Troubleshooting 3rd Gen 3.4 Misfire Code

Taco Man in HD

Taco Man in HD

New member
I know there are lots of misfire threads, but this one is driving me crazy. I recently purchased a '96 with 167k that had beem sitting for a few months. Ran fine, and just had an O2 sensor code previously and just started getting a Cylinder 3 misfire code from the CEL.

So far, I've replaced plugs, wires, injector, swapped coil packs, and ran injector cleaner through some gas, seafoamed, and still get the cylinder 3 code after a couple of resets. :dizzy:

Anyone have any other ideas before I drop some more cash to have a shop check it out? Any ideas are appreciated! Thanks!
 
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Taco Man in HD said:
I know there are lots of misfire threads, but this one is driving me crazy. I recently purchased a '96 with 167k that had beem sitting for a few months. Ran fine, and just had an O2 sensor code previously and just started getting a Cylinder 3 misfire code from the CEL.

So far, I've replaced plugs, wires, injector, swapped coil packs, and ran injector cleaner through some gas, seafoamed, and still get the cylinder 3 code after a couple of resets. :dizzy:

Anyone have any other ideas before I drop some more cash to have a shop check it out? Any ideas are appreciated! Thanks!
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What code are you getting, and did you replace the o2 sensor? You could also have a faulty injector that is leaking
 
I chased this situation once ? Ended up having all 6 injectors rebuilt at Conestoga diesel in Lancaster pa, this truck sat for 2 years then I ran injector cleaner thru fuel system then injector fail/miss chased it around till I just did all 6 problem solved.thinking that fuel cleaner rinsed crap out of fuel tank that screwed injectors
 
Kanger328 said:
I have a similar cylinder #3 misfire. Did all the steps you mentioned. Now my engine runs fine, but the misfire returns every few months and I have to replace the plug. I'm pretty sure my issue is a small HG leak...compression test won't detect.

Try letting your car sit for about 3-4 days, then start it up. If you see white smoke coming out of the exhaust that smells like a burned sweetness (if that makes sense), it's prob a HG leak. That's how I figured out mine.
Click to expand...

Or you can just look at your coolant reservoir. If you'r coolant is missing, it's going somewhere. You'll be able to notice this after one day of driving.
 
Before you start swapping injectors at least do a compression test. Most shops will do this for $50 - $100. Be sure to write the #s down and post them.
 
Thanks for all of the replies. The code is always P0303, and the O2 sensor code comes up after driving it for a while.

I installed the injector myself, coolant level is ok, and I've wondered about the HG or valve cover gasket too. Waiting on O2 sensor to arrive, but not hopeful that it would have any effect on the misfire. Gonna try to let it sit a while to check for any smoke or smells, like [MENTION=70513]Kanger328[/MENTION] recommended too.

I'm new to tracking down engine problems (none yet with my tacoma's 2.7 at 196k), but slowly isolating it with all of your guys' help!

Appreciate it!
 
Hey guys, had some time to tinker with the t4r before work...

The engine dies if I unplug the wires going to the coil pack, and the engine runs exactly the same if I unplug the wires going to the #3 injector.

The wires going to the injector are reading about .45 volts when it's running.

Not sure if any of this helps, but hoping to have it compression tested and further diagnosed at a shop sometime next week. :shrug:
 
Did you ever find a solution? I'm having a similar issue and we can't track it down. Cylinder 3 misfire...changed fuel filter, plugs, wires, coils, fuel injector...still shakes like crap, though intermittently. I'm stumped, mechanic is stumped. My brother-in-law runs a Toyota dealership so waiting on some feedback from their service department. I'm in Ohio, dealership is in Minnesota, unfortunately.
 
MyFirstRunner said:
Did you ever find a solution? I'm having a similar issue and we can't track it down. Cylinder 3 misfire...changed fuel filter, plugs, wires, coils, fuel injector...still shakes like crap, though intermittently. I'm stumped, mechanic is stumped. My brother-in-law runs a Toyota dealership so waiting on some feedback from their service department. I'm in Ohio, dealership is in Minnesota, unfortunately.
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Compression test results?
 
Compression was good. My mechanic just called me and the re-manufactured injector I got from Rock Auto turned out to be bad. He tested the resistance and it was like 50 while all the other were around 14. SOAB. Going to get a 3rd injector and put it in on Monday...fingers crossed.
 
MyFirstRunner said:
Compression was good. My mechanic just called me and the re-manufactured injector I got from Rock Auto turned out to be bad. He tested the resistance and it was like 50 while all the other were around 14. SOAB. Going to get a 3rd injector and put it in on Monday...fingers crossed.
Click to expand...

