1G ECMLink tuning and battery voltage dropping

[theface]

1992 Plymouth Laser, engine was built pistons, 274 cams, springs, valves, not sure of piston's for compression ratio. AFPR at 42.5, PTE 880 injectors new 200kms, AEM fuel rail, Garrett 60-1 turbo, FMIC, long intake filter, Walbro 255 with rewire mod, NGK BPR7s, external WG, 3" exhaust back, aftermarket BOV, SD set up 4 bar and IAT with plug and play harness, AEM series x WB, MBC, new tbelt, timing set at 5, boost leaks tested to 35psi.

Runs and idles good, pulls nice and hard after the good old boost lag but seeing the volts dropping down to 12's after a pull down to idle. I changed and had both batterys tested. Changed the alternators and had them tested (had spares).

What am I missing for volts to drop after a pull to idle, and SD table help would be nice I know I have to go thru it and add and - on the tables then smooth it out

 

[steve]

2G ECU's have some control over the alternator output. I'd start by reading the 2G DTM and monitor the control line to see if the ECU is turning the alternator off during coast down.

ecualternatorcontrol [ECMTuning - wiki]

www.ecmtuning.com

From the 2G Tech manual:

GENERATOR G TERMINAL
The engine control module limits the generator output current by duty control of the continuity between generator terminal G and the ground.

When there is no continuity between generator terminal G and the ground (let this be 100% duty), transistor No. 1 (TR1) stays in the always ON state. When the voltage at generator terminal S reaches 14.4 V, the power transistor is forced to OFF to adjust the generator output voltage to 14.4 V. This operation is the same as that of the conventional generator.

When generator terminal G is short-circuited to the ground (let this be 0% duty), the TR1 stays in the always OFF state. In this case, when the voltage at generator terminal S reaches 12.3 V, the power transistor is forced to OFF to adjust the output voltage to 12.3 V. Since the voltage is lower than charged battery voltage, practically no current flows from the generator.

GENERATOR CURRENT CONTROL

During the period the engine is in operation, the ECU achieves duty control of the continuity between generator terminal G and the ground. (In this case, the OFF duty of terminal G is controlled to equal the ON duty of the power transistor in the voltage regulator.)

Operation of the headlights causes a sudden increase in current consumption, but the ECU suppresses a sudden increase in the generator output current, thereby preventing the sudden increases in electric load from abruptly reducing the engine speed while the engine is running at idle. (During the period before the generator generates enough power, the battery current is additionally supplied to the headlights, etc.)

During the period of approximately 0.5 seconds after the power steering pressure switch has been set to ON and also during the period of approximately 0.5 seconds after the selector lever has been changed over from the N range to the D range, the ECU controls generator terminal G in terms of 30% OFF duty to suppress generation of power by the generator.

Under the following conditions, however, this control is not achieved:

High engine speed.
Engine coolant temperature 50°C or lower.
Air conditioner switch ON.
More than 0.5 seconds after the power steering pressure switch has been set to ON.
More than 0.5 seconds after the selector lever has been changed over from “N” to “D”.
Three seconds or less after the engine has been started.

When a high signal at generator terminal FR lasting for more than 20 seconds is input to the ECU during operation of the engine, the ECU determines that the generator terminal FR circuit has been open-circuited and stores diagnostic trouble code (No. P1500) in memory, and places generator terminal G in the always OFF state.

 

[theface]

its a 1g but ,traced it down to just bad alts waiting on a new 90 amp alternator

 

[99dsmer4g63]

its a 1g but ,traced it down to just bad alts waiting on a new 90 amp alternator

This is why having a vehicle profile filled out is so important.

-Daniel

 

[theface]

This is why having a vehicle profile filled out is so important.

-Daniel

in the original post i did say 1992 Plymouth laser , problem with vehicle profile is have multiple built 1g dsm atm that is why i tried to add as much as i could to the original post

 

[steve]

its a 1g but ,traced it down to just bad alts waiting on a new 90 amp alternator

Sorry, You did and I missed that the several times I read it before I came back to reply and push the thread forward.