Symptom Medium Severity Safe to Drive: Caution During Acceleration

Why Your Car Feels Rough During City Driving (Low-Speed Rough Running)

Rough performance during city driving often stems from unstable engine combustion, fuel delivery, or transmission control issues at low speeds. Early detection prevents further damage.

Potential Causes

Dirty fuel injectors Medium Probability

Clogged injectors lead to uneven fuel delivery causing misfire and rough operation at low speeds.

Spark plugs/ignition coil wear High Probability

Worn plugs or weak coils cause poor combustion and misfires that are noticeable during city driving.

Throttle body or MAF sensor contamination High Probability

Contamination disturbs air/fuel balance and control, leading to unstable engine response in stop-and-go traffic.

Transmission control or ATF issues Medium Probability

AT/CVT fluid degradation or control issues can result in jerky power delivery during low-speed acceleration.

Engine or transmission mount wear Low Probability

Degraded mounts transmit vibration to cabin, felt as roughness even if engine running is marginally unstable.

Diagnostic Steps

  1. Check for Misfire Codes

    Use OBD2 scanner to check for P0300, P0171, and other misfire-related codes.

  2. Inspect Ignition Components

    Remove and inspect spark plugs & coils for wear or fouling.

  3. Clean Air Intake Components

    Clean throttle body and MAF sensor to ensure proper air flow measurement.

  4. Check Transmission Fluid

    Inspect ATF/CVTF level and condition; replace if dark or burnt smell present.

DIY Fixes

Replace Spark Plugs Beginner
Estimated Cost: $40 - $120

Clean Throttle Body Intermediate
Estimated Cost: $0 - $30

OBD-II Live Data Analysis

Use a scan tool to monitor these parameters. Comparing live values against the normal range can help identify the root cause.

PID

Long Term Fuel Trim (LTFT)

Normal Range +/- 10%
Abnormal Condition > +15% (Lean)
Technical Insight: Indicates unmetered air or poor fuel delivery causing rough running even without codes.
PID

Misfire Counter

Normal Range 0
Abnormal Condition > 0
Technical Insight: Shows misfire detected on one or more cylinders during low-speed conditions.

Frequently Asked Questions

Why does my car feel rough when driving in the city?

A rough feeling during city driving can be caused by several factors, including dirty fuel injectors, worn spark plugs or ignition coils, and contamination in the throttle body or MAF sensor. These issues can disrupt engine performance, especially in stop-and-go traffic.

What are the common causes of a rough engine while driving?

Common causes of a rough engine include dirty fuel injectors, worn spark plugs or ignition coils, and contamination in the throttle body or MAF sensor. These components play a crucial role in maintaining smooth engine operation.

How can I diagnose why my car feels rough during city driving?

To diagnose the issue, use an OBD2 scanner to check for misfire-related codes like P0300 or P0171. Additionally, inspect the spark plugs and ignition coils for wear, and clean the throttle body and MAF sensor to ensure proper airflow.

Can I fix a rough engine feeling myself?

Yes, you can perform some DIY fixes such as replacing worn spark plugs and cleaning the throttle body. These steps can help restore smooth engine performance and resolve rough driving symptoms.

What should I do if my car continues to feel rough after cleaning the throttle body?

If your car still feels rough after cleaning the throttle body, consider checking the fuel injectors and inspecting the ignition system, including spark plugs and coils. If issues persist, it may be best to consult a professional mechanic for further diagnosis.

Commonly Related Terms

Car runs rough at low speed Engine vibrates in stop-and-go traffic Low speed rough drive feel Jerky acceleration at city speeds

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