MSD grid revlimiter false trigger

[Mike Graham]

Any grid experts that can clue me in on revlimiter false triggering?
Rev limiter coming on intermittently in high gear
Shift light also triggers at wrong rpm.

[Dave Ficacci]

Originally Posted by Mike Graham

Any grid experts that can clue me in on revlimiter false triggering?
Rev limiter coming on intermittently in high gear
Shift light also triggers at wrong rpm.

Where in high gear? I had to ramp my high side chip 600 rpm higher than where I actually wanted to set it so it won?t come on prematurely . Msd said my distributor was no good, even though it was a brand new MSD distributor. Then they said my cam gear must be no good?

Do you see the trigger pulses in your msd review data file?

In their defense, they benched tested my grid and distributor in their rig and it worked perfectly.

[cad]

Not sure if relevant, but....here are a few notes acquired from info over on DRR....

To Shift Gears using RPM, use the Settings /Gear Shift tab and program the Launch Delay to a value slightly LESS than where the gear shift would initiate. This will keep the Grid gear counter locked into 1st gear in the event you loose traction and peddled the car. It will NOT recognize the RPM drop as an actual shift. The RPM Drop is the amount of rpm drop at ANY given time while in that gear for the Grid to move the counter to the next gear. In the Settings/ Shift Light tabs program the shift rpm for each gear listed. Every time the ignition is turned on it?ll output a ground signal on the Yellow wire for 3 seconds. To disable this function change the Power-ON Test to OFF. This RPM Shift output comes out of the Yellow wire as a (-) ground signal.

The Output Switch is a ?DELAY TIMER? that has a window switch or hysteresis RPM feature. I suggest using the Output Switch to shift with when wanting to shift using a Time Delay ONLY, and if the Shift Light function is available. If the Shift Light is being used for another function, the RPM Switch feature of the Output Switch can be used, but should be programmed together with the Time Switch to limit multiple RPM activations when not desired.

[cad]

In the REV LIMITER / SETTINGS tabs, the Safety Run-Time uses a default setting of 12.5 seconds. I recommend leaving this setting during initial set-up. The Safety Rev Limiter has a default setting of 2,000 rpm. This value should be raised to 3,500 rpm. The reason for this is that the engine will be rpm limited to this value while shutting down and driving back from the end of the track. To disable this feature, enter an rpm value that is the same or greater than the ?Maximum Rev Limiter? setting. To Tune this feature to the best settings, reduce the Safety Run-Time by 0.5 seconds every run, until you see activity in the ?Rev Limit Active? channel in Data Acquisition during the run shutdown. When this activity is achieved in the display, return to the previous Safety Run-Time setting. DO NOT use a Safety Run-Time setting ?Less Than? your elapsed time plus 1.5 seconds. Example?. A 9.00 et car should not have a finished programmed setting of less than 10.5 seconds in this example. You want the ignition to fire every pulse unlimited during a ?normal? shut down.

[Dirk Olson]

Originally Posted by cad

Not sure if relevant, but....here are a few notes acquired from info over on DRR....

To Shift Gears using RPM, use the Settings /Gear Shift tab and program the Launch Delay to a value slightly LESS than where the gear shift would initiate. This will keep the Grid gear counter locked into 1st gear in the event you loose traction and peddled the car. It will NOT recognize the RPM drop as an actual shift. The RPM Drop is the amount of rpm drop at ANY given time while in that gear for the Grid to move the counter to the next gear. In the Settings/ Shift Light tabs program the shift rpm for each gear listed. Every time the ignition is turned on it?ll output a ground signal on the Yellow wire for 3 seconds. To disable this function change the Power-ON Test to OFF. This RPM Shift output comes out of the Yellow wire as a (-) ground signal.

The Output Switch is a ?DELAY TIMER? that has a window switch or hysteresis RPM feature. I suggest using the Output Switch to shift with when wanting to shift using a Time Delay ONLY, and if the Shift Light function is available. If the Shift Light is being used for another function, the RPM Switch feature of the Output Switch can be used, but should be programmed together with the Time Switch to limit multiple RPM activations when not desired.

The problem I have is that 1st to 2nd and 2nd to 3rd shift light work just fine but 3rd to 4th shift does not come on. The rpm drop and the timer have remained the same . Anybody else have this issue?

[Mike Graham]

Originally Posted by Dirk Olson

The problem I have is that 1st to 2nd and 2nd to 3rd shift light work just fine but 3rd to 4th shift does not come on. The rpm drop and the timer have remained the same . Anybody else have this issue?

I have had this in the past. I was caused by rpm drop causing the grid to think it was already in the next gear. See above.

[Mike Graham]

Originally Posted by Dave Ficacci

Where in high gear? I had to ramp my high side chip 600 rpm higher than where I actually wanted to set it so it won?t come on prematurely . Msd said my distributor was no good, even though it was a brand new MSD distributor. Then they said my cam gear must be no good?

Do you see the trigger pulses in your msd review data file?

In their defense, they benched tested my grid and distributor in their rig and it worked perfectly.

I don't see any trigger pulses. only see the rev limiter coming on. It starts about the rpm that I have my shift lite set to. I aslo see short spikes on the shift lite graph. I have launch delay set out and shift delay. This is something new. It has worked before. Started acting up in eliminations last weekend and got worse every round