2008 p0340

[OG-Lou]

I re-gaped the old spark plugs that came with the car (when the engine was running perfectly) and still have the bucking (2 bucks) when I apply light to medium throttle pressure. If I only apply very light throttle pressure, the engine doesn't buck. (decelerating to slight acceleration engine speed under 1,500 RPM. At higher RPM it bucks less)

I have two choices now regarding spark plugs, try different gaps and try new spark plugs. I say try different spark plug gaps because my old plugs had a gap of .046 so I set it to the minimum .040 I found a range of 040 - .044 on one site (Rock Auto) that sold Aveo spark plugs.

Back in 1964 I worked in an auto repair shop and we had a spark plug tester where we could change some of the test inputs. The higher the air pressure we applied, the more the spark plugs failed. I don't remember if we could adjust the spark voltage or not. We also did some night time tests to see if there was any glow around the porcelain to steel shell base, which was how well the gas seal was between the ceramic and steel.

What I found was most spark plugs failed the tests if the gap was correct (.035 then) and center electrode was rounded off. Square off the center electrode and remove a little ground electrode metal by filing it a little and it passed the test with flying/winning colors.

More spark plugs failed as the air pressure was increased. Back then the debate was which brand of spark plug worked the best. Most popular brands were the same. I did find some no-name brand spark plugs had a glow between the steel and porcelain at night. Several engines at that time were completely visible so the glow test was easy to do. I will say the test device was fairly low tech.

A couple years later the shop bought one of those big fancy automotive oscilloscopes. It was magic at first, then I learned a scope measures time and voltage. I transferred some of the knowledge I gained using the scope to hand held tools that measures voltage and resistance. The most applicable meter for spark plug wire test was how much resistance a plug wire had was the ohm meter. I marvel at how simple it is to test spark plug wires when I read how many people replace spark plug wires but never test them.

Of course ohm meters do not replace digital scopes in some situations but with spark lug wires and wiggling the wire as several places,an ohm meter is a low cost way determine good from bad spark plug wires. A few times when I found a bad wire, I cut off an inch and re-attached a connector. It worked until I could buy new wires. In one shop we made wire sets from individual parts and a roll of spark plug cable that worked as well as an OE part. A special crimping tool was the key to making up a wire/cable that lasted.


I read there was a recall on 2009 Aveos because the spark plug boots were defective but nothing on 2008 Aveos. My Aveo was built in 2007 around Sept.

I bought a can of Mass air flow sensor cleaner but I haven't used it yet. I will look again for any air leaks.

I have a reference to an independent repair shop with some sort of digital scope but have not contacted him.