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6E–352 4JH1 ENGINE DRIVEABILITY AND EMISSIONS 10 Remove the MAF & IAT sensor assembly and check • Objects blocking at the MAF sensor element. — Verify repair Go to Step 11 11 Check the MAF sensor harness for the following • Check for poor connector connection. • Check for misrouted harness. • Check for any accessory parts which may cause electric interference. If a problem is found, repair as necessary. — Verify repair Go to Step 12 12 Substitute a known good MAF & IAT sensor assembly — Go to Step 13 Go to Step 22 13 Replace the MAF & IAT sensor assembly. — Verify repair — 14 1. Using the Tech 2 and ignition “On” and engine “Run”. 2. Monitor the following parameters in the data display. • “Desired Injection Quantity” & “Injection Quantity” • “Desired Injection Start” & “Actual Injection Start” Are the large gap or unstable parameter displayed — Go to Step 21 Go to Step 15 15 Using the vacuum pump and check the EGR valve (if • Restrict shaft movement. Check for objects sticking the shaft, broken diaphragm or excessive carbon If a problem is found, repair as necessary. — Verify repair Go to Step 16 Step Action Value(s) Yes No When idling or part-throttle When accelerated
High Desired Low Time Actual High Low Desired Actual Time Vacuum Pump Small Window |