Tach signal issue with Super Mag.

I know this topic has gone around a few times. I had a perfect working system. SM4 Auto meter shift light tach MSD signal converter. PSI rev limiter. This is a combination that sounded like it might not work but it worked great never had an issue all year. Switched to SM5 mag. installed FIE rev limiter since we put an air retard on the Mag I had to remove the PSI.
Had good tach signal on start up and stage. No issue. Let the clutch out and the tach was going nuts. Had the replay camera in the cockpit. The FIE limiter works because I have bumped it at the 1-2 shift since I have no shift light.
Switched to the FIE tach/signal converter. still having issues Can not get clean signal with the pickup on the coil wire. Also looks like we have noise spiking Fuel pressure. What type shield covering/wrap have you guys used that has helped?
This is a pedal clutch car 3 speed. learning to drive without a tach but would not mind having stage RPM at least. Using RPM data logger. I am using suppression plug wires and ohmed them out... cant find loose wires or any issues yet. I have checked everything I have been advised to. If you have had issues and solved them please let me know what you did.

 

I agree with Mike but ill add that when I was having those problems it ended up being the plug wires. I think it was a matter of them breaking down internally.

 

I have been communicating with FIE. I have checked everything he has advised to check at this point. I checked the ohms on the wires and they check fine and it happened like a switch when I put the new mag on and I was advised the mag change should not matter. I will for sure put new wires on this winter if we don't resolve this another way. thanks.

 

Mike about how many runs would you consider before this might be happening?

 

Invest in a stack tach, There is too much electrical interference"noise" coming of that mag . We had the same issue . Stack tach is impervious to electrical noise is shock mounted and really easy to setup, and change shift points.

 

Thanks for the input. I did put a new coil wire on beginning of this year. Tach runs off car battery, Makita tool battery set up.. New battery also this year. I did not replace plug wires but this issue started with the first run of this year and worked perfect last run of last year. Plug wires had 25 runs beginning of this year.

 

For your tach issue...look at FIE webpage for tech article on build your own rev limiter using the HD FIE relay.It talks about using another crank trigger sheilded pick up straight to your tacho for a clean signal.some info in the article about how to do it.this should solve your tach problem and give you rock solid signal without interferance.

 

Turbo. I have been in contact with spud he sent me a wiring diagram and I am going to try to eliminate the signal converter and try using the Crank trigger for the rev limiter to pick up a signal. Would love to get all those other wires from the signal converter off the car. I just rewired it today. Thanks!

 

i ran a SM5 years ago i ran a inductive pick up off the coil wire for the tach

 

The problem using a pick up of the coil is when you are on the limiter you loose the signal.By using a crank trigger pick up straight to the tacho it will work even when using 2step or 3step limiters.The tacho signal is not turning on and off with your spark.