00 Denali - Random Misfires under load

[gpracer1]

On key on I get a 60 spike that sits at 55psi no drop
At idle I get 50psi and jumps to 60psi when floored.

Well I guess its not the pump

---------- Post added at 01:05 PM ---------- Previous post was at 12:59 PM ----------

Anyone ever have issues with a clogged cat converter?

You can drill a small hole in the exhaust and put a low pressure gauge between motor and cat if you dont want to take it all apart.
When done, tack weld the hole shut, or they actually make plugs but I prefer weld.

 

[SunlitComet]

good pump. A clogged cat could cause a lag in acceleration not really misfires. the more you push it the more the power drop off occurs.

 

[TurboGSR96]

hmmm, I am not much on blindly ordering parts but I am thinking a new Distributor and another new set of plugs and wires might be a good idea.... idk at this point.

Looked at rockauto Delphi is $262 and ACDelco is $336... grrr I hate this truck lol

 

[SunlitComet]

so a local parts store can not help with a scan?

 

[TurboGSR96]

Autozone around the corner does them. I have to constantly reset the code's to get the truck back into O/D right after it misfires so there is no code to check... And unless I literally stay into it until I think its going to blow I will not get a code, last time I saw it blink I was going up a bridge a week ago and I was losing mph fast lol.

 

[SunlitComet]

Could they do a misfire history for you?

 

[TurboGSR96]

If the history is still there after i delete the code then i am sure they can.

 

[SunlitComet]

should be I don't think the misfire history goes away unless you completely disconnect the pcm form the truck. Like a standby power thingy.

 

[TurboGSR96]

Cool ill try Autozone and if theirs cant do it my friend has a good one

 

[TurboGSR96]

Autozones was a *************, went to my friends house he has a big Matco unit it is like a 3lb mini computer... only got to use it for 10min or so before the battery died, did not see a section for any kind of misfire history, all I saw was freeze data related to the misfire.

I did get a new code from it though, P0300B