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Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
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You don't have one. The only MN12s that had one were the SCs.
 

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Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
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9,517 Posts
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.
 

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108 Posts
Discussion Starter #5
Great, thanks for the info. Looks like I need to start testing more sensors than I thought. My timing isnt moving.
 

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Super Moderator
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5,115 Posts
There's one thing to check FIRST - check the SPOUT connector. If it opens up (or if the plug is missing), you'll be fixed at 10* BTDC.

RwP
 

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Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
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9,517 Posts
What do you get if you measure for voltage across the connector?
 

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Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
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9,517 Posts
Sounds off to me, it should be a clean signal. Do you have the EVTM? Time to do some pinpoint tests for a short.
 

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Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
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9,517 Posts
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