Join Date: Jan 2009
Location: North Ridgeville, Ohio
On my 97 (will be different but most likely very similar on yours) timing is controlled by volumetric efficiency (MAF sensor/RPM relationship) and RPM. Essentially - at x RPM, command y degrees of spark while at z load. There are modifiers to add or subtract timing based on coolant temperature, intake air temperature, open/closed loop (commanded A:F ratio), and EGR flow. There are also functions to reduce or limit timing under certain conditions, e.g. throttle tip in or idle.
All the sensors involved would include MAF, CKPS, IAT, ECT, TPS, DPFE and VSS.
Primarily the PCM commands timing based on the lowest value found in a number of tables with engine load on one axis and engine RPM on the other axis, after applying modifiers for operating conditions (EGR, Temps).
Again - this is the EEC-V method. I don't know how much applies to the EEC-IV.
97 Laser Red Thunderbird LX 162k,
Stage 2 4.6L 2v N/A | 300 BHP (255 RWHP, 290 RWTQ) | 13.95 @ 97.58
| Build details | Pics at the Lorain Assembly plant
98 Black Mark VIII
160k, stock daily driver
07 Redfire Fusion V6 SEL
178k, for the wife
Gone but not forgotten:
96 Mark VIII, 94 Cougar XR7, 93 Mark VIII
TCCoA's resident pilot since 2014
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Last edited by theterminator93; 07-15-2014 at 08:14 PM.