Re: Engine Knocking (4-cyl engine)
AllenCW said:
When I hit the gas very softly to go from 0 mph to 10 mph, the engine starts knocking a little. When I hit the gas very softly to go from 25mph to 35mph the engine starts knocking little. I have the 4 cyl with about 1,200 miles. Does anyone else have this problem? Or, what would you do in my case?
New member here, just joined today.
We got a 2LT 4cyl. 'Nox in November. The vehicle has 3700 mi. on it, it's my wife's daily driver.
At around the 3500 mi. mark she said she started to hear some spark knock. It wasn't harsh but there. I'm quite sensitive to such things (the engineer's curse,I guess), and sure enough it was light spark knock. It would happen in city driving, especially with the AC on, in about the same conditions you describe. I had it in the dealer yesterday to check it out since I was taking it in anyways for the HVAC software update and evap. canister campaign. The tech found nothing but the problem has gotten better in the last week. It was cool yesterday and the problem doesn't show up in cooler weather so it doesn't surprise me the tech found nothing right now.
I've asked on the GMinsidenews.com tech forum if anyone there had experienced this and no owners have seen it there. There are now two of us that have the issue, so it's something I'd wager is more common that I originally thought.
One thought on the other forum was the switch from winter to summer gasoline. That may explain why the problem is getting better in our 'Nox as the pinging is going away slowly by itself. I'll be back at the dealer if it keeps up, and since summer is coming it'll show up soon enough if indeed it's a problem. Don't be surprised if there's an ECM update to correct it in the future.
In the meantime, I'd suggest you take it to the dealer and see what they find. If you fill up with 92 octane it should never ever have spark knock. In our case, the car is running on 87 octane exclusively and the knock is very light.