Autometer tach reads double

[vstol]

I have a LS-3/427 with an Autometer tach and the Autometer LS adapter for the tac (9117/9123) and the tach shows the idle to be 1900 when in fact it is 980. What did I miss? I thought I had set the tach right I believe it was 4 cylinders and it is a huge effort to get it back out so I would like to avoid that. thanks

[GregWeld]

Originally Posted by vstol

I have a LS-3/427 with an Autometer tach and the Autometer LS adapter for the tac (9117/9123) and the tach shows the idle to be 1900 when in fact it is 980. What did I miss? I thought I had set the tach right I believe it was 4 cylinders and it is a huge effort to get it back out so I would like to avoid that. thanks

I'm laughing at this because if it's set to 4 cylinders and getting a signal from 8 then sure -- it would read double.... But the LS standard output is a 4 pulse - but the tach adaptor kicks it to 8.... So my guess is --- you needed to set the tach up for 8 cylinders - and allow the adaptor to do it's job.


You might need to read this "fix" twice to understand it -- I did. Basically it's an issue of you used the adaptor - thus outputting a 8 cylinder signal and the tach is set up (per what you said) to read 4 cylinders....


https://www.autometer.com/resources/...faq_view/id/77

[vstol]

Greg SOB, totally agree and what is confusing I did not reread the FAQ that you sent.. actually I read it several times before I set it up and probably had a senior moment. I will give it a go as it will be some ass pain getting to it. Thanks

[GregWeld]

I hope that's all it is -- but it made sense that using the ADAPTOR giving the TACH an 8 cylinder signal -- that it would read double with it (the tach) set on 4 cylinders.

My question was - in that case - why do you need the adaptor - if you could just set up the tach with 4 cylinders selected..... That's why I read it twice - to see if I missed something there...

Hope that's all it is - but it looks like that's the mismatch.

[vstol]

The adapter made it plug and play. I tried it the other way but no luck. Now I am trying to find how to set up the tach (pins) for 8 cylinders in the back of the tach. I do not believe they make them that way anymore since this build has gone on way to long.

[waynieZ]

I'm going to subscribe to this because senior moments have become a big part of my life now a days. Now what was I going to do with this????

[gnx7]

When trying to adapt to factory gauges on the RX-7 we use one from Dakota Digital. http://www.dakotadigital.com/index.c...126/prd126.htm

Speedhut also makes kick ass gauges that are GPS based for speedo!

[vstol]

Fixed it just had to change the Tach back to 8 cylinders. Thanks for your help.

[GregWeld]

Shoulda called me first!




Glad that worked!!!

[randy]

when i had mine set to 8 cylinder it wouldnt read past 5k rpms. I had to switch mine to 4 cylinder and use a pull up resistor. Resistor on the power wire going to the gauges to the signal wire going to the tach.