Cold Start Misfire - 2009 Pontiac Vibe

[nathaniel225]

2009 Pontiac Vibe - 1.8L engine (2ZR-FE)
I have unfortunately reached desperate measures but I am hoping someone may have a possible logical answer
Here is the story, when the car has been sitting for longer than 4 hours when the car is started it pretty much sounds like the engine is chocking, rpm will go to 1.5k then 1.1k then back to 1.5k, and so on for maybe three, or four times (Which is very abnormal since its never done that)
The check engine light gives a P0304 code, meaning it is a misfire in cylinder four, I have swapped the spark plugs, the misfire has not moved, I have swapped the ignition coil and the misfire has not changed position.
What is interesting is the engine started with a P0300 code and after two weeks it switched to a P0304 code and has been ONLY showing that code since then.
The MAF sensor has been cleaned too.
There is also a small engine rattle, which almost sounds like two utensils knocking on each other and the sound is repetitive faster ONLY when the throttle is applied and the sound is still apparent when the serpentine belt is removed too. When the car is idling the rattle is not there, and it will ONLY happen when the rpm is past 2.5k with throttle applied.
Engine oil and coolant levels are topped to the proper level, the engine does NOT burn coolant or oil!
Check engine light will turn on due to misfire on cold start but goes away when the engine warms up (after three start cycles or close to that) however will turn back on whenever the car misfires during the cold start (when it has been sitting longer than four hours)
To give further context, the outside temperature is -5 degrees Celsius, sorry my Americans ahaha anyway the colder it becomes the more apparent and severe the misfire is until the engine is warmed up then it seems to go away, or at least the engine stops jerking do not quote me on it.

UPDATE:
Replaced all four fuel injectors and the misfire still happens.
Compression test result (8 engine rotations from the starter):
Cylinder 1, 120 Psi
Cylinder 2, 118 Psi
Cylinder 3, 118 Psi
Cylinder 4, 114 Psi
I have uploaded a video of the cold startup on my channel: https://youtu.be/zaUiZacz20Q

[joatmon]

Welcome to genvibe

I don't know if the forum allows uploading a video, but since upload seems to have a small file size limit, it might not work even if it does allow videos. People seem to upload the video to youtube and then post a link here to it.

My first 03 had a problem that was not unique, and it seemed to be commonly referred to as idle hunting. When cold, the idle would swing regularly, as if someone was stepping on and releasing the gas pedal. There were a number of threads about it, one was viewtopic.php?p=399146#p399146 and also genviber stoutvibe has a youtube video showing the idle hunting at https://www.youtube.com/watch?v=Ev8ZUbN5f8s On mine it was finally resolved by replacing the intake manifold gasket. So far it seems like it's only been an issue on some of the 03-08s.

Don't know if that would cause your symptoms though

[jolt]

As joatmon said, it could be a small vacuum leak. As the engine warms and the parts expand, the leak seals up. Other thought are possible fuel injector leaking as it sits, and possible throttle body butterfly sticking. Make sure your throttle body is clean. What brand of spark plugs are you using? Have the coils been replaced? How many KM are on the Vibe?

[andrewclaus]

With the noise you describe, I wouldn't rule out a mechanical issue with a valve or piston. The cylinder misfire code doesn't care about the ignition--it's a mechanical sensor.

[nathaniel225]

Welcome to genvibe

I don't know if the forum allows uploading a video, but since upload seems to have a small file size limit, it might not work even if it does allow videos. People seem to upload the video to youtube and then post a link here to it.

My first 03 had a problem that was not unique, and it seemed to be commonly referred to as idle hunting. When cold, the idle would swing regularly, as if someone was stepping on and releasing the gas pedal. There were a number of threads about it, one was viewtopic.php?p=399146#p399146 and also genviber stoutvibe has a youtube video showing the idle hunting at https://www.youtube.com/watch?v=Ev8ZUbN5f8s On mine it was finally resolved by replacing the intake manifold gasket. So far it seems like it's only been an issue on some of the 03-08s.

Don't know if that would cause your symptoms though

Hey, I posted a video of it on my YouTube Channel, here is the link to it: https://youtu.be/zaUiZacz20Q I did a compression test, cylinder 1 120Psi, Cylinder 2 118 Psi, Cylinder 3 118 Psi, Cylinder 4 114 Psi. I replaced all four fuel injectors yet the car still misfires on cylinder four during the same scenarios :/

[nathaniel225]

With the noise you describe, I wouldn't rule out a mechanical issue with a valve or piston. The cylinder misfire code doesn't care about the ignition--it's a mechanical sensor.

