1998 3rz #4 continues to misfire, tried everything Please Help?

[VincentGsrq]

Hello,
My 1998 3rz 2wd auto with 255k two weeks ago started to misfire number 4 and cel came on, often blinking sometimes continuous, runs rough, sputters, low idle in gear, better in neutral, it will start and run and drive, zero power until over 2500rpm. My scanner continues to show only cylinder 4 misfiring after doing the following;

cleaned the maf
swapped coils, coils plugs and wires are less than 40k old
compression check 142 145 145 152 new tri electrode plugs installed
all plug wire resistance nominal spec
injector resistance all within spec
removed fuel rail, replaced gaskets and seals on all 4 and swapped #2 and 4
injector locations
today I swapped out the ECU with a used unit that arrived

Still #4 misfiring, no other codes thrown

Any advice or suggestion would be greatly appreciated. My next step at this point is an AD diag.

Thank you in advance,
Vince

 

[Hokie-Pokie VT]

Hi Vincent,

We all know wires shouldn't go bad after 40k miles, but I think you should try the following before going any deeper. Compression test indicates good news that you aren't likely looking at anything catastrophic in the engine. The only thing I would think is that your catalytic converter has gone bad. Sometimes when they go, they can foul a coil pack or a plug due to back pressure.

I would:

- Remove coil pack on Cyl 1. and check the plug for that the wire that goes to Cyl. 4. You should see the copper contacts, if they appear dirty or black, clean them. Do the same with both ends of the wire, ensure that the metal inside of the plastic cap that connects to the coil pack is clean and not bent. inspect inside the rubber tube that goes down into Cyl 4 and make sure you can see the metal contacts that fit to the spark plug. If any of the contacts appear dirty, I use the WD-40 Electrical Contact Cleaner (https://www.wd40.com/products/conta...over 95,for optimal performance of equipment.). If all looks good, reassemble and ensure all connections are solid.

- If misfire persists, swap for another coil pack again, and repeat the inspection and cleaning of the wire connector for the coil pack.

- If misfire persists, I would start with new wires just because there're cheaper, and if the misfire doesn't move with the coil pack, then I would personally rule that out. Literally all 4R drivers I know use the NGK Blue's (https://shop.advanceautoparts.com/p/ngk-spark-plug-wire-set-4412/15500233-P). They're cheap and reliable.

I really would bet that your wire is bad. Lots of manufacturing defects are making it through to shelves as a result of COVID, suppliers are running short and they're letting more stuff through their QC.

Also a note, I don't think that 4Runners run tir-electrodes. Personally, I run single electrode, I get no worse fuel economy. Maybe 98's ran 3 electrode, but Im pretty sure that my 02 ran dual electrodes from the factory. Not that it really matters.

Best of luck. Hopefully its not the cat.

 

[Bad Luck]

Stop guessing and start diagnosing. Do a compression test on all 4 cylinders and post your results.

 

[VincentGsrq]

Stop guessing and start diagnosing. Do a compression test on all 4 cylinders and post your results.

I did a compression test and posted it above, in order

142 145 145 152

I installed the new tri electrode plugs after the compression test

 

[VincentGsrq]

Hi Vincent,

We all know wires shouldn't go bad after 40k miles, but I think you should try the following before going any deeper. Compression test indicates good news that you aren't likely looking at anything catastrophic in the engine. The only thing I would think is that your catalytic converter has gone bad. Sometimes when they go, they can foul a coil pack or a plug due to back pressure.

I would:

- Remove coil pack on Cyl 1. and check the plug for that the wire that goes to Cyl. 4. You should see the copper contacts, if they appear dirty or black, clean them. Do the same with both ends of the wire, ensure that the metal inside of the plastic cap that connects to the coil pack is clean and not bent. inspect inside the rubber tube that goes down into Cyl 4 and make sure you can see the metal contacts that fit to the spark plug. If any of the contacts appear dirty, I use the WD-40 Electrical Contact Cleaner (https://www.wd40.com/products/conta...over 95,for optimal performance of equipment.). If all looks good, reassemble and ensure all connections are solid.

- If misfire persists, swap for another coil pack again, and repeat the inspection and cleaning of the wire connector for the coil pack.

- If misfire persists, I would start with new wires just because there're cheaper, and if the misfire doesn't move with the coil pack, then I would personally rule that out. Literally all 4R drivers I know use the NGK Blue's (https://shop.advanceautoparts.com/p/ngk-spark-plug-wire-set-4412/15500233-P). They're cheap and reliable.

I really would bet that your wire is bad. Lots of manufacturing defects are making it through to shelves as a result of COVID, suppliers are running short and they're letting more stuff through their QC.

