So I've been driving my S4 n/a for a couple days now and have discovered a few things that possibly need to be fixed.

1. Loud pops when I'm shifting (happens quite often), I'm thinking backfires, but I haven't really had the chance to see if flames come out. I know this is a product of running too rich, and possibly other things. What harm/damage can this cause to the car if left unfixed?

2. Shift **** vibrates quite loudly in 3rd gear at higher rpm's.

3. The car is quite jerky when I let off the gas and let it decelerate normally. This doesn't happen at higher speeds.

If any of you rotary pros have any ideas what might cause these things, or if these may be symptoms of more serious problems, any feedback is appreciated! Thanks!

 

1. Check your TPS adjust it, check timing, adjust idle.
2. Not Sure
3. In what gear are you experiencing this? My slightly does it with first gear when I first got the car, doesn't do it now though. Could possibly be due to a bad or misadjusted TPS, again first check this. Possibly worn out motor/tranny mounts too.

 

Driveline slack is common in these cars...it can be made somewhat better by replacing your engine mounts and transmission mounts to dampen the shock when you let off the gas. Adjusting your TPS may or may not help this.

The shift **** lever rattling is a metal-on-metal reaction. Replace your shifter bushing appropriately and get a first gen Miata shift ****. Problem solved.