Troubleshooting Misfires and Low Mileage in Modified 2ZZGE EE90 Corolla

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Troubleshooting Misfires and Low Mileage in Modified 2ZZGE EE90 Corolla

Since 2018, Ive had a 2ZZGE engine in my EE90 Corolla. A standard tune was completed two years ago, utilizing a stock ECU with an FPR, custom headers, cold air intake, and a 2.7 downpipe connected to a Power Pro exhaust.

The trouble began when I swapped the custom 2.7 downpipe and exhaust for a 2.2 setup. The issue presents as misfires, rough idling, and occasional s in RPM, emitting black smoke with a foul smell from the exhaust. Mileage has also decreased by half.

This predicament started about 5 months ago with minor, barely noticeable misfires at 2500 RPM on the motorway. It escalated from there, with misfires occurring more frequently and the car becoming increasingly unstable. Ive replaced the AFM sensor, tried different types including changing from type C to a standard version, checked and cleaned various components, replaced the fuel pump, and addressed exhaust manifold leaks. Despite intermittent improvements, the misfires persist after a few days.

Im seeking advice on achieving smooth operation no misfires and improved mileage no black smoke without resorting to remapping by a tuner.

Thank you for your insights

Zohaib Hussain asked on 09 Aug 2023 18:10:39 pm

1 Answer

14 views |

Ayaan Khan - on 10 Aug 2023 16:30:46 pm

Initially, consider the duration of breath-holding without mouth opening o r nostril obstruction, followed by addressing potential problems in an 1800 cc engine:

Calculate breath-holding capacity with closed mouth and unobstructed nostrils.
For an 1800 cc engine, focus on resolving issues likely caused by a malfunctioning Mass Air Flow MAF sensor due to improper intake conditions:

Revert to the original stock intake configuration.
Evaluate the PCV Positive Crankcase Ventilation valve.
Conduct a comprehensive compression test, both dry and wet, comparing results against the standard 11.5:1 ratio.
Recognize that various complications could contribute to misfires, including:

Identifying and addressing potential vacuum leaks.
Inspecting and potentially replacing malfunctioning injectors.
Assessing the condition of ignition coils and addressing any problems detected.
These steps will facilitate effective troubleshooting and remediation for your engine-related concerns.