Misfire no CEL

bdubbin said:
Oooo... data!!! I don't know anything about this but it's interesting!
I watched this https://www.youtube.com/watch?v=pIJdCZgEiys and it seems you're running rich. He lists some possible causes and begins troubleshooting but his condition is lean with a high + ltfr number. The first 7 minutes seem applicable to you.
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Thanks for the video. Guess I'll start at square 1 and clean the MAF. Also picked up a pcv valve as it was only $5 and I've never replaced mine.
 
blindloser1080 said:
Did some driving around the block for about 10 minutes, max speed 40mph (having hesitation and misfire when stopping at a light and going again). Here's some info I found out:

Long term fuel trim bank 1: 0-4.7%
Short term fuel trim bank 1: -15.6%-9.4
Long term fuel trim bank 2: 3.1-6.3%
Short term fuel trim bank 2: -19.5%-7.8%
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Missed this. My bad. I think negative fuel trims mean you are running rich and the computer is throttling back on fuel delivery.
 
I stand corrected. I got it backwards. Positive trim means the engine THINKS it's lean and dumps more fuel. Negative trim means it THINKS it's rich and cuts back on fuel. Your actually running lean. The voltages of the sensors seem askew for the trim data, I feel like you need to look at the o2 sensors as I suspected. The engine THINKS it running rich because it's getting incorrect data from the sensors, so it's throttling back to make the o2 sensor read correctly. Sorry, my bad
 
blindloser1080 said:
So if I'm reading it correctly, bank 2 sensor 2 needs to be replaced?
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I would say both banks, start with sensor 2, should be past the cats. The computer uses both sensors to determine the amount of oxygen and unburnt fuel in exhaust. Sensor 1 is harder to get to, I'd try the easier accessed sensors first. Though you may want to just change all 4 since they work in pairs per the respective bank. Both short term trims are kind of high. Normal should be 0 to +-10, occasionally dipping up to 12 or so. Are you noticing a higher engine temperature? Common on older engines running lean, also common to have a rotten egg smell from the tail pipe.
 
Thank you. Went on ahead and ordered both the downstream Densos off Amazon and they'll be here Tuesday (nobody local had the Densos). I haven't noticed any rotten egg smell or higher than usual temperatures.
 
08TxRunner said:
Didn't know there was a problem with fake plugs for the wrong application being sold. Got any links?
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I don't have any links but plenty of people have complained about buying densos online that have turned out to be "fakes".

As far as the comment about wrong application, that was because I figure that a parts desk at the dealer would be more accurate with their parts than say a big box auto part store.
 
Replacing both the downstream sensors today. After replacing them, do I need to pull the battery cables off and let it sit for a bit? Or am I good to start driving once they're replaced.
 
blindloser1080 said:
Replacing both the downstream sensors today. After replacing them, do I need to pull the battery cables off and let it sit for a bit? Or am I good to start driving once they're replaced.
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Not a bad practice. With modern vehicles, the computer stores and remembers everything. Blanking it out will make it relearn so if there is another problem it will be obvious. Don't be alarmed, engine will start and die the first time. That's normal, start it again and it should be fine
 
81runner said:
Not a bad practice. With modern vehicles, the computer stores and remembers everything. Blanking it out will make it relearn so if there is another problem it will be obvious. Don't be alarmed, engine will start and die the first time. That's normal, start it again and it should be fine
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Thanks, will most definitely do. Just got both the sensors installed. It definitely didn't misfire nearly as much as it was before with the old sensors. Maybe 6 times total? And that was at the very beginning of my drive. On the way back, nothing that I noticed.
 
blindloser1080 said:
Thanks, will most definitely do. Just got both the sensors installed. It definitely didn't misfire nearly as much as it was before with the old sensors. Maybe 6 times total? And that was at the very beginning of my drive. On the way back, nothing that I noticed.
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Right on. Sounds promising
 
Unplugged the battery for a good 20 minutes. Drove around town, around the freeway 55-60mph no problems for about 30 minutes. Stopped at the store, decided to take it on the freeway... it starts happening again. Same misfires at 55-60 and sometimes at low like 25 whenever I'm at the 1800 rpm mark.

Any other thoughts?
 
blindloser1080 said:
Unplugged the battery for a good 20 minutes. Drove around town, around the freeway 55-60mph no problems for about 30 minutes. Stopped at the store, decided to take it on the freeway... it starts happening again. Same misfires at 55-60 and sometimes at low like 25 whenever I'm at the 1800 rpm mark.

Any other thoughts?
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Check your fuel trims and O2 sensor voltages again and see if anything changed after putting in the new sensors.
 
So I decided screw it. Called the Toyota specialist here avx they ran a diagnostics on it. My 3rrd coil is bad. They hooked it up to a computer and found the misfire. Moved the 3rd coil to #5 and the misfire moved with it. So off to buy a new coil!
 
blindloser1080 said:
So I decided screw it. Called the Toyota specialist here avx they ran a diagnostics on it. My 3rrd coil is bad. They hooked it up to a computer and found the misfire. Moved the 3rd coil to #5 and the misfire moved with it. So off to buy a new coil!
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Any idea how they test for that?
 
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