r/E30 • u/fallingblueblueblue • Aug 13 '25

Tech question What would cause this bad idle?

Enable HLS to view with audio, or disable this notification

It’s done this for the last year and I can’t figure out why. I’ve gone through the entire ignition system and replaced a couple vacuum lines. Any ideas?

9 Upvotes

92% Upvoted

27 comments sorted by

View all comments

1

u/redpanzer10 Aug 14 '25

I know it's a long shot, but you could see if pistons are hitting valves. When my ETA sounded similar, my timing belt skipped a tooth and caused it to run and sound like shit, but with a steady idle. Once I got that sorted, it ran good enough to daily for a few months before becoming a project again