Spark Plugs - 2008 Chevy Tahoe 5.3L Flex Fuel

[Plato442]

Had a separated cat in my recently purchased 2011 Sierra Denali with 239,000 miles and it had some real valve train noise. Replaced the spark plugs with ac Delco 41162 plug that is the superseded plug, and some JBA zero ohm plug wires. Ordered 2 flowmaster 2220125 cats and welded them in and removed the 3rd downstream cat (damaged it, whoops) and it runs quieter and smooth…wouldn’t know it had 245k on it!

 

[CaptainAmerica1]

When I ordered from Amazon I was sent Chinese knockoffs. Rockauto was legitimate ACDelco…

 

[Charlie207]

Don't use the 41-110s as they have been counterfeited by the Chicoms and are destroying engines, especially from Amazon and many places on Ebay. If you do want that part number, buy only from Summit Racing, Rock Auto, or a GM Dealership.

748UU/19351570 are the OE wires, not ACDelco Professional.


As for the miss and gas mileage, what do your LTFTs look like? How about the O2 sensors? I'm thinking cats.

When I had similar wonky values (thread link here) you recommended I check the tightness of the intake manifold bolts, and after buying a new in./lb. torque wrench I confirmed that they were all loose. This would probably be part of the reason I was getting crappy MPGs.

After cleaning the MAF sensor, installing new AC Delco 41-162 plugs, and tightening the manifold bolts I had less sucking noise under the hood and picked up an honest 2 MPG on the interstate. My old plugs were waaay over gap spec.

 

[avalonandl]

Those plugs are shot.....the electrodes are basically gone...

 

[okfoz]

If you are getting a misfire, when you remove your spark plugs, make sure none of them are really oily. If you have one that has a lot of oil on it, your DOD/AFM might be on its way out. I had that happen to me, I had a misfire, changed spark plugs, but number 1 had a lot of oil. It got to the point, every 6 months I was changing #1 spark plug. Then one day it started misfiring really bad, changed spark plugs, no change, checked compression and #1 was low, but not super low. Ended up one of the DOD lifters collapsed on #1 Cylinder. I was quoted $2500-$3500 to have a "pro" fix it. I did it for under $500. I remember the release the lifter tool was $50, the reprogram of the ECM was $100 with shipping, the gaskets were around $100 I forget.

 

[Dustin Jackson]

If you are getting a misfire, when you remove your spark plugs, make sure none of them are really oily. If you have one that has a lot of oil on it, your DOD/AFM might be on its way out. I had that happen to me, I had a misfire, changed spark plugs, but number 1 had a lot of oil. It got to the point, every 6 months I was changing #1 spark plug. Then one day it started misfiring really bad, changed spark plugs, no change, checked compression and #1 was low, but not super low. Ended up one of the DOD lifters collapsed on #1 Cylinder. I was quoted $2500-$3500 to have a "pro" fix it. I did it for under $500. I remember the release the lifter tool was $50, the reprogram of the ECM was $100 with shipping, the gaskets were around $100 I forget.

@okfoz did it eat up the cam?

 

[THarber]

41-110 is an iridium plug
41-162 is a platinum plug

Tim

 

[gooffeyguy]

41-110 is an iridium plug
41-162 is a platinum plug

Tim

Those are both iridium plugs.

I think you're thinking about 41-962 which are double platinum plugs

 

[NO4NSHIT]

The downstream O2 sensor(s) would move a lot like the upstream ones when they are supposed to show little movement which is the sign of a healthy cat.

So if the downstream O2 sensors move a lot it means the cat is bad? And move a lot how please explain some of us are not so intelligent in knowing everything I might be the only one and idc oh well

 

[swathdiver]

So if the downstream O2 sensors move a lot it means the cat is bad? And move a lot how please explain some of us are not so intelligent in knowing everything I might be the only one and idc oh well

Yes, if it moves a lot it's time to replace the cat. You can see this either on a graph or by watching the O2 sensor voltage.