5.7l tbi misfire in Park

[Mr.hillbilly]

All right, so this is the third time I’m posting about this still can’t figure it out all right so about two years ago, I resurrected my truck from the dead. And I rebuilt the entire TBI throttlebody I mean everything everything in that throttlebody got rebuilt and replaced. But I put cheap Amazon injectors into it but after I rebuilt the throttlebody, it ran great but then one day I was pulling into my driveway and one of my injectors went out and so I bought oem set of injectors and when I just replaced the injectors, I replaced both of the gaskets and O-rings on the injectors and and then ever since I did that it’s had a misfire at idle in park, but only when the truck is warm when the truck is cold and in park, it runs fine but once it starts warming up, it starts doing a little popping misfire and then when I put the truck into drive and put some sort of load onto the engine, it runs fine so it only misfires in park and I have replaced a spark plugs and spark plug wires. My EGR is not stuck open. My cats are not clogged because i don’t have any cats on the vehicle and I sprayed brake cleaner all around the vacuum lines and throttlebody gaskets and I couldn’t find anywhere where there would be a vacuum leak so I’m completely lost

 

[Blue85]

https://ck5.com/forums/threads/5-7l-tbi-missing-firing.351446/
https://ck5.com/forums/threads/5-7l-tbi-misfiring-at-idle.351922/

It's possible the issue only occurs in closed loop. You could verify this by unplugging the oxygen sensor and see if the misfire goes away. Typically, that would imply a vacuum leak or exhaust leak. Even if the throttle body gaskets are perfect, you could have a crack in a vacuum line or something like that (for example, the line going to the MAP sensor). You can also develop a leak in the brake booster. You could try plugging some lines to test. Someone will probably also ask how you know the EGR isn't hung and maybe suggest trying a block-off for troubleshooting.

Do you have a scan tool? A vacuum gauge? Fuel pressure gauge?

 

[Mr.hillbilly]

https://ck5.com/forums/threads/5-7l-tbi-missing-firing.351446/
https://ck5.com/forums/threads/5-7l-tbi-misfiring-at-idle.351922/

It's possible the issue only occurs in closed loop. You could verify this by unplugging the oxygen sensor and see if the misfire goes away. Typically, that would imply a vacuum leak or exhaust leak. Even if the throttle body gaskets are perfect, you could have a crack in a vacuum line or something like that (for example, the line going to the MAP sensor). You can also develop a leak in the brake booster. You could try plugging some lines to test. Someone will probably also ask how you know the EGR isn't hung and maybe suggest trying a block-off for troubleshooting.

Do you have a scan tool? A vacuum gauge? Fuel pressure gauge?

I have a fuel pressure gauge