So, I spent a day last weekend getting intimate with my new-to-me 09 Championship Edition with 118k miles to replace the spark plugs. What a beast of a job - clearly intended for someone with longer arms and smaller hands than me!

Based on long-ago superseded part numbers I'm pretty sure these were original. Five of them were still at the factory .040 gap, and the remaining three were between .040 and .045. I always understood clean/white was a sign of running too lean and ideal was even tan deposits, but that was in carburetor engines. So, wondering what folks here think of these - are these normal for the 5.3, or not?

I'm also chasing a slight rough idle at cold start that produces mild chassis vibration for about 30 seconds before it smooths out. This is when its 70F outside, so not sure what it will be like once the weather turns colder. So far I've cleaned the MAF and throttle body, replaced plugs, wires and new air filter. Also about 30% of the way through a tank with Techron. Cleaning the MAF and throttle body produced a slight improvement, but did not eliminate the roughness. The new plugs/wires didn't improve things. Still have my fingers crossed on the Techron. No codes. Any thoughts on other things to look at or try, or is this normal for the V8?



Left to right 8 through 1

Left to right 8 through 1

 

They actually look pretty good for being almost 20% over 100K miles. They may have looked a bit better 15K miles back. Could have been changed earlier, but no foul there. Note that pun...........

My 09 Alpha seems smooth right at startup, but it may be a matter of interpretation.

 

Thanks Doc. I've only owned the truck for 300 miles, so totally agree that the timing on the plugs could have been advanced a little ...

 

12571164 was replaced in 2008 with 12621258, replaced again with 12609877,and again with the current oem#: 12680072.

 

.040? You either need glasses or a new gauge?

 

Plugs look good, strap looks pretty much on or next to the welds which is typical for stock tune gasoline cars.

Do you know if this one was tuned previously or not? Has it always been doing this since you've owned the vehicle? A great way to help diagnose the post-start up roughness at idle would be to hook up a laptop with HPTuners or similar software to monitor and datalog all the PIDS so you can see what it's doing.

If it was tuned before, then I definitely could see it being the tune. Cold start tuning can be tricky to perfect, usually stock tunes on stock components are spot on. Even if it's not tuned, hooking up a laptop to see what it's doing would be extremely helpful if you or a buddy can do it.

 

 

Thanks - great feedback. I'm guessing no custom tune since everything on the truck is pretty much stock and it still had original plugs and wires after 118k. Someone who tunes their engine would have swapped those parts out long ago! Unfortunately, I have no buddies with HPTuners. I'll see if it clears up any after I finishing running this tank of gas with Techron, and if that doesn't help I'll look into the HPTuners option.

 

There really is no reason to change plugs or wires until 100K, tune or no tune. Recent high efficiency electronic distributorless ignitions are a HUGE improvement over the ignitions of yesteryear. With these trucks being older, there may have been a tune by some prior owner and the people after had no idea, but it would only be a guess. Anything is possible.

You could look to see if you have a local tuner nearby and what they would charge to check what is on your PCM to confirm stock or modified.

 

I would say they look good with a few slightly on the lean side. I would keep doing the techron or a real injector cleaning service. Also the easy things, fuel filter if it has one, MAF and throttle body cleaning.