No Tach Signal from HEI

[jonah]

Hi,

I am very new to MS, so I just wired up the IAT, CLT, MAP, LC-1 wideband O2 and OPTOIN for a tach signal to the Microsquirt v3 on my Buick 4.1 V6 so I could get some readings and get familiar with TunerStudio.

I am currently running a holley projection 2D, when I start the motor the IAT, CLT and MAP seem to work correctly. The LC-1 wideband O2 read erratically but I read that it won't read correctly without RPM signal(or it could just need calibrating) but the real problem is I am getting no RPM in TunerStudio. I also had the tachout from MS connected to an aftermarket tach and that read nothing as well. If I connect the aftermarket tach directly to the HEI tach port it works normally. It is wired with OPTOIN+ going to the HEI tach port on the cap and OPTOIN- connected to 12V.

Am I missing something? I have been reading and see that people have problems with the HEI signal being unstable but I am getting nothing.

Thanks in advance for helping a noobie!

[jonah]

Update, I tried to ground the OPTOIN- and got nothing.

I then spliced into the hall sensor that runs the Holley Projection, The signal wire from the hall sensor went to OPTOIN+ and the OPTOIN- was grounded. At idle it did nothing, when rev'd up it the RPM guage in TunerStudio did a couple of blips, so fast I couldn't read the number.

I think I must have some setting wrong in TunerStudio.

[jonah]

Update:

So just to see if I could get anything moving I disconnected the OPTOIN connections and hooked up a spare VR sensor (in an old HEI distributor) to the VR-1 leads. I spun it up and nothing. The TunerStudio tach doesn't even twitch. I am at a loss, is it possible I have a bad microsquirt?

Any input would be appreciated.

[Bernard Fife]

Jonah,

What you should do depends on which version of MicroSquirt you have. If you have a V3 MicroSquirt, OptoIN- should NOT be grounded. It should be left 'floating'. You do that by snipping the lead off, and taping it up so that it is not connected to anything at all.

You may also have the ignition settings wrong, so you'll want to post the MSQ file of your settings, and also a datalog of a starting attempt could be useful when sorting this out.

Lance.

[jonah]

Thanks for the input. I have been learning a lot over the past couple of days.

I switched to the 3.2.5 firmware (from the B&G 3.77) and everything (well almost everything) started working. The tach signal is coming in on the VR1 circuit from the tach out on the HEI. I am not sure if I should be on the OptoIn circuit instead, I think the Tach out only spikes to 12v so I think it should be fine. Once I have fuel dialed in a bit I am switching spark control over to the MS so that will all change soon. Anyway, I have RPM after adjusting the noise filters and the wideband (lc-1) started reading normally. It started right up and is currently running 13:1 at idle without doing anything else.

Only thing I can't get now is my F-Idle solenoid (on/off) controlled by a relay isn't kicking on when it is cold.

Time to start tuning now!