C.1.3 Examples of Display Groups for Long Term FT Adaptive Value Depending on the year, vehicle, engine, and engine code, you may see some combination of the following long term FT parameters: • ADPVALUEO2(ADD)(%) • ADPVALUEO2(IDLE)(ADD)(%) • ADPVALUEO2(MUL)(%) • ADPVALUEO2(P/T)(ADD)(%) • LEARNO2(ACTUAL)(BANK1)(%) • LEARNO2(ACTUAL)(BANK2)(%) • LEARNO2(BANK1) • LEARNO2(BANK1)(ADD)(%) • LEARNO2(BANK1)(IDLE)(%) • LEARNO2(BANK1)(MUL)(%) • LEARNO2(BANK1)(P/T)(%) • LEARNO2(BANK2) • LEARNO2(BANK2)(%)
160 Fuel Control Learning Adaptation Values Short-Term Fuel Control • LEARNMIXTURE(BANK1)(%) • LEARNMIXTURE(BANK2)(%) Below is atypical display group, Group (32), LEARN VALUES O2”. • LEARN VALUE O2(BK 1)(IDLE)(%) • LEARN VALUE O2(BK 2)(IDLE)(%) • LEARN VALUE O2(BK 1)(P/T)(%) • LEARN VALUE O2(BK 2)(P/T)(%) C.1.4 Important Tips for Long Term Fuel Control • The value typically ranges from -10 to +10. A normal operating engine should fluctuate only slightly. If more than ±7%, perform a mixture diagnosis. Technicians report MAF sensor problems with readings of ±5%. • Use Basic Settings for faster adaptation relearn. Take short road test (usually 2–3 miles) with the scan tool hooked up in Basic Settings. For relearn, make sure the engine is at normal operating temperature (coolant minimum temperature of F C and a maximum intake air temperature of F C. For idle relearn, let the engine idle in Basic Settings fora few minutes. For road test in Basic Settings, perform multiple accelerations and decelerations, as well as apart throttle cruise. Check to see that learn values are back within normal range. If OK, clear the codes. Field technicians report faster relearn and verification of repair by not clearing codes until correct fuel control has been confirmed. Finish by setting all Readiness Codes, and then one more final road test (see Basic Settings and Fuel Trim Accelerated Learning on page 48). • Some vehicles may have part throttle learning divided into 3 different parts (PT, PT, PT. Check to see that each part is in proper specification. • For most systems that have FT control using ±25% maximum range, readings above or below 14 sets a DTC and turns on the MIL. C.2 Short-Term Fuel Control Short term FT is usually called O regulation or O control. The readings are constantly changing, directly responding to OS input. Normal readings usually are in the ±10% range with 0 as the midpoint. If it gets too far off, Long-term additive or multiplicative adjusts the window back to the midpoint (balanced state). C.2.1 Examples Short Term FT O Regulation Depending on the year, vehicle, engine and then engine code you may see some combination of the following short term FT parameters: • ADPVALUEMIXTURE(BANK1) • ADPVALUEMIXTURE(BANK2) • ADPVALUEMIXTURE(BANK2)(%) • ADPVALUEO2
161 Fuel Control Learning Adaptation Values Short-Term Fuel Control • LEARNVALUEO2 • O2CONTROL(BANK1)(%) • O2CONTROL(BANK2)(%) • O2CONTROLFACTOR(BK1) • O2CONTROLFACTOR(BK1)(%) • O2CONTROLFACTOR(BK2) • O2CONTROLFACTOR(BK2)(%) • O2REGULATION(BK1-SNS1)(%) • O2REGULATIONBEFORECAT(%) • O2SENSOR(BK1-SNS1)(V) • DYNAMIC FACTOR O2-SNSBEFORECAT • O2CONTROL(BANK1)(%) • O2CONTROL(BANK2)(%) • O2CONTROLDEVIATION(%) • O2INTEGRATOR Below is atypical short term FT display group, Group O REGULATION BEFORE CAT • O2 SENSOR(BANK BEFORE CAT)(V) • O2 SENSOR(BANK BEFORE CAT)(V) • O2 REGULATION (BANK 1)(%) • O2 REGULATION (BANK These parameters are equivalent to the short term FT correction during closed loop operation. This correction is based on the OS input fora given engine load and speed. The ECM monitors engine operating conditions and calculates short-term and long-term adaptations to correct for engine wear. The value typically range is ±10. A normal operating engine should see this value fluctuate by at least 2%. If it fluctuates by more than 7%, perform a fuel mixture diagnosis. NOTE: i Some vehicles use a calculated value called factor. The parameter names are ADP VALUE O and DYNAMIC FACTORO2, SNS BEFORE CAT. Normal range is 0.5–1.5; 1.0 ±0.3 is base midpoint for L (AAA, the range is Positive values indicate the ECM is enriching the air/fuel mixture, and negative values indicate the ECM is leaning the mixture. During open loop operation, the ECM runs at abase program without correction and the parameter displays a fixed 0% value. The ECM adjusts the air/fuel mixture by changing the fuel injector pulse width. C.2.2 Important Tips for Short-Term Fuel Control • On some OBD-I (1991–1995) vehicles, values for short term FT, LEARN O (IDLE, LEARN OPT, or LEARN O (FULL, maybe mislabeled as reading in percentage. In actuality, they are reading a numeric factor of 1.0 midpoint ±0.5 (0.5 to 1.5). For L AAA engine, the range is 0.80–1.20.
162 Fuel Control Learning Adaptation Values Oxygen Sensor Voltage • Range: 0.5 - 1.5 Normal Value 1.0 ±0.3 (0.7–1.3) is base midpoint • For L (ABA) IDLE ADAPT 0.87–1.2 • For L (AAA) IDLE ADAPT 0.53–1.47 •