2009 Vibe 2.4 pre-ignition spark knock

[tcp2150]

Bought this car new. Maintained it VERY well. 2.4 automatic. Hot Temps outside and regular fuel I am hearing clearly some spark knock or pinging under load at low speeds. If I hit the gas it stops. Doesn't do it at higher RPMS and does it a LOT less when I run premium fuel. I have tried:

1. GM upper end engine cleaner thinking carbon deposits. (Odd because most miles are highway).

2. Lucas additive to clean carbon deposits.

Never a check engine light. No codes in ECM. Car has 130k on it with ZERO problems. This will obliterate the engine if allowed to continue. There's no signs that knock sensor is out of spec or inoperable. ANYONE ELSE HAVE THIS HAPPEN??

[jolt]

If I hit the gas it stops.

This is just opposite of what would happen if you had spark knock or ping. I would guess you have something else going on with the motor.

[circuitsmith]

I think he means it pings at light throttle but stops if he goes to heavy throttle.

Does it last more than a second or two?
Light throttle pinging isn't as bad as at heavier throttle. Won't necessarily "obliterate the engine".
I remember lots of car doing lots of pinging back in the '70s.

I get a ping in hot weather that just lasts a split second, in the 2006 Matrix.

[tcp2150]

Test it's only under light throttle. Yes it only last for a second..... but now it's starting to do it with premium fuel too!! Creepy!! I wonder if it's running lean due to out of spec O2 sensor. Fuel pressure regulator?? It seems lean and therefore too hot up top. Fan coming on a LOT more than it used to.... Gauge shows cool but seems hot up top. Makes me wonder if there's a way to bleed air out of cooling system....

[circuitsmith]

O2 sensors typically go rich when they get too old.
Also, if the O2 sensor reading differs too much from what the MAF sensor, throttle position etc. says the fuel trim will be excessive and throw a code.
Low compression can raise temps due to low efficiency. Might be worthwhile to do a compression test.
Exhaust restriction is another possibility.

[cq358]

Does it occur when your a/c is on?

[dhart99]

Was there ever a resolution to this problem , just noticed ours is doing the same thing , no a/c is on either . thx

[jolt]

"Spark knock or pinging" is cause by two flame fronts burning in the combustion chamber. Normally there is just one flame front as the gas/air mixture is ignited by the spark plug. The shape of the combustion chamber can play a role in how the flame front travels but the biggest cause of pre-ignition is two things; low octane rating for fuel and combustion chamber deposits. Carbon deposits can cause hot spots that will per-ignite the fuel mixture causing the two flame fronts ( along with the spark plug) and make the noise. Have you changed the spark plugs? Did you use OEM brand spark plugs? How much carbon was on the spark plugs? Does the engine burn any motor oil? Unleaded fuel does not leave much for carbon deposits in a combustion chamber provided your using a high quality gasoline like Top Tier™ gasoline with higher levels of detergent. Motor oil will leave lots of carbon deposits behind. If your engine uses any motor oil, you will have carbon deposits in your combustion chamber.

3M made a kit to remove chamber deposits for fuel injected engines (now obsolete and cost ~$150.00) but most others of these types of kits involve feeding cleaner into a vacuum port on the intake manifold, which does not distribute the clean to all cylinders. Additives in the gas tank do little to nothing once the carbon is there but work well as a preventive measure. One do-it-yourself way I have seen is here:

http://www.fullsizechevy.com/forum/gene ... nique.html

Warning: performing the above is very dangerous and can lead to damaged paint, car fire, blown motor, etc...... make sure you know what you are getting into by doing this.

The best way to remove carbon is to pull the cylinder head off and physically clean the carbon out of the combustion chambers and the tops of the pistons; very expensive and time consuming.

A hot engine adds to the above by keeping the carbon hot and the low grade fuel burning before it should.

[dhart99]

As the OP mentioned the pinging happens at light throttle pressure . I can understand the increase in compression causing the pre ignition under heavy load or throttle but the ping goes away. I'm going to try octane booster additive to see if it settles down. . kinda surprised the knock sensor hasn't set a code or maybe it's not working. , BTW of course it uses oil