My Codes; P0300, B0090, U1096

Grubbworm · October 8, 2023

My wife & I recently went on a Camping, Biking, Fishing, Kayaking, Vacation Trip. I towed a 16 ft. camper and a loaded truck. On the way up there the truck ran like it had very a slight misfire.. On the way back the misfire was so bad that the check engine light came on. I pulled the plugs and checked the gaps, all were slightly under the .040 OEM recommendation. I then inspected, cleaned, re-gaped, and anti-seized before reinstalling them. I then removed the O2 Sensor and had a look at it, before cleaning anti-seizing, and reinstalling. I also checked the Spark Plug Wires. 5 of them Ohmed out at about 950-1200 Ohms per foot. The other 3 were defective. Here are the pictures of the spark plugs before I cleaned and re-gapped them.

Grubbworm · October 8, 2023

I am also attaching the pictures of the O2 Sensor from the previous post.

Grubbworm · October 9, 2023

I am considering changing my spark plug wires to an 8.5mm, 500 ohm per foot or less wire. I feel that that should keep the spark plugs happy with all of the spark that they can handle. The Spark Plugs are NGK Iridium TR5 IX.

diyer2 · October 9, 2023

I would use OEM wires and plugs.

YMMV

newdude · October 9, 2023

The only code you've got that's related to drivability is the P0300.

How many miles on the truck? Have the plugs ever been replaced before? What brand plugs are they? Wires. OEM or have they been changed?

Naughty Donkey Performance · October 9, 2023

Odd that so many wires tested poorly all at once........good place to start though is where you are going already with it.

Keep us posted as to how it turns out please.

Grubbworm · October 9, 2023

These are the wires that I am considering purchasing.

More Information for STANDARD MOTOR PRODUCTS 10074 (rockauto.com)

Grubbworm · October 9, 2023

11 hours ago, newdude said:

The only code you've got that's related to drivability is the P0300.

How many miles on the truck? Have the plugs ever been replaced before? What brand plugs are they? Wires. OEM or have they been changed?

175,000 miles on this truck. Yes, got the truck with 160,000 miles on it. Replaced the plugs and wires several years ago. We do not drive this truck everyday. The Spark Plugs are NGK Iridium TR5 IX. The wires are Ultima Select 7mm.

diyer2 · October 9, 2023

Just curious if I understand this.

You replaced the plugs and wires 15k miles ago with aftermarket parts and you're getting codes for misfires. Why go aftermarket parts again?

If you search this site you will find OEM wires and plugs work the best I beleive.

Someone prove me wrong.

newdude · October 9, 2023

42 minutes ago, Grubbworm said:

175,000 miles on this truck. Yes, got the truck with 160,000 miles on it. Replaced the plugs and wires several years ago. We do not drive this truck everyday. The Spark Plugs are NGK Iridium TR5 IX. The wires are Ultima Select 7mm.

I'd get some OEM plugs and wires and then re-test, see if it continues to misfire. GM trucks/SUVs are very sensitive to aftermarket ignition components and engine sensors, especially O2 sensors. Never run an aftermarket O2 sensor.

Grubbworm · October 10, 2023

All of the OEM wires, and also the lesser quality manufactured ones that I have used in the past for various vehicle applications have had issues with the sparkplug metal end in the wire pulling off of the wire itself and staying on the spark plug. This does not happen all of the time, but more times with the lesser wires. I have used higher quality spark plug wires in the past with better results.

As far as the Spark Plugs themselves, the plugs that are in there currently are very good quality and still in good shape and have been working fine. I am not changing them currently.

These are the wires that I am going to use based on the double crimp that they use on the ends, among other things. MSD SUPER CONDUCTOR SPARK PLUG WIRE SET -1999-05 GM TRUCK

Red Jacket - Gen III LS 4.8/5.3/6.0 Part # 32829

I should also say that I use Dielectric Grease in both ends of the wires and have for years with great results. I also use anti-seize on the spark plug threads.

Edited October 10, 2023 by Grubbworm

diyer2 · October 10, 2023

Sounds like you are doing it the right way. I would recommend a spark plug boot removal tool.

Grubbworm · October 10, 2023

1 hour ago, diyer2 said:

Sounds like you are doing it the right way. I would recommend a spark plug boot removal tool.

I already have one. I have had it for years. I believe it is a Lisle.

Edited October 10, 2023 by Grubbworm

diyer2 · October 11, 2023

I have never had your problem of pulling plug wires apart. I always twist the spark plug boot to free it before pulling on it.

Thought maybe this tool would help.

Grubbworm · October 11, 2023

7 hours ago, diyer2 said:

I have never had your problem of pulling plug wires apart. I always twist the spark plug boot to free it before pulling on it.

Thought maybe this tool would help.

I have only occasionally dealt with this issue in the past. Except for this truck and the LS engines with the metal heat shields, they seem to be more prone to this problem. And this tool does help somewhat.