Also a note, I don't think that 4Runners run tir-electrodes. Personally, I run single electrode, I get no worse fuel economy. Maybe 98's ran 3 electrode, but Im pretty sure that my 02 ran dual electrodes from the factory. Not that it really matters.

Best of luck. Hopefully its not the cat.

I had planned to install dual electrode and chose the tri just cuz

A new set of wires is an easy try, none of the wire ends were discolored when the boot was retracted

here is a pic of the >40k plugs that were in before the compression check

 

[brillo_76]

I have in the past seen a coil test good and still misfire. So like the other suggested swap #4 with another cylinder. If the misfire follows its the coil. If it stays on cylinder 4 it's the plug or the wires that drive the coil. Or the injector on cylinder 4.


I would swap injector 4 with another as a test too. Keep in mind, an injector can test resistance properly and still be plugged..

You ever run any injector cleaner through the fuel system?

I don't suspect the ecu etc. Misfire is mostly no fuel or spark or head gasket etc.



Sent from my SM-A505U using Tapatalk

 

[St Runner]

I also agree with changing the wires. I had to do it every couple years when I owned a 3rz. Get a good quality set. You are running a 2 coil setup?

 

[VincentGsrq]

I have in the past seen a coil test good and still misfire. So like the other suggested swap #4 with another cylinder. If the misfire follows its the coil. If it stays on cylinder 4 it's the plug or the wires that drive the coil. Or the injector on cylinder 4.


I would swap injector 4 with another as a test too. Keep in mind, an injector can test resistance properly and still be plugged..

You ever run any injector cleaner through the fuel system?

I don't suspect the ecu etc. Misfire is mostly no fuel or spark or head gasket etc.

Both coils (under 40k old) are oem denso after swapping them the misfire stayed on number 4

Swapped injectors from number 4 and number 2, number 4 kept misfiring

I run Gas Shok fuel treatment

while injectors were out I cleaned them (spray) before installing new seals

 

[Bad Luck]

I did a compression test and posted it above, in order

142 145 145 152

I installed the new tri electrode plugs after the compression test

Must have missed that somehow. My apologies.

Have you verified that cylinder #4 is getting spark? Have you verified it's getting fuel?

 

[VincentGsrq]

Must have missed that somehow. My apologies.

Have you verified that cylinder #4 is getting spark? Have you verified it's getting fuel?

the plug looks wet with fuel, especially compared to the other, i swapped the coils and now I am thinking to throw a set of wires at it, also thinking of how to check that number four injector is getting a voltage pulse

 

[Bad Luck]

the plug looks wet with fuel, especially compared to the other, i swapped the coils and now I am thinking to throw a set of wires at it, also thinking of how to check that number four injector is getting a voltage pulse

I think you would need a noid light to verify the injector is pulsing and not just being powered/commanded on/flow the whole time.

Correct me if I'm wrong but you've verified/eliminated:
-Ecu
-Spark plug(s)
-Injector
-Coil
-Spark plug wires
-Compression

All that I can think of that's left to check is the wiring for the injector. If a noid light pulses for that injector (also compare to the other injectors) then that would lead me to believe the injector wiring circuit/control is operating as designed.

 

[VincentGsrq]

I think you would need a noid light to verify the injector is pulsing and not just being powered/commanded on/flow the whole time.

Correct me if I'm wrong but you've verified/eliminated:
-Ecu
-Spark plug(s)
-Injector
-Coil
-Spark plug wires
-Compression

All that I can think of that's left to check is the wiring for the injector. If a noid light pulses for that injector (also compare to the other injectors) then that would lead me to believe the injector wiring circuit/control is operating as designed.

I am going to try a noid light on injector number 4 lead, thank you

 

[VincentGsrq]

When I bought the noid light set I also bought a spark plug in line tester ($3.99) and modified with a piece of pvc tubing to get it to seat down on the plug. I had also pulled out the parts cannon and bought a set of "house brand" wires as well, I jumped across with the new number 4 plug wire hooked up with the inline test light and started her up, the light was flashing perfectly and the engine seemed to be smooth. I shut it down and replaced the number four plug wire with the new one and pulled out the test light, hooked up the scanner to live data and no more number four misfire, she is smooth as can be. A nice boxing day present, thank you lord.
My guess is that when I checked the 30k mi old wire in the very beginning when I swapped coils (also 30k mi old) it read 16.4 on the meter, fsm reads "under 25k ohms" I did not look to see the scale and if it was 16.4 "K", it may have been M or some other scale idk but I will def be checking the meter on that wire tomorrow
Thanks to everyone for their advice!
Very happy to be back on the road
Vince