1999 Limited 4wd 3.4 4Runner. Stopped to get gas truck was running on fumes. Drove to friend house on was home truck starting hesitating shaking rough riding almost stalling at stop signs had to put in neutral to keep running but able to limp it home. Checked with Actron AutoScanner Plus with code connect. Code P0304 cylinder 4 misfire detected. Completed most of the frequent reported fixes that Code connect suggested. Replaced plugs and wires NGK, all 3 Ignition Coils(OEM) fuel filter, throttle position sensor (OEM) cleaned throttle body and mass air flow. Cranked right up check eng light off, Took for short drive around block ran ok. Then took for longer drive and it started all over again. Check eng light flashing hesitating and shaking. When I let off gas hesitation slows but when accelerate starts back hesitating, almost stalling at stops had to put in neutral to keep running running very rough again. It's like I did nothing to it. Checked code same P0304 cylinder 4 misfire. Any suggestion would help very low on funds after all the parts
Please help Code P0304 at wits end
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delloro
New member
Check your injector. If the exhaust does not smell like partially burnt fuel, then the injector is not working. Use a mechanics stethoscope on the injector to listen for the clicking. If no clicking noise, the injector is not working. check the injector plug for signal.
If the exhaust does smell like partially burnt fuel, then the injector is stuck open to some degree.
If the exhaust does smell like partially burnt fuel, then the injector is stuck open to some degree.
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1moreToy4me
New member
Anything?
It smells a little like fuel. You said check the injector plug- with a ohms meter. Not sure. I am a shade tree mechanic so not worked much with meter. Can you explain. Ordered a new injected going to attempt to install next weekend. Any helpful advise when replacing injectors. Any new gaskets I might have to replace?
delloro
New member
Ohm meter may not help. Disconnect the wiring from the injector and see what ohm reading you have across the injector terminals. Wide open means the injector is bad.
Put a mechanic's stethoscope on the injector and see if it makes a clicking sound, like it is supposed to. No clicking means it is not working.
BUT if it is running rich at idle and missing, and you are getting a single-cylinder misfire code, your injector might bring stuck open a little. If that is the case, the ohms reading is probably within spec and it is probably clicking too. Replacing injector is probably the most direct way to address.
Put a mechanic's stethoscope on the injector and see if it makes a clicking sound, like it is supposed to. No clicking means it is not working.
BUT if it is running rich at idle and missing, and you are getting a single-cylinder misfire code, your injector might bring stuck open a little. If that is the case, the ohms reading is probably within spec and it is probably clicking too. Replacing injector is probably the most direct way to address.
jackrabbit66
New member
Check the following
From easiest to hardest Id suggest looking at the following:
1. Check the fuel pump. When you start the car after its been sitting for a few hours you will hear a hum from the fuel pump. Its usually a steady hum for a few seconds. If you have a failing fuel pump it will sound rough, change pitch, and take longer to reach the correct pressure. You can also check the fuel pressure with a fuel pressure gauge. If you have lower than spec fuel pressure while having the problems with your engine, you may need a new fuel pump.
2. check for vacuum leaks. If you hear a sucking sound inside your engine compartment or a loud whistling, check for vacuum leaks. take some carb cleaner and spray it around the air intake manifold and all the vacuum lines / hoses connected to the engine. if the spraying in a particular area causes the car to stutter or surge then you have a vacuum leak in that area.
3. check the spark plug for discoloration. If you search online for "spark plug diagnosis" you will find a diagram of different spark plug conditions. This could lead you to the solution.
4. Switch the Coil packs. If your having trouble with your #4 cylinder then switch the #4 coil pack with a different one and see if the problem follows the coil pack to a different cylinder.
4. check for cylinder compression. If you can, check the compression of each cylinder with a compression gauge. With the Fuel pump relay removed, remove the spark plugs one at a time and check the compression of all the cylinders. If you have low compression in #4 cylinder you probably have a bad head gasket.
also check to see if you have bubbles coming out of your radiator or white goo. When the engine is cold remove the radiator cap and look at the inside of the cap. if you have a white goo, that may mean you have oil in your coolant system caused by a bad head gasket. With the radiator cap off, start the engine and see if you get bubbles or a guiser of coolant coming out of the radiator. If you do...replace the head gasket.
6. check the Fuel injector. This can be difficult because you have to take off the air intake manifold and fuel rail on most cases. But its really not as hard as it sounds. With the fuel rail still on you can remove the electrical connectors to the fuel injectors and check the resistance / ohms between the two contacts. The resistance / ohmes should read pretty much the same for all injectors. on my 4L 2005 4runner the resistance for each injector is around 12.2 ohmes.
From easiest to hardest Id suggest looking at the following:
1. Check the fuel pump. When you start the car after its been sitting for a few hours you will hear a hum from the fuel pump. Its usually a steady hum for a few seconds. If you have a failing fuel pump it will sound rough, change pitch, and take longer to reach the correct pressure. You can also check the fuel pressure with a fuel pressure gauge. If you have lower than spec fuel pressure while having the problems with your engine, you may need a new fuel pump.
2. check for vacuum leaks. If you hear a sucking sound inside your engine compartment or a loud whistling, check for vacuum leaks. take some carb cleaner and spray it around the air intake manifold and all the vacuum lines / hoses connected to the engine. if the spraying in a particular area causes the car to stutter or surge then you have a vacuum leak in that area.
3. check the spark plug for discoloration. If you search online for "spark plug diagnosis" you will find a diagram of different spark plug conditions. This could lead you to the solution.
