Diagnostic Aids

A faulty TP sensor or TP sensor circuit can cause VCM to incorrectly calculate predicted mass airflow value. Observe throttle angle with throttle closed. If throttle angle is not zero, check for throttle plate sticking or excessive deposits on throttle plate or throttle bore, TP signal circuit shorted to voltage, or for poor connection or high resistance in TP sensor ground circuit. If a problem is not found and TP sensor angle at closed throttle is not zero, replace TP sensor.

Inspect VCM connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connection. Inspect MAF sensor harness routing to ensure it is not too close to high-voltage wires such as spark plug leads. Inspect wiring harness for damage. If harness is okay, observe scan tool while wiggling MAF sensor related connectors and wiring harness. A change in display will indicate location of fault.

A Wide Open Throttle (WOT) acceleration from a stop should cause mass airflow displayed on scan tool to increase from about 4-7 gm/s at idle to 100 gm/s or greater at 1-2 shift. If mass airflow does not indicate as specified, check for a plugged intake air duct or dirty air filter element. A skewed MAP sensor can cause BARO reading to be incorrectly calculated. To check MAP sensor, compare BARO reading on vehicle being diagnosed to a BARO reading on a normally operating vehicle. If a large difference is noted (over 8 kPa), replace MAP sensor. This may cause abnormally high IAC counts. If a comparison vehicle is not available, check IAC counts with engine running just off idle. If IAC counts are high, replace MAP sensor.

IF DTC P0101 can not be duplicated, FAIL RECORDS data can be useful in determining vehicle mileage since DTC was last set. This may determine how often DTC sets.