Cylinder 3 Misfire

[PatrickStapler]

But your problem then shifted to 4. The odds of the injectors being bad on 3 and 4 are a lot less than the odds of the coil being bad for 3 and 4. I think you should start checking the input signal to the coil as you have pretty much ruled out the coil itself being bad.(three separate coils with the same problem are low odds) Swapping out another ecu is also another test you can do (they are pretty cheap used for the auto)

Assume this is a voltage check? What is it supposed to be?

 

[St Runner]

You are going to have to get the factory service manual for that question. Its a timed voltage so it would probably have to be tested through the OBD port. Swapping the ecu is a laymans way of checking it, but it also could be a short in the wiring harness. Normally if it stayed on one cylinder I would say injector, but as soon as it jumped to 4 all bets are off as to what it is. Might be worth it bringing it to someone with a good diagnostic computer who you trust

 

[octanejunkie]

Not knowing the age, mileage or service history of your truck, it's possibly prudent to consider refreshing all your injectors. You already said the coils were of unknown, non Toyota make, so it's possible the PO did the same with one or more injectors, or maybe it's just time for one or more to start failing.

Just putting that out there, but you should test them for resistance, and don't worry about pulling the TB/plenum, it's the pretty much the easiest part of the job, just time consuming.

BTW, when was the last time you replaced your fuel filter?

 

[PatrickStapler]

Not knowing the age, mileage or service history of your truck, it's possibly prudent to consider refreshing all your injectors. You already said the coils were of unknown, non Toyota make, so it's possible the PO did the same with one or more injectors, or maybe it's just time for one or more to start failing.

Just putting that out there, but you should test them for resistance, and don't worry about pulling the TB/plenum, it's the pretty much the easiest part of the job, just time consuming.

BTW, when was the last time you replaced your fuel filter?

Fuel filter is about a year old...new Toyota. The guy I purchased the car from paid for all maintenance to be done under his ownership. He did take decent care of the vehicle. He just apparently didn't specify Toyota specific parts.

 

[PatrickStapler]

So the part that is still confusing to me is I just drove home from work...approximately 20 minutes. Made one 10 minute stop. Not one single misfire. Ran perfect all the way home.

 

[PatrickStapler]

Drove the truck to the gym this morning...no misfires. One hour later, drove home from the gym...no misfires...and the CEL turned off.

Completely confused.

 

[PatrickStapler]

So after a few days of no misfires and no CEL, they're back. Now I have P0300, P0303, and P0304. Before I go ordering parts, is it possible the bad injector on 3 is causing the misfire on 4? I'm trying to decide if I need to order and replace two injectors or just the one on 3.

 

[spartacus]

So after a few days of no misfires and no CEL, they're back. Now I have P0300, P0303, and P0304. Before I go ordering parts, is it possible the bad injector on 3 is causing the misfire on 4? I'm trying to decide if I need to order and replace two injectors or just the one on 3.

you did the fuel injector treatment and now you have p0300,p0303 and p0304?
Its possible that p0303 causing p0300 and p0304.
First do the general maintenance stuff (fairly easy to do)
you've replaced , plugs, wires, coils with denso. Good there.
Clean Maf, replace if out of spec
check pcv valve and hose if not replaced in a while replace ( 15 dollars well spent)
check vacuum lines for cracks loose fittings dried up etc
check all connections battery terminal, camshaft connectors, ignitor wires etc, also check wires are good and grounds are good and tight.
clear the codes take it for a test drive and try and mimic the coditions that cause the misfire when you do get the misfire freeze frame the data. now check the codes and pending codes
you will probably end up with the codes again. replace injector on three.
Go from there.

 

[gamefreakgc]

Not really, you are just a lucky bum who happened to get multiple misfires. My bet is that if you keep driving the #3 code will pop up, along with the P0300 Multiple Misfire code.

So after a few days of no misfires and no CEL, they're back. Now I have P0300, P0303, and P0304. Before I go ordering parts, is it possible the bad injector on 3 is causing the misfire on 4? I'm trying to decide if I need to order and replace two injectors or just the one on 3.

Just have to say that I called it

P0300 is a useless code that just says you have misfires on more than one cylinder. The fuel injector can only provide fuel to one cylinder so can only cause a bad injector to throw one code. Before you buy injectors, like others said rule out everything else as a possible culprit. Also inspect the wiring to the injectors, I've seen these wires fray or be damaged from critters. My friend had one wire completely chewed off by rodents.

If you do replace injectors, replace with something like these:https://www.fiveomotorsport.com/23250-62030-tacoma-4run/. That's the 96-98 injector, don't know what year your 4Runner is so you might have the newer brown ones.

 

[PatrickStapler]

you did the fuel injector treatment and now you have p0300,p0303 and p0304?
Its possible that p0303 causing p0300 and p0304.
First do the general maintenance stuff (fairly easy to do)
you've replaced , plugs, wires, coils with denso. Good there.
Clean Maf, replace if out of spec
check pcv valve and hose if not replaced in a while replace ( 15 dollars well spent)
check vacuum lines for cracks loose fittings dried up etc
check all connections battery terminal, camshaft connectors, ignitor wires etc, also check wires are good and grounds are good and tight.
clear the codes take it for a test drive and try and mimic the coditions that cause the misfire when you do get the misfire freeze frame the data. now check the codes and pending codes
you will probably end up with the codes again. replace injector on three.
Go from there.

I think I have done everything in this list back in the Spring when I did the V/C gaskets and spark plug seals. Replaced the PCV valve and several suspect vacuum lines at the same time. Also just recently cleaned the MAF sensor because I thought it might be the culprit of this.

 

[PatrickStapler]

Just have to say that I called it

P0300 is a useless code that just says you have misfires on more than one cylinder. The fuel injector can only provide fuel to one cylinder so can only cause a bad injector to throw one code. Before you buy injectors, like others said rule out everything else as a possible culprit. Also inspect the wiring to the injectors, I've seen these wires fray or be damaged from critters. My friend had one wire completely chewed off by rodents.

If you do replace injectors, replace with something like these:https://www.fiveomotorsport.com/23250-62030-tacoma-4run/. That's the 96-98 injector, don't know what year your 4Runner is so you might have the newer brown ones.

I have note ran the voltage/gnd tests previously mentioned as of yet. Hope to try that this weekend. Truck is a '99. I believe the injectors are brown.

 

[Stiffmeister]

I recently had my truck stumbling and it turned out to be a coil pack. That was easy since you can just swap them around.

Now my only code is a P0330 just like yours. To figure out if it was a knock sensor (harness is new), I unplugged it up by the intake manifold. Used a hairclip/paperclip and crossed the connection. New code popped up as PO325 following which followed the probably bad knock sensor.

At least you can weed that out if you give it a shot. Unfortunately, if you can hear the misfire on a particular bank...well you're still in trouble. Following this post.

 

[PatrickStapler]

Ordered two new injectors and six insulators today...fingers crossed.

 

[PatrickStapler]

Replaced #3 and #4 injectors today. Cleaned the other 4 with throttle body cleaner. Replaced all the insulators. Replaced one o-ring on #5. Cleaned all the connectors with electrical contact cleaner. Cleaned the fuel rail with carb cleaner. Cleaned the throttle body.

Drove it a little today. Went through a couple heat cycles. No misfires so far. We’ll see how it goes from here.