4. Switch the Coil packs. If your having trouble with your #4 cylinder then switch the #4 coil pack with a different one and see if the problem follows the coil pack to a different cylinder.
4. check for cylinder compression. If you can, check the compression of each cylinder with a compression gauge. With the Fuel pump relay removed, remove the spark plugs one at a time and check the compression of all the cylinders. If you have low compression in #4 cylinder you probably have a bad head gasket.
also check to see if you have bubbles coming out of your radiator or white goo. When the engine is cold remove the radiator cap and look at the inside of the cap. if you have a white goo, that may mean you have oil in your coolant system caused by a bad head gasket. With the radiator cap off, start the engine and see if you get bubbles or a guiser of coolant coming out of the radiator. If you do...replace the head gasket.
6. check the Fuel injector. This can be difficult because you have to take off the air intake manifold and fuel rail on most cases. But its really not as hard as it sounds. With the fuel rail still on you can remove the electrical connectors to the fuel injectors and check the resistance / ohms between the two contacts. The resistance / ohmes should read pretty much the same for all injectors. on my 4L 2005 4runner the resistance for each injector is around 12.2 ohmes.
mini kahuna
New member
flashing check engine light can mean cat converter damage will/is occurring, I would lean towards the posts with #4 injector hanging open.
spark plug on #4 will look fouled out as another clue to injector leaking or stuck part way open.
low compression wouldn't come and go like that
spark plug on #4 will look fouled out as another clue to injector leaking or stuck part way open.
low compression wouldn't come and go like that
98RunnerLazarus
New member
My cylinder 2 misfire was a bad injector
Thanks to everyone in these forums for helping me solve a cylinder 2 misfire that would come and go when I had just hit 199k in my 98 Toyota 4Runner 2.7L. Basically I had a check engine light come on from time to time that seemed to progress into a few horrible misfires, especially when punching it up to 70mph on the highway. It's a horrible feeling as you're experiencing a blinking check engine light and your 4Runner shaking so violently that you just want to get it off the road as quickly as possible.
After the first violent misfire I immediately got a full diagnostic check in which my 4Runner passed with flying colors. (Spark plugs looked fine, swapping coil packs had no effect, plugs and wires had been changed 2 1/2 years ago and I had only drove about 18,000 miles since then). I was only charged $30 rather than the standard $110 because the mechanic couldn't figure out the issue. The mechanic referred me to an engine shop. I immediately thought of a leaking or blown head gasket but it wasn't showing any of those symptoms. I refused to go to an engine shop.
I seafoamed the fuel tank and motor, added some fuel injector cleaner to the gas tank, filled it completely with 93 octane fuel, and then drove it for 100 miles before changing the oil with no issues or a CEL coming on. Then at 110 miles, while on the highway, BAM...vehicle began shaking and CEL was blinking. I immediately pulled over and had it towed to a Dealership (Stealership). I had enough playing around with the 4Runner and wanted it fixed.
I constantly searched the internet and this website with issues similar to mine. All signs pointed to a bad fuel injector. I requested they immediately swap injector 2 with injector 1. The misfire had always been with cylinder 2. If the misfire moved to cylinder 1 then it was most likely a bad injector. After test driving it about 10 miles the misfire came back as violent as ever. I had the dealership immediately check the code and the misfire had moved to cylinder 1. I had an OEM injector installed and haven't had an issue in the past 2,000 miles. I nicknamed the 4Runner Lazarus because i feel it rose from the dead.
Thanks again to everyone who posts their issues and their solutions in this site.
Thanks to everyone in these forums for helping me solve a cylinder 2 misfire that would come and go when I had just hit 199k in my 98 Toyota 4Runner 2.7L. Basically I had a check engine light come on from time to time that seemed to progress into a few horrible misfires, especially when punching it up to 70mph on the highway. It's a horrible feeling as you're experiencing a blinking check engine light and your 4Runner shaking so violently that you just want to get it off the road as quickly as possible.
After the first violent misfire I immediately got a full diagnostic check in which my 4Runner passed with flying colors. (Spark plugs looked fine, swapping coil packs had no effect, plugs and wires had been changed 2 1/2 years ago and I had only drove about 18,000 miles since then). I was only charged $30 rather than the standard $110 because the mechanic couldn't figure out the issue. The mechanic referred me to an engine shop. I immediately thought of a leaking or blown head gasket but it wasn't showing any of those symptoms. I refused to go to an engine shop.
I seafoamed the fuel tank and motor, added some fuel injector cleaner to the gas tank, filled it completely with 93 octane fuel, and then drove it for 100 miles before changing the oil with no issues or a CEL coming on. Then at 110 miles, while on the highway, BAM...vehicle began shaking and CEL was blinking. I immediately pulled over and had it towed to a Dealership (Stealership). I had enough playing around with the 4Runner and wanted it fixed.
I constantly searched the internet and this website with issues similar to mine. All signs pointed to a bad fuel injector. I requested they immediately swap injector 2 with injector 1. The misfire had always been with cylinder 2. If the misfire moved to cylinder 1 then it was most likely a bad injector. After test driving it about 10 miles the misfire came back as violent as ever. I had the dealership immediately check the code and the misfire had moved to cylinder 1. I had an OEM injector installed and haven't had an issue in the past 2,000 miles. I nicknamed the 4Runner Lazarus because i feel it rose from the dead.
Thanks again to everyone who posts their issues and their solutions in this site.
