MS3/HEI7 Trigger Adv and Crank Adv Problem

[91blkvette]

Despite using both the 10 degree (where it is now) and 60 degree pickup coil alignment settings, cannot get the cranking advance to move from 5 degrees btdc (bypass disconnected).

Trigger angle moved from 10 to 15 degrees...no change in crank adv

Trigger angle moved from 60 to 90 degrees...no change in crank adv

Also noticing the NO SYNC box is red. Before uploading vers 1.3.2, MS3 sync'ed.

Reading and re-reading, verifying and reverifying... same result, no change. One week and about 50 hrs now...

Suggestions?

[91blkvette]

Using MS3/MS3X not just MS3....

[jsmcortina]

Please see the RELEASE-NOTES.txt that are supplied with the firmware.

It sounds like your ECU isn't actually controlling the timing of the HEI7 module.
Either the EST signal isn't getting through or bypass is stuck in the wrong condition.

Check your wiring for those signals and also...


James

[91blkvette]

Please see the RELEASE-NOTES.txt that are supplied with the firmware.

It sounds like your ECU isn't actually controlling the timing of the HEI7 module.
Either the EST signal isn't getting through or bypass is stuck in the wrong condition.

Check your wiring for those signals and also...


James

James, Quick question (to which the answer may be the root cause of my problem) .. I'm running my MS3 in parallel with my Corvette ECU, so on which side of the bypass would I wire in the MS3? Does it make a difference?

[jsmcortina]

The HEI7 module bypass input needs to connect to the MS3 only.

James

[91blkvette]

The HEI7 module bypass input needs to connect to the MS3 only.

James

the instructions (followed the attached diag) for MS3X for HEI7 has the bypass (B) wired to SPK B on the MS3X. The Dist Ref (R) connects to pin 24 on the MS3. So I have the ECU wired wrong?

[jsmcortina]

The HEI7 module bypass input needs to connect to the MS3 only.

James

the instructions (followed the attached diag) for MS3X for HEI7 has the bypass (B) wired to SPK B on the MS3X. The Dist Ref (R) connects to pin 24 on the MS3. So I have the ECU wired wrong?

Have you followed that diagram or not? I'm confused now.

In your previous post you mentioned about connecting to the stock ECU as well. That would be a problem if R is connected to both ECUs.

James

[jsmcortina]

Still

[91blkvette]

Still

Log is with R pin connected to factory ECU. Have seen spikes as high as 29K at cranking speeds. Adjusted noise settings and significantly reduced spikes (at cranking speeds). Not able to get the engine to start properly to create a running datalog.

The HEI7 has been replaced by a HEI 8 MSD 8366 distributor, and the MS3X is wired according to instructions ( bypassed factory harness entirely). MS3 wire 24 ( R wire) connected to the factory ECU also to enable support factory control of fuel pump, cooling fans and 700R trans control.

Previously, R pin to factory ECU not connected, and MS3 controlled fuel pump, but no cooling fans were controlled. Never got past the running timing confirmation problem due to the cooling fan issue. Nov msl attached.

Understand MS3 can control all the above ( wiring for cooling fans in place in anticipation). Hoping to minimize additional work and problems.

[jsmcortina]

You may be best off using the "tacho output" on "Tacho" from the MS3X to feed the stock ECU. This should mimic the signal the stock ECU is expecting and by keeping the R wire to the MS3 only there will be no interference.

James

[91blkvette]

You may be best off using the "tacho output" on "Tacho" from the MS3X to feed the stock ECU. This should mimic the signal the stock ECU is expecting and by keeping the R wire to the MS3 only there will be no interference.

James

James, so to confirm, I should NOT be trying to connect R wire to both the MS3 and the factory ECU? According to what I've read on a Corvette forum, the ECU needs the dist ref pulses to energize the fuel pump relay, and to support engine start....

"The distributor will send a string of pulses to the ECM (Engine Control Module) in response to the engine being rotated by the starter. These pulses continue as long as the engine turns (both starting and running) and if they are not present, the engine will not run."

This is why I tapped pin 24 to send the signal to the ECU ( it is controlling fuel now). Trying to run a "piggy back". I know other C4 Corvette owners are doing this ( but probably using MS1 or MS2). But if I can't using a MS3/MS3X, I'm ok with this and will work around the factory ECU. Thanks for your reply.

[jsmcortina]

The tach input circuit on the mainboard is the same whether you use and MS1, MS2 or MS3. So if they are able to share it, you should too.

Don't you like my idea of using the tacho output?

James

[91blkvette]

The tach input circuit on the mainboard is the same whether you use and MS1, MS2 or MS3. So if they are able to share it, you should too.

Don't you like my idea of using the tacho output?

James

Ok..the light bulb just came on. Connect Tacho Out on MS3X to the factory ECU dist ref input.

Then this begs another question as to sharing Tacho Out when using a MSD 6AL ( have one to install). Have I now created another sharing problem?