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NEED HELP: Any suggestions! If you guys see something I missed in my troubleshooting process below, don't hesitate to call it out.
I do not have access to a higher end scanner/ OBD reader but will get one if its a must. I am at a loss as to why this fault keeps coming up.
2009 Chevy Cobalt LT 2.2L.
Problem:
P0304 (not intermittent, clear the code on a hot or cold engine. the fault pops back up within 5 seconds)
Fire:
1. New plugs(swapped them to to see if problem followed).
2. Good Solenoids (swapped them to to see if problem followed).
3. Visual inspect spark fire on all four plugs turning the motor over with them out and grounded, all seem the same.
Fuel:
1. Good fuel pressure (tested with gage)
2. Good Injectors (swapped them to to see if problem followed).
a. Also sprayed starter fluid while engine was running to verify the injectors were not leaking and sucking in air.
3. Screw driver listened to the injectors all sound same rhythm "ticking" pin pull injecting. ( to see if electrical pulse malfunction)
a. Also OHMed all injectors(reading same 12.5).
Air:
1. New MAF.
2. New MAP.
3. New Air Filter.
4. No cracks or leaks found with soapy water. And no codes for it.
5. Compression on all 4 cylinders is right at 200.
Misc:
1. New fuel filter.
2. New Vapor canister purge valve.
3. New Vent valve solenoid.
4. New Intake Solenoid Valve.
5. New Exhaust Solenoid Valve.
6. New Cam Shaft Position Sensor.
7. Car idles steady at 800rpm. No flutter.
8. Motor sounds a little rough (some mild ticking)when in gear and stopped at a light or stop sign. But the rpm is steady not fluttering still steady 800rpm. Goes away as soon as I let off the brake and car rolls.
9. Seafoamed the intake.
10. Seafoamed the gas tank.
11. Purged motor oil on last change(when I bought the car)
Last edited by JohnSmith321; Apr 1, 2021 at 05:57 AM.
What kind of ticking? Exhaust leak ticking... valvetrain ticking... or timing chain tensioner is bad ticking?
How many miles and have you changed the timing chain or timing chain tensioner?
Wouldn't think exhaust as that's more of a putting sound.
I was thinking the valvetrain.
No I have not changed the timing chain nor the tensioner. Could be the timing chain maybe. Would that make sense for it to do only when in drive or reverse while idling tension on chain that releases when you let off the brake?
And as for mileage lol 205k
When I clear code P0304 Cylinder #4 is firing at start up after code triggers it is not firing I can remove the electrical connection and no change in the now rough idle.
Also, New code P0106 now popping up and shutting car off I am testing the new and old MAP and MAF sensors now.....
this car is about to meet a .357 several times.
tired of part swapping this hunk of junk.
A very small exhaust leak at the manifold can make a ticking sound... especially if it's a cracked manifold (not all that uncommon for cast manifolds). I'd say this is the least likely option though.
Timing chain tensioner is a common failure and will cause a loud ticking... however, it usually it usually very loud, and when it first starts happening, it is loudest at first start up and gets quieter as oil pressure reaches it and stabilizes.
At 200k, it's probably advisable to have the timing chain, guides, and tensioner replaced. Some years are worse than others, others might chime in.
Bad MAP/MAF sensor typically will not affect only 1 cylinder... but these cars are weird sometimes and I certainly haven't seen everything they're capable of.
Internet diagnoses of small quirks is really hard.
Yes, I have a new fault code popping up as well now P0014 dealing with the timing. Already changed out the intake and exhaust cam position solenoid valve. Yes, I could pull it apart and change the camshaft phaser, completely clean out the entire motor to verify no trash or wear or broken mechanical components, pull the motor, pull the head etc, etc, etc...and still have same exact fault codes. I am kinda about done chasing my tail with this and plan on getting rid of the car or taking to someone with a high end scanner...feels like im treating all symptoms, not the root cause. I only changed all these parts because the compression is good and it leaks no oil, felt it does not hurt to change out the old parts even if not faulty, it is a worthy preventative measure once I did get it fixed...now the cost/effort is outweighing the total value of the car. My 92' berretta runs perfectly fine.
