk are great plugs, it's also apparent that Toyota thinks so as well since they used both brands in the same V6 engine from the factory, so either can be considered OEM.
That being said if you buy plugs for a V6 or V8 from a Toyota dealer it will be Denso brand.
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Last edited by AuSeeker; 05-19-2020 at 07:14 PM.
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