Which plugs are you using? Try closing up the gap on the plugs. Be aware you have to be very careful about closing the gap.

 

Delco plugs from dealer. The codes came on, then I changed plugs and coils but nothing changed in codes.

 

So to unclog, could I just run some fuel system cleaner? Or would I need to replace the fuel injector?

 

You would have to clean out the fuel rail

 

Yeah, Oldblue is right, and the fuel rail, and injectors, are a pain to get to. The suggestion from DrLoch is a good one too and cheap and easy. At high boost, the spark can blow out, a smaller gap can help.

 

Leaking Injector seals have been know to cause misses also. If you remove the injectors you need to replace the seals as well, 12653395. Then you need the Kent Moore EN-48266-2 Pusher/Sizer seal installer tools to get the injector seals back on. Since these cars are getting older I may see if I can make those tools, have a CNC shop in the building.

 

Thank you everyone!! So if I got this right, the potential cheap easy fix may be closing the gap. But otherwise, I need to pull the fuel rail, check the seals which would need to be replaced anyway, clean the rail, and potentially replace a $230 fuel injector. Would a fouled injector trip its own special code?

 

No, only the by-product of an injector problem will generate a code - ie: misfires/running rich, and in extreme conditions might throw a running lean condition.

ps: I just came across this article - it's good reading on fuel injector problems - http://www.superchevy.com/how-to/add...fuel-injector/

 

$230 for 1 injector ?

 

Naw not that much

https://www.ebay.com/itm/NEW-OEM-Bos...-/161898006254

Here’s an upgraded fuel rail and injectors

https://www.ebay.com/itm/New-Upgrade...8905197?_ul=CA