Power Loss Under Load with Injector Contribution Imbalance
Power loss with contribution imbalance is resolved by electrical proof and return-flow testing on the low cylinders before any injector replacement.
Fault Overview
Symptom page for power loss under load when contribution or balance testing reveals one or more low-contributing cylinders, with or without circuit codes.
Engine & Platform Coverage
Symptoms
- •Power loss injector imbalance
- •Low contribution under load
- •Weak cylinder power loss
- •Injector balance power loss
- •Derate feel from injector
Possible Causes
- 1.Electrical circuit fault on the low cylinder
- 2.Mechanically worn injector (high return flow)
- 3.Low compression on the affected cylinder
- 4.Fuel restriction affecting one bank
- 5.Incorrect calibration codes
Wiring & Circuit Notes
Electrical proof on every low-contribution cylinder before mechanical injector diagnosis. Resistance and current checks on low cylinders.
DVOM Specs & Sensor Tests
Contribution percentages or RPM drop under load or during test mode. Resistance and current on low cylinders. Return-flow volumes. Relative compression if available.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
6 steps locked behind Technician Mode- 1Step 1 — Run Contribution/Balance Test Under Load Conditions: Run contribution/balance test under the conditions that produce the complaint if possible. Record results for all cylinders.
- 2Step 2 — Identify Low Contributors: Identify low contributors. Note which cylinders fall below OEM limits.
- 3Step 3 — Full Electrical Checks on Low Cylinders: Perform full electrical checks on low-contribution cylinders before mechanical injector diagnosis. Electrical proof on every low-contribution cylinder is mandatory.
- 4Step 4 — Return-Flow Test if Electrical Good: If electrical is good, run return-flow test. Measure volumes from all cylinders and compare to OEM limits.
- 5Step 5 — Check Relative Compression if Return Flow Normal: If return flow is normal, check relative compression. Low compression with normal contribution points to mechanical issues.
- 6Step 6 — Verify Calibration Codes: Verify calibration codes on any recently replaced injectors.
- 7Step 7 — Repair Only Proven Failed Items and Retest: Repair only the proven failed items and retest contribution. Confirm power is restored before releasing the vehicle.
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
Typical Repair Costs
Electrical repair $100–300; individual high-return injector replacement $300–700; mechanical engine repair if compression related — variable. Avoid full injector sets.
Start Diagnosing This Fault Now
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Summary
Use the AI Diesel Tech diagnostic engine to run this code through a structured, evidence-gated sequence and get a confirmed root cause before any parts are replaced.