An idle surge, or 0300 service code, can have multiple sources behind the issue. Some examples include: different style intakes, large injectors (without boost reference fuel pressure) or vacuum leaks. Finding the vac leak, fixing it, and dialing in your fuel trims can help reduce idle surge. You can also remove your injectors, inspect the O-rings, re-grease them, and reinstall. Every intake will have a big effect on your MAF sensor chart in the PCM, we’ve even seen different intakes sway the MAF chart plus or minus 40% at times. The only cure is to diagnose and repair the vac leak, and tune the fuel trims in with tuning software such as HPTuners.
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