Low rpm intermittent shudder - ZR-1 Net Registry Forums

BlueDevlC7z · 10-17-2022

Hello my Z brothers. Looking for opinions. My 93 Ruby with 22k started to intermittently shudder a few months ago. It would be most noticeable at loads under 2200 rpm. It?s not noticeable after that all the way to 7k. Last summer I replaced all 8 original plugs with AC Delco 41-913. Ran fine till this spring. I started digging after it and wound up replacing the #8 plug. Still had the shudder. I drove the car the last 2 days and it ran smooth as glass. I?m thinking it?s a sign of one of the coil packs wearing out. I don?t think it?s a fuel or injector issue as it pulls strong to redline and it probably wouldn?t if it were a bad injector or bad fuel pump(s). No mods to engine and has original wires and coils. Any help gladly appreciated.

10-17-2022	#1
BlueDevlC7z Join Date: Aug 2019 Location: Montgomery, NY Posts: 26	Low rpm intermittent shudder Hello my Z brothers. Looking for opinions. My 93 Ruby with 22k started to intermittently shudder a few months ago. It would be most noticeable at loads under 2200 rpm. It?s not noticeable after that all the way to 7k. Last summer I replaced all 8 original plugs with AC Delco 41-913. Ran fine till this spring. I started digging after it and wound up replacing the #8 plug. Still had the shudder. I drove the car the last 2 days and it ran smooth as glass. I?m thinking it?s a sign of one of the coil packs wearing out. I don?t think it?s a fuel or injector issue as it pulls strong to redline and it probably wouldn?t if it were a bad injector or bad fuel pump(s). No mods to engine and has original wires and coils. Any help gladly appreciated.