2010 lx570 code po 304 UPDATE #2

[CanadianRockyCruiser]

Consider testing the injector before buying a new engine. If you have an ohmmeter you can test the injector by testing each electrical lead on it. Alternatively you can swap injector #4 with another injector, pull the battery negative cable for about 5 mins, then reattach the battery cable. In this way you can determine if it's an injector issue.

If not, P0304 can also arise due to:

1. Open or short in engine wire harness
2. Connector connection
3. Vacuum hose connections
4. Ignition system
5. Fuel injector assembly
6. Fuel pressure
7. Mass air flow meter assembly
8. Engine coolant temperature sensor
9. Compression pressure
10. Valve timing
11. PCV valve and hose
12. PCV hose connections
13. Air induction system
14. ECM
    
    (I know, that's a laundry list)

 

[TTO5]

Maybe a leaking injector? Getting them professionally cleaned will be a lot simpler/cheaper than swapping the engine.

For sure. I read a way to check for that is to watch fuel pressure after switching off engine. Should see no drop?

 

[TTO5]

Consider testing the injector before buying a new engine. If you have an ohmmeter you can test the injector by testing each electrical lead on it. Alternatively you can swap injector #4 with another injector, pull the battery negative cable for about 5 mins, then reattach the battery cable. In this way you can determine if it's an injector issue.

If not, P0304 can also arise due to:

1. Open or short in engine wire harness
2. Connector connection
3. Vacuum hose connections
4. Ignition system
5. Fuel injector assembly
6. Fuel pressure
7. Mass air flow meter assembly
8. Engine coolant temperature sensor
9. Compression pressure
10. Valve timing
11. PCV valve and hose
12. PCV hose connections
13. Air induction system
14. ECM
    
    (I know, that's a laundry list)

You think that wetness could be fuel?

 

[CanadianRockyCruiser]

You think that wetness could be fuel?

Possible. If you test the connectors 1 and 2 with multimeter leads you should get a reading between 11.6 and 12.4 Ohms. If not, replace the injector assembly.

Also check you PCV and PCV hose before getting too deep.

 

[marques]

For sure. I read a way to check for that is to watch fuel pressure after switching off engine. Should see no drop?

Fuel pressure could come down for any number of reasons, so that won’t be very conclusive. You could move the suspect injector to a different location and see if the problem moves with it. Or, considering the mileage, you could just send them all to be ultrasonically cleaned and flushed back to like-new condition.

 

[TTO5]

Possible. If you test the connectors 1 and 2 with multimeter leads you should get a reading between 11.6 and 12.4 Ohms. If not, replace the injector assembly.

Also check you PCV and PCV hose before getting too deep.

The ohm reading will point to a leaky injector?

 

[CanadianRockyCruiser]

The ohm reading will point to a leaky injector?

Ohm reading will let you know if it has the correct electrical resistance. If not it is likely faulty and should be replaced. You can also bench test the injector, if you take it out and hook up the injector to a bench fuel supply. It should flow 82 to 99 cm in 15 seconds of runtime...however, that is a messy and complicated procedure compared to an ohm test.

 

[TTO5]

Here's what I don't understand. This morning I started up the truck, mil on and flashing (can feel it misfiring). Drove about 1 mile, pulled over, shut engine off, counted 5 seconds, restarted it and mil solid not flashing smooth as can be (then drove 20 miles to work highway speeds up to 80 mph). Mil stayed on solid no misfire felt. Shut truck off for 20 min. Restarted, mil flashed for about 10 sec then went solid (all while idling)

 

[TTO5]

Ohm reading will let you know if it has the correct electrical resistance. If not it is likely faulty and should be replaced. You can also bench test the injector, if you take it out and hook up the injector to a bench fuel supply. It should flow 82 to 99 cm in 15 seconds of runtime...however, that is a messy and complicated procedure compared to an ohm test.

That test only tells me if the injector works? If it's leaking into the port will that be revealed in this test or do I need to physically pull the injectors and look for a leak?

 

[CanadianRockyCruiser]

That test only tells me if the injector works? If it's leaking into the port will that be revealed in this test or do I need to physically pull the injectors and look for a leak?

If it fails the test, it may keep the injector stuck "open", flowing fuel when it should not. If you have a multimeter, just test it. It takes minutes. Here is how you access it:

Check your injector "o" rings too.

 

[TTO5]

Thank you. I intend to do that test

 

[TTO5]

Anyone think this looks more like coolant than fuel? Hoping it's fuel. I would think the spark plug that was in there for 115 k miles would look cleaner though.

 

[grinchy]

You’re worried about a head gasket leak for coolant?
i used this tester.

 

[TTO5]

You’re worried about a head gasket leak for coolant?
i used this tester.

I'm not worried that exhaust is mixing with coolant. Is there a way to test the fluid found on the top of my piston to see if it's coolant?

 

[Malleus]

Send a sample of your oil to Blackstone.

 

[rherrco]

I'm not worried that exhaust is mixing with coolant. Is there a way to test the fluid found on the top of my piston to see if it's coolant?

I bet the car care nut could tell you what it is. My bet is coolant.

 

[TTO5]

I bet the car care nut could tell you what it is. My bet is coolant.

I'm hoping not. The spark plug would be cleaner and not all black fouled right?

 

[Zjohnsonua]

Are you losing coolant? That looks less viscous than oil, either fuel or water. Fuel and coolant smell and taste totally different than one another. - get that piston to the top and see if you can get a long q-tip to pick some up - then see what you've got. If it's too hard to get enough to tell, then move the injector and see what happens.

This plug has 180k on it. The other 7 look like this one. Yours is contaminated, given the darkness and kinda sooty look I'd lean towards fuel.

 

[TTO5]

Are you losing coolant? That looks less viscous than oil, either fuel or water. Fuel and coolant smell and taste totally different than one another. - get that piston to the top and see if you can get a long q-tip to pick some up - then see what you've got. If it's too hard to get enough to tell, then move the injector and see what happens.

This plug has 180k on it. The other 7 look like this one. Yours is contaminated, given the darkness and kinda sooty look I'd lean towards fuel.

View attachment 3730425

All good info I appreciate it. Is there any way to bump the motor without it starting? If I tap on the power button it'll crank till it starts. Purpose is to get the piston closer to the top. Trying to avoid pulling all 8 plugs so there is less resistance Trying to turn the engine by hand

 

[Sandroad]

All good info I appreciate it. Is there any way to bump the motor without it starting? If I tap on the power button it'll crank till it starts. Purpose is to get the piston closer to the top. Trying to avoid pulling all 8 plugs so there is less resistance Trying to turn the engine by hand

You can buy 8” cotton swaps on Amazon and if that’s not long enough, tape 2 together. Getting a sample of the liquid should tell you everything you need to know.