00 Denali - Random Misfires under load

[gpracer1]

I will post a pic of the plugs if anyone would like, they all looked exactly the same. They were not wet or otherwise bad besides the obvious signs of misfiring and some detonation.

Good focused close up pics...

 

[SunlitComet]

yes on plugs and location of each. Also what scanner model do you have?

 

[TurboGSR96]

I have a cellphone, this about the best its going to get... lol Only took 2 pics then picked them up. Pics came out pretty damn good though, not much to see they are definitely toast.


If you zoom in they are really clear...


Is there a possibility the strainer or "pre filter" on my fuel pump is clogged? I would think you would still get the same fuel pressure just less flow. I remember last summer I dumped several different expensive carbon cleaners in the fuel tank over a couple tanks thinking the injectors were clogged and the problem went away for a few weeks almost entirely.

---------- Post added at 07:19 PM ---------- Previous post was at 07:06 PM ----------

Kal equip #9615 is the model of the scanner, its ancient and cheap...

 

[TurboGSR96]

The truck was misfiring really bad then I shut it off to put the plugs in, I gave it a little too much for too long and it was shaking real bad when I shut it off... they look a little lean to me.

 

[gpracer1]

I just went through this whole thread from the start.

Did you ever clean the INSIDE of the MAF, both sides of the honeycomb with MAF cleaner.......I mean spraying half of the can on both inside front and back? 10 min job.

While the plugs were out, you should have done a compression check , just incase you have a problem like sunlit.

If your MAF is really dirty or bad, it will under-report the amount of air going into the engine and give you way less fuel than it needs.

 

[SunlitComet]

How old are these plugs as where is all the rust coming from?

---------- Post added at 08:12 PM ---------- Previous post was at 08:11 PM ----------

Would like some more pics with the plugs rotated 180 if you can please?

---------- Post added at 08:13 PM ---------- Previous post was at 08:12 PM ----------

just put #1 on a piece of paper nearby so you don't have to take time editing the photo with labels.

 

[TurboGSR96]

I just went through this whole thread from the start.

Did you ever clean the INSIDE of the MAF, both sides of the honeycomb with MAF cleaner.......I mean spraying half of the can on both inside front and back? 10 min job.

While the plugs were out, you should have done a compression check , just incase you have a problem like sunlit.

If your MAF is really dirty or bad, it will under-report the amount of air going into the engine and give you way less fuel than it needs.

Yes I cleaned the MAF spotless a few weeks ago, no change at all.

How old are these plugs as where is all the rust coming from?


---------- Post added at 08:12 PM ---------- Previous post was at 08:11 PM ----------

Would like some more pics with the plugs rotated 180 if you can please?


---------- Post added at 08:13 PM ---------- Previous post was at 08:12 PM ----------

just put #1 on a piece of paper nearby so you don't have to take time editing the photo with labels.

Plugs maybe a little over a year old... I expect them to rust in my area with all the running around in snow and on the beach I do. I will take some more pics tomorrow when I get better light, they dont tell you much but the obvious... heavy misfiring and detonation. The timing straps look a little white for my liking I am thinking its running lean...

 

[SunlitComet]

If fuel system had any kind of flow issue a pressure gauge would drop or flutter real bad as soon as you hit the throttle.

---------- Post added at 09:18 PM ---------- Previous post was at 09:18 PM ----------

What plugs and gap are you running? They look to be the wrong kind.

 

[TurboGSR96]

They werent AC Delco, I think they were autolite or something like that. Definitely the correct size and .060 gap though I compared them to the new plugs.

 

[SunlitComet]

They did not look like full platinum either. They seem to be missing the platinum on the ground electrode. It probably safe to say they are damaged enough to warrant new ones.