5.7l tbi misfiring at idle

[Mr.hillbilly]

so for a couple months now I’ve been experiencing this really annoying issue and this is kind of a quick explanation. What happened so basically I put cheap Amazon injectors in it to get me by for a couple months because the truck had sat for seven years I didn’t know if their original injectors were good so I just bought cheap ones and I was driving home one day and I was about to pull into my driveway when it just started running on four cylinders and luckily I was able to lip it up my driveway and then when I got in my driveway, I looked underneath my hood. I started to back up, and I saw that one of my injectors wasn’t spraying so just to see I put my old injectors back in and they were spraying fine. Everything looked great but ever since I did that whenever I started it and it’s idling it starts misfiring and I don’t know what could be the cause. But when I actually start driving a truck that runs great it doesn’t misfire I don’t feel any power loss. It’s only when it sits and starts idling I don’t know what it could be at this point. I’ve replaced the entire ignition system and it’s still doing it and i’ve also checked for vacuum leaks

 

[Fastereddie]

My ‘90 burb has does the same, but it’s intermittent. I haven’t found the cause yet.

 

[dyeager535]

It's been awhile since I've messed with TBI, but aren't there a few seals used with the injectors when swapped out?

If so, can you have someone turn the key to "run" while watching the throttle bores and see if you've got any leaks as the pump pressurizes the system?

You may also need to check for vacuum leaks if there are any surfaces that required sealing to swap injectors.

Your injector wires are in good shape? They are often in poor shape due to the way they are held in, if you don't pay attention when messing with the air cleaner/wiring they can get pinched/frayed IIRC.

 

[Mr.hillbilly]

Yeah, there’s a couple seals that you need to replace when you take out the injectors I have pretty much replaced every gasket every seal on my throttlebody at this point, I haven’t checked for vacuum, which is the next thing I’m gonna do and I haven’t really checked for leaks, which will be my next thing as well thank you for the help

 

[Fastereddie]

Yeah, there’s a couple seals that you need to replace when you take out the injectors I have pretty much replaced every gasket every seal on my throttlebody at this point, I haven’t checked for vacuum, which is the next thing I’m gonna do and I haven’t really checked for leaks, which will be my next thing as well thank you for the help

Maybe the egr is stuck partially open.

 

[Bent77]

Maybe the egr is stuck partially open.

This
And pull the plugs and look

Could have a bad plug, could have a plugged filter after sitting

 

[gmbellew]

put a timing light on each wire and make sure they are all firing.

check for a plugged up ir restricted exhaust (cat).

vacuum gauge at idle might have some clues