Oil on spark plugs - misfiring p0300

[FAUST]

On it! I’ll do that today and see where I’m at!

Also - I have found what y’all are saying about the seals. Thank you all for confirming!

I hope it’s an easy fix - PCV - I’ll let y’all know what I find. If not the easy, I’ll go down the list.

Thanks again!

 

[FAUST]

On it! I’ll do that today and see where I’m at!

Also - I have found what y’all are saying about the seals. Thank you all for confirming!

I hope it’s an easy fix - PCV - I’ll let y’all know what I find. If not the easy, I’ll go down the list.

Thanks again!

PCV checked - vacuum there. Now I need to work through the list of fixes - I’ll start by checking the valve cover and make sure it’s the latest.

Then I’ll work on injectors.

Symptoms I’ve been observing - the truck doesn’t have any odd sounds or anything while running - the main issue I have is the shuttering feeling at low RPM when accelerating and when decelerating - it’s very obvious when coming to a stop at low RPM and when climbing a hill at low RPM.

Could it be something with the 4WD or something with the wheel hub?

I’m at a loss and not in a position to pay a shop for diagnostic again (3x - replaced o2 sensor and found nothing else).

Again - any ideas or help is appreciated!

 

[j91z28d1]

it's been my experience, not with these trucks but just engines in general, if they only miss under load, especially low rpm load it's normally weak spark for some reason. fouled or glazed plugs, bad cold or wire, low compression and could be fuel injector, but I've never actually had just one bad fuel injector go bad before, but I'm sure it does happen and I always check.

low rpm high load is when it's felt the most because of the longer time between firing. higher rpm miss feels smoother. you'll hear a lot of times people say it clears out when it's run higher rpm. it's just how it is.. miss is more noticeable at low rpm and more load. like say taking off in 3rd gear instead of 1st gear.

 

[Fless]

I don't see it mentioned but may have missed it. How clean is the throttle body and/or how long ago was it cleaned?

 

[Rocket Man]

Are you sure it’s not torque converter shudder? What trans do you have? I know the 6l80’s have that issue.

 

[strutaeng]

You need to invest in a diagnostic tool that reads live data (and gives specific misfire count per cylinder) and spend some time on YT learning how to diagnose a misfire to find this.

An injector balance test is also going to be helpful.

 

[FAUST]

I don't see it mentioned but may have missed it. How clean is the throttle body and/or how long ago was it cleaned?

Throttle body was cleaned less than a year ago - cleaned meaning I removed the throttle body and cleaned it front to back.

 

[FAUST]

Are you sure it’s not torque converter shudder? What trans do you have? I know the 6l80’s have that issue.

I am not sure what trans is in this truck - I will assume it’s stock - 2007 Tahoe LTZ. 5.3L.

I’ll look at how to diagnose that.

 

[FAUST]

You need to invest in a diagnostic tool that reads live data (and gives specific misfire count per cylinder) and spend some time on YT learning how to diagnose a misfire to find this.

An injector balance test is also going to be helpful.

I’ve seen mention of a specific tool for these rigs - do you have a suggestion?

I agree with you 100% - before I became engulfed in this process I spent $100 on blue driver scan tool - it has the ability to see misfires on each cylinder but it’s not live.

I’m trying to do what I can without spending a ton of money on “fixes” that aren’t fixes.

I’m sure y’all have been here before - 3 kids in private school, Mtg, extra curricular, etc. just not a lot of expendable cash.

This forum has been helpful, I’ve learned a ton about the engine and engines in general - for that I am grateful.

Thanks for continued support and brainstorming to help a new wrench turner along.

 

[FAUST]

Throttle body was cleaned less than a year ago - cleaned meaning I removed the throttle body and cleaned it front to back.

Some before and after pics.