Help me get to the bottom of my misfire

M-Piers97

M-Piers97

New member
I have a 1997 V6 4x4 auto 4Runner that has been misfiring ever since i bought it back in September. I knew it was misfiring because of the flashing CEL and because it ran like CRAP, so i changed the plugs and wires i used NGK duel electrode plugs and Import Direct wires from O'Reilly's and i am pretty sure the plugs and wires in it were original because all the plugs were DENSO's and the wires said 1997 on them so with 230,000 miles on them they were pretty nasty.

The new plugs and wires made it run better but the CEL still flashed and it had little power so i took it to the local Toyota dealer and had them run the codes, he told me that i had a dirty MAF a bad B1 S2 O2 sensor and a cyl# 3 and 6 misfire so he told me to replace the coil pack.

So instead of paying the dealer 80 bucks for 1 coil pack at Toyota i jumped on Ebay and bought 3 for 60 bucks and installed them myself, took it for a ride and it was still misfiring, so i bought a Bluetooth OBDII reader of Ebay for 10 bucks and ran the codes myself and i have codes P0306 cyl# 6 misfire and P0141 B1 S2 O2 sensor.

So at this point i am thinking bad/clogged fuel injector? or could a B1 S2 O2 sensor cause a misfire? Any help to troubleshoot this would be awesome
 
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Could be a bad injector, pull the #6 spark plug out and look at it. Does it have fuel fouling? Are there any arching marks on the wires? I'm surprised Toyota didn't take a look at your long/short term fuel trims. You can also purchase a stethoscope and listen to the #6 injector to see if it is working.
 
FROGrunner said:
Could be a bad injector, pull the #6 spark plug out and look at it. Does it have fuel fouling? Are there any arching marks on the wires? I'm surprised Toyota didn't take a look at your long/short term fuel trims. You can also purchase a stethoscope and listen to the #6 injector to see if it is working.
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I will try to pull out the plug when i get a chance but as of now in northern Michigan there is 3 feet of snow on the ground and its like 20 F out so working on vehicles sucks, also what does arching on the wires look like?
 
M-Piers97 said:
I have a 1997 V6 4x4 auto 4Runner that has been misfiring ever since i bought it back in September. I knew it was misfiring because of the flashing CEL and because it ran like CRAP, so i changed the plugs and wires i used NGK duel electrode plugs and Import Direct wires from O'Reilly's and i am pretty sure the plugs and wires in it were original because all the plugs were DENSO's and the wires said 1997 on them so with 230,000 miles on them they were pretty nasty.

The new plugs and wires made it run better but the CEL still flashed and it had little power so i took it to the local Toyota dealer and had them run the codes, he told me that i had a dirty MAF a bad B1 S2 O2 sensor and a cyl# 3 and 6 misfire so he told me to replace the coil pack.

So instead of paying the dealer 80 bucks for 1 coil pack at Toyota i jumped on Ebay and bought 3 for 60 bucks and installed them myself, took it for a ride and it was still misfiring, so i bought a Bluetooth OBDII reader of Ebay for 10 bucks and ran the codes myself and i have codes P0306 cyl# 6 misfire and P0141 B1 S2 O2 sensor.

So at this point i am thinking bad/clogged fuel injector? or could a B1 S2 O2 sensor cause a misfire? Any help to troubleshoot this would be awesome
Click to expand...

Was the dirty MAF issue ever addressed? Why don't you try cleaning the MAF and go from there. Seems like the next logical step.
 
M-Piers97 said:
I will try to pull out the plug when i get a chance but as of now in northern Michigan there is 3 feet of snow on the ground and its like 20 F out so working on vehicles sucks, also what does arching on the wires look like?
Click to expand...
Tiny black burn marks, you can sometimes see them on the plug itself or on the wires. I'd def listen to the injector itself to see if it clicks on and off. As far as the MAF goes, i would purchase some CRC MAF cleaner to clean the MAF. I've never seen a dirty enough maf sensor to create a consistent misfire, even after changing plugs and wires. Does the misfire get worse or better as you apply the throttle?
 
