# P0300 with lean running **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** mazda, miata\ **Created:** [October 23, 2009, 5:34pm UTC](https://community.cartalk.com/t/p0300-with-lean-running/38511 "2009-10-23T17:34:27Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![NatReader](https://avatars.discourse-cdn.com/v4/letter/n/5f8ce5/32.png) [@NatReader](https://community.cartalk.com/u/NatReader)\ **Post date:** [October 23, 2009, 5:34pm UTC](https://community.cartalk.com/t/p0300-with-lean-running/38511/1 "2009-10-23T17:34:27Z")
Date History: Problem started 9/23/2009 with a P0302 and has been P0300 since Happens every 2-4 days between 50 and 200 miles driven since something was fixed and light reset. When Problem occurs: Usually morning when engine is still warming up in first 5 miles of driving. Speed usually constant, RPM around 3000 Major System Test History:[/B][/U] 1. Compression - passed 2. Vacuum - passed 3. Smoke - passed 4. EGR - passed Parts replace: Sparks plugs coil pack Injector o rings Parts repaired: Timing belt that slipped a tooth Performance: Not bad now. Accelerated smoothly through all gears this morning Idle at 800. That bucking went away after timing belt fixed. CEL threw and I did not even know it till I looked down. Can hear mild popping sound at air intake when throttling from inside engine mildly. ---
**Author:** ![Bladecutter](https://avatars.discourse-cdn.com/v4/letter/b/aeb1de/32.png) [@Bladecutter](https://community.cartalk.com/u/Bladecutter)\ **Post date:** [October 23, 2009, 5:41pm UTC](https://community.cartalk.com/t/p0300-with-lean-running/38511/2 "2009-10-23T17:41:10Z")
How many miles are on the car? Have you ever replaced the O2 sensors? BC. ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [October 23, 2009, 5:52pm UTC](https://community.cartalk.com/t/p0300-with-lean-running/38511/3 "2009-10-23T17:52:27Z")
Where does the reference to “lean running” come in? Was there a code in there for that? If so, what was it? If you’re getting the CEL without any noticeable problem, then it is unlikely to be from a misfire code. Possible - but normally a misfire bad enough to set the code is felt. I’m guessing that the “bucking” and the misfire code came together, but it is hard to interpret what you’re reporting in terms of the past & present. ---
**Author:** ![NatReader](https://avatars.discourse-cdn.com/v4/letter/n/5f8ce5/32.png) [@NatReader](https://community.cartalk.com/u/NatReader)\ **Post date:** [October 23, 2009, 5:55pm UTC](https://community.cartalk.com/t/p0300-with-lean-running/38511/4 "2009-10-23T17:55:55Z")
It throws a P0300 every other day. Performance problems…rough on idle again, popping sound from air intake, no acceleration…foot to floor on highway only gets slow smooth. The lean has to do with the cars performance, my mechanic agrees that the car is running lean. ---
**Author:** ![NatReader](https://avatars.discourse-cdn.com/v4/letter/n/5f8ce5/32.png) [@NatReader](https://community.cartalk.com/u/NatReader)\ **Post date:** [October 23, 2009, 5:57pm UTC](https://community.cartalk.com/t/p0300-with-lean-running/38511/5 "2009-10-23T17:57:13Z")
68,000 Yes on 02 sensor, yes on spark, yes on wires, yes on coil, yes on injector, yes on o rings at injectors… Have done smoke, compression, vacuum and EGR tests. ---
**Author:** ![NatReader](https://avatars.discourse-cdn.com/v4/letter/n/5f8ce5/32.png) [@NatReader](https://community.cartalk.com/u/NatReader)\ **Post date:** [October 23, 2009, 5:58pm UTC](https://community.cartalk.com/t/p0300-with-lean-running/38511/6 "2009-10-23T17:58:43Z")
oh and all those parts replacements are in the last 14 days. And timing belt is good, just fixed it 4 days ago