Here I have attached a link to a video of my car starting when the misfire happens, let me know your thoughts! https://youtu.be/zaUiZacz20Q

[nathaniel225]

As joatmon said, it could be a small vacuum leak. As the engine warms and the parts expand, the leak seals up. Other thought are possible fuel injector leaking as it sits, and possible throttle body butterfly sticking. Make sure your throttle body is clean. What brand of spark plugs are you using? Have the coils been replaced? How many KM are on the Vibe?

NGK Iridium Spark Plugs
I have swapped coils around and the misfire did not change unfortunately.
240 000km on the engine.
I have not checked the electronic throttle body, so it will be something I will give it a look at.
I have also replaced all four fuel injectors and nothing changed, did a compression test, and here were the results:
Cylinder 1, 120 Psi
Cylinder 2, 118 Psi
Cylinder 3, 118 Psi
Cylinder 4, 114 Psi
Here is a link to the cold startup misfire video, I published it on my YouTube channel so anyone could see and hear it: https://youtu.be/zaUiZacz20Q

[jolt]

Here is the list:

Code P0304 Toyota Possible Causes

• Intake air leak

• Faulty spark plug #4

• Faulty ignition coil #4

• Clogged or faulty fuel injector #4

• Fuel injectors #4 harness is open or shorted

• Fuel Injectors #4 circuit poor electrical connection

• Ignition coils #4 harness is open or shorted

• Ignition coils #4 circuit poor electrical connection

• Incorrect Fuel pressure

• Faulty Mass Air Flow (MAF) Sensor

• Faulty Engine Control Module (ECM)

• Faulty Engine Coolant Temperature (ECT) Sensor

The spark plugs and coils are off the list as you have moved these around and the problem is still at #4 cylinder. If the fuel injector have been moved then that would also be off the list as long as the seals are good on the injectors. You still have vacuum leak possible, wiring issue possible on the coils and/or fuel injectors. Fuel pressure issues possible. Coolant temp sensor? Some cars have two temp sensors, one for the temp gauge, and the other for the ECM. I am not sure if the Vibe has two as I have never had a problem with my temp. With that many km on it things are going to be worn out. The compression on the cylinders is with in 10% of each other so that is not an issue that would cause rough idle.

Is coolant level to the top? Air trapped in the engine can easily happen with the Vibe, as this can cause the temp readings to be wrong. You could also have the beginning of a head gasket leak on cylinder #4. You could try a pressure test on the cooling system over night and see if the pressure drops. It could push coolant into the cylinder as the engine sits and then when you start the engine, it misfires until the coolant is burned out of the cylinder and things warm up. Also a combustion gas leak test to see if combustion gases are getting into the cooling system can be a sign of a leaking head gasket or cracked head. The overflow coolant tank should by clean with pink coolant in it. If brown is found in this tank, it could also be a sign that combustion is leaking into the cooling system.

[andrewclaus]

That engine knock might be a connecting rod bearing. Check out other videos, see what you think.

The misfire code is initiated by the crankshaft position sensor. If it senses a variation in shaft speed by more than a percent or two, and it's in one position consistently, it'll put out the code. Since your compression test shows a misbalance of more than one percent, I don't think it rules out a mechanical issue. This is all theory--I don't have any practical experience with fixing it myself.

[jolt]

That engine knock might be a connecting rod bearing. Check out other videos, see what you think.

The misfire code is initiated by the crankshaft position sensor. If it senses a variation in shaft speed by more than a percent or two, and it's in one position consistently, it'll put out the code. Since your compression test shows a misbalance of more than one percent, I don't think it rules out a mechanical issue. This is all theory--I don't have any practical experience with fixing it myself.

A connecting rod bearing failure noise will get quiet when under power or accelerating, and get loud when you take your foot off the gas pedal. The loose and bad bearing will tighten up under power and the noise goes away. This is why you will see a race cars engine blow when entering a corner and rarely does an engine come apart when exiting a corner. With that many km on the engine, you know that the timing chain and chain guide rails are shot and chain could be hitting.

[joatmon]

With that many km on the engine, you know that the timing chain and chain guide rails are shot and chain could be hitting.

I only had 1ZZs, are timing chains problematic in the 2ZRs?

[jolt]

I only had 1ZZs, are timing chains problematic in the 2ZRs?

Problematic, no. I must admit that i was thinking of the 2.4L with the counter balance shafts and chain that has a spring loaded tensioner for that chain. Anyways, chains do wear along with the guides, and the tensioner can only take up so much play.