MS-3 2110 Buildup

[trbugman]

I've had LS2 D585 coils running wasted-spark COP for half a year, sequential now. The only problem I had was a starter kick back every once and a while when cold, even with the recommended settings. My voltage calibration was off and the ECU thought that it was lower than it was and was giving too much dwell.

Remove power from the coils and go into test mode and check if your getting 5v to the coils from the ECU.

[Max Welton]

Remove power from the coils and go into test mode and check if your getting 5v to the coils from the ECU.

No 5v.

Max

[trbugman]

Then you need to start looking further back. Do you have 5V at the output ECU? Are both of the ribbon cables attached and fully seated to the MS3 and 3X boards?

[Max Welton]

Mario did the mods I wanted and I haven't had the enclosure open. We're now checking all the settings.

Max

[Max Welton]

So this afternoon Mario spent a bit of time remotely correcting things in my setup until we believe we are getting a correct signal on the pin I am using to drive coil-1. Still no spark.

To review. The engine is on a test stand using a regular 12 volt battery. All the ground pins from the MS and the expansion board are ganged up and grounded to the engine case (excepting the sensor return which is pin #7 on the main connector). With a digital volt-meter I read a noticeable value between the sensor return and pin 14 from the expansion board. This would be an average given the type of meter, but a noticeable signal nonetheless. I also measure ~5 volts between sensor return and the 5 volt reference line from the main board,

The coil is wired up like this with "A" on the right.
A = chassis ground.
B = sensor return
C = pin 14 (coil A drive)
D = +12 volts switched from the battery

All of these I verified with a volt meter at the cable ends.



I have also verified continuity of the plug wire and the plug is well grounded against the case and visible. If there is a spark I will see it.

Now Mario thinks I should be able to get the LS2 to spark by applying and removing the +5 volt reference to C. No joy. I repeated that with the other three with the same result.

Is this a workable way to get an LS2 to fire? I'm having a hard time believing four new coils are bad out of the box.

Max

[trbugman]

Your wiring looks good.



Red 12V
Yellow 5V
Black sensor
Black Ground

If you have 12V and ground to the coil and pulse the 5V it should spark.
You could try disconnecting the sensor ground, it isn't needed for the coil to work. Grasping at straws here.

[Max Welton]

Is there any meaningful test I could do in terms of measuring resistance between coil pins?

Max

[Max Welton]

These coils, they look pretty solid with everything potted. But I'm embarrassed to say they fell off my bench while I was unpacking stuff. About 4 feet. I think I may have killed them. Still hard to believe all four would be casualties. I'd still like to verify somehow before I order replacements.

Max

[Piledriver]

I don't think they are that delicate...
You are still bench testing, right?

I recall another lister having absolute fits with getting his ls2 coils to fire until he realized the grounds of his test rig were not quite all tied together...
(including the hv side)

I run the LS2 coil power grounds to the engine tin, no sense bringing it home to the ECU... and short high power grounds are happy grounds, or at least lousy antennae. Everything else comes home to the ECU mounting plate.

[Max Welton]

The longblock is still bolted to my test stand where I verified function of the hidden VR sensor and good cranking oil pressure. No intake, no alternator. Just the longblock, starter, battery and a couple of switches. I am powering the ECU through the switch that normally controls ignition power.

The plan is to work all the bugs out of the engine ignition system before moving on to the intake and fuel system. Everything will be ironed out on the test stand (including the relay board I'm not using yet) before I go anywhere near the car.

Max

[Max Welton]

So what were the OEM applications of the LS2 coils? I'm going to see if I can get one over the counter (or from the local salvage yard) to play with.

Max

[Max Welton]

Interesting. Forth post into this thread are lists of vehicles that used LS1 and LS2 coils. I think a visit to the local yard is in order today.

http://www.ka-t.org/forums/viewtopic.php?t=55488

Max

[Dtjaden]

Max,

When you state that pin B is a "sensor return" does that mean it is routed to an MS3x ground?

That is what it should be, grounded to the common MS3 grounds. This is the way I have my LS2 coils connected and they work fine.

A - engine ground
B - MS3 ground
C - pin 14
D - switched 12 V+

[Max Welton]

Pin #7 on the Lower 'V3 / Mainboard' connector.

http://msextra.com/doc/ms3/hardware.html#wiring-ms3x

Max

[Piledriver]

That's the sensor ground... all the grounds tie together at the board under the connector, so it's probably OK.
I would personally use a different ground wire for switching/control signals...