FROGrunner said:
Tiny black burn marks, you can sometimes see them on the plug itself or on the wires. I'd def listen to the injector itself to see if it clicks on and off. As far as the MAF goes, i would purchase some CRC MAF cleaner to clean the MAF. I've never seen a dirty enough maf sensor to create a consistent misfire, even after changing plugs and wires. Does the misfire get worse or better as you apply the throttle?
Click to expand...
The more gas i give it the more it seems to misfire/struggle, at lower speeds -45 mph it runs pretty good as long as i don't hammer the gas but at speeds 50+ it really struggles and shutters and shakes and it has a really hard time going highway speeds. I cleaned the MAF a while ago and its not throwing a code so i pretty much ruled that out
 
M-Piers97 said:
The more gas i give it the more it seems to misfire/struggle, at lower speeds -45 mph it runs pretty good as long as i don't hammer the gas but at speeds 50+ it really struggles and shutters and shakes and it has a really hard time going highway speeds. I cleaned the MAF a while ago and its not throwing a code so i pretty much ruled that out
Click to expand...

My money is on the injector.
 
First, stop driving it. If it is misfiring like you describe you're going to either burn a valve or a piston or both. You've been driving it like this since September? You might be F'd already.

Provided you're not, and you're sure you have good plugs and wires, switch around your eBay coils and see if the code goes to a different cylinder. (FYI, there's a reason eBay parts are so much cheaper than OEM)

If the code follows the coil pack, you've found you're problem. If it doesn't, pull all the plugs and compression test the engine. If compression is good, I'd lean towards injector too.

Rather than buy an aftermarket injector, pull all 6 of yours and send them out to Witchhunter. Better to get all of your OEM injectors up to par rather than mess around with more aftermarket parts.
 
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PitbullRescuer said:
First, stop driving it. If it is misfiring like you describe you're going to either burn a valve or a piston or both. You've been driving it like this since September? You might be F'd already.

Provided you're not, and you're sure you have good plugs and wires, switch around your eBay coils and see if the code goes to a different cylinder. (FYI, there's a reason eBay parts are so much cheaper than OEM)

If the code follows the coil pack, you've found you're problem. If it does, pull all the plugs and compression test the engine. If compression is good, I'd lean towards injector too.

Rather than buy an aftermarket injector, pull all 6 of yours and send them out to Witchhunter. Better to get all of your OEM injectors up to par rather than mess around with more aftermarket parts.
Click to expand...


Beat me to it. That would be my advice, send em to Witchhunter.
 
I appreciate all of your help, but as for sending the injectors of to witchhunter to be cleaned is unpractical for me at this point. I understand ebay parts are a gamble but i am storing the vehicle outside and there is 3 feet of snow on the ground so i dont have a good place to tare apart the thing, i am really considering ordering the injector of ebay and having a local mechanic install it for me. Again i understand the better option would be to have it compression tested and the injector sent off to be cleaned but i am am a high school kid with a vary limited budget so i am going to cheapest route that gets it done.

Here is the ebay injectors
1 Year Warranty Genuine Denso Injector 92 98 Toyota 3 0 3 4 | eBay

1 Year Warranty 3 0L 3 4L V6 4Runner T100 Genuine Denso Single Fuel Injector | eBay
 
Is it safe to say that i can be 80% sure that its the #6 injector causing the misfire? also could running a sh!t load if injector cleaner through it get the thing to work again?
 
Witchhunter is $21/injector last time I used them. Turn time was a few days.

I understand being a high school kid on a budget, we've all been there. But that's all the more reason to do it right the first time. I would recommend you clean it off, find a friend with a compression tester and check it before you spend the money on anything else though. It probably is an injector, it's not uncommon especially at your mileage but better to be sure than to throw money & parts at it.
 
PitbullRescuer said:
Witchhunter is $21/injector last time I used them. Turn time was a few days.

I understand being a high school kid on a budget, we've all been there. But that's all the more reason to do it right the first time. I would recommend you clean it off, find a friend with a compression tester and check it before you spend the money on anything else though. It probably is an injector, it's not uncommon especially at your mileage but better to be sure than to throw money & parts at it.
Click to expand...

Yes i totally agree but like i said there is 3 feet of snow on the ground and i don't have a good place to work on it, i also went to witchhunters website and he cleans the injectors for $22 bucks apiece with a 4 day turnaround so one way or another i will be sending him my injector to be cleaned and i will also look into compression testing. Again thanks for all the help
 
If all else fails, do a compression test on all cylinders, followed by a leak down test (to insure there is no valve damage).
 
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