# What causes an engine to run lean **URL:** \ **Category:** PittSpeed Automotive\ **Created:** [April 20, 2007, 10:53pm UTC](https://forums.speedlife.net/t/what-causes-an-engine-to-run-lean/189422 "2007-04-20T22:53:35Z")\ **Posts on this page:** 1\ **Showing post:** 12
**Author:** ![neonmike22](https://avatars.discourse-cdn.com/v4/letter/n/ba8739/32.png) [@neonmike22](https://forums.speedlife.net/u/neonmike22)\ **Post date:** [April 22, 2007, 9:17am UTC](https://forums.speedlife.net/t/what-causes-an-engine-to-run-lean/189422/12 "2007-04-22T09:17:30Z")
> [@I hate cars......](https://forums.speedlife.net/t/i-hate-cars/29655/7): > > The overall problems on my car are as follows(this may help u guys a lil more) EGR sys failure(2nd time the light came on for this) My injectors may be bad…seafoam cleaned them up for a while and mileage went back up but not for long, oil in plug #4, plugs were gaped at 040 when on neons they should be 035(corrected this problem), loose bolt near the cat which rattles from time to time EGR valves in general suck. You’d either need to pull it off and clean the passages, or replace it with a new one. The oil on the plug could be the spark plug tube seal. That loose bolt isin’t causing an exhaust leak? --- _[View the full topic](https://forums.speedlife.net/t/what-causes-an-engine-to-run-lean/189422)._