This is surprisingly common. It you are swapping a single suspect injector, it's a good idea to move a known good one from a different spark circuit to replace the bad one, and put the new one where the first one came from. That way you know if the new one is bad.
 
I think my error was telling my mechanic I swapped the injector, he probably would have checked the resistance on the first day. Oh well, live and learn.
 
I had a misfire problem at high RPM. I replaced the coil pack boots and it solved the problem.

More Information for DENSO 6716248

These can go bad and lead to arcing between the wires and the engine head versus sending the current through the plug.

Could also be the valve cover gaskets or the camshaft plugs leaking oil.
 
Cylinders 1 & 4 - Misfire & Mystery

1999 4R Limited, 330k on the clock. Overall good shape. Short drive to store, enough to get it warm. Come back out, start it up, and it's missing. Limp it home and get flashing CEL.

Pull codes and it's 0300, 0301, 0304. The latter 2 indicate cyl's 1 and 4 are misfiring. Cool, they both share the same coil, replace that and I'm golden, right? That's gotta be it, right?

Nope. Replaced coil at Cyl 1 [which also feeds Cyl 4] and it does the same thing. Pull the codes, same codes. Just for grins I swap coils with Cyl 5 and the miss stays with Cyl's 1&4. Crap. Problem upstream of the Cyl1/4 coil?

For no particular reason then, I change all 3 plug wires and the plugs from 1&4. The old plugs looked fine... Test drove it and... you guessed it. Same bloody thing. Runs fine at start-up, drive it a ways, turn it off then back on and BAM dead miss and same OBDII codes.

Having a hard time thinking I have two injectors failing at same time, but I recreated the misfire state, yanked the Cyl#1 plug, grounded that sucker, and turned the motor over. Much to my surprise, I did have spark... That suggests to me that it is a fuel problem, most likely an injector -- or two. I didn't check for spark on Cyl 4, but spark on Cyl 1 blows my Cyl1&4 upstream voltage theory...

Looks like there's no easy way to swap injectors around to see if the problem moves with it. If I have to take the time to yank the plenum off I may as well change those two injectors -- or all of them.

Does this sound reasonable? Anybody know if a good pro diagnostic machine could bird-dog a misfire, ie differentiate between an injector and an ignitor? Might be worth [shudder] taking it somewhere...

I'm hoping one of you mechanical geniuses out there can shine some light on this mystery... My thanks in advance!
 
did this all start suddenly, like one day ? I find it hard that two injectors go bad as same time. Anything is possible
 
imjustdad said:
1999 4R Limited, 330k on the clock. Overall good shape. Short drive to store, enough to get it warm. Come back out, start it up, and it's missing. Limp it home and get flashing CEL.

Pull codes and it's 0300, 0301, 0304. The latter 2 indicate cyl's 1 and 4 are misfiring. Cool, they both share the same coil, replace that and I'm golden, right? That's gotta be it, right?

Nope. Replaced coil at Cyl 1 [which also feeds Cyl 4] and it does the same thing. Pull the codes, same codes. Just for grins I swap coils with Cyl 5 and the miss stays with Cyl's 1&4. Crap. Problem upstream of the Cyl1/4 coil?

For no particular reason then, I change all 3 plug wires and the plugs from 1&4. The old plugs looked fine... Test drove it and... you guessed it. Same bloody thing. Runs fine at start-up, drive it a ways, turn it off then back on and BAM dead miss and same OBDII codes.

Having a hard time thinking I have two injectors failing at same time, but I recreated the misfire state, yanked the Cyl#1 plug, grounded that sucker, and turned the motor over. Much to my surprise, I did have spark... That suggests to me that it is a fuel problem, most likely an injector -- or two. I didn't check for spark on Cyl 4, but spark on Cyl 1 blows my Cyl1&4 upstream voltage theory...

Looks like there's no easy way to swap injectors around to see if the problem moves with it. If I have to take the time to yank the plenum off I may as well change those two injectors -- or all of them.

Does this sound reasonable? Anybody know if a good pro diagnostic machine could bird-dog a misfire, ie differentiate between an injector and an ignitor? Might be worth [shudder] taking it somewhere...

I'm hoping one of you mechanical geniuses out there can shine some light on this mystery... My thanks in advance!
Click to expand...

If you have spark in one then check the #1 injector. (is easy to get to) it should be 13 to 13.6 ohms cold and higher like 16 ohms when hot. if the injectors are good then do a compression test to rule out the head gasket.
 
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