I've searched all the archives (spent a couple of hours on it), and can't seem to find a definitive answer.

I've got a brand new Digital 6+ that I've had for over 9 months that I can't use because it will not drive the factory tach on my 1991 Pontiac Formula (manual transmission, 305 H.O. TPI engine). I've talked to MSD tech support 3 times on this, and the last 2 times I was told there is "probably" a tach filter that I have to by-pass/splice around in the white wire coming from the distributor. I've also been told this tach filter doesn't exist on all cars. I understand it is a small ( approx. dimensions?) black box or a round cylinder usually mounted on the firewall with a white wire coming in and another one coming out.

I've been all over that firewall and can't seem to find the silly thing. Of course, the everything is so tight in that area I can't guarantee I didn't miss it. Can someone please help me determine if the 1991 Formula's had a tach adapter, and if so, where it is hiding? I hate having this $300 ignition box just sitting on a shelf in the garage. I'd also like to get the MSD working before I install my new 383 in a couple of weeks, if possible.....

Thanks in advance for any assistance anyone provides.

Have a Great Day!

--- Vern (gonna have to edit my signature....)

 

Ahhh... the good ol 'tach filter'

sure. You can stop looking for it now.

Call MSD back and ask them if the tach filter for the 6/6A works with the Dig 6

 

The only time I've seen this problem has been on Pontiac cars. You will need a tach adaptor from MSD. I think it's part #8917 but don't hold me to it. I can't believe the tech didn't tell you this??

 

Do a search for member MSDTECH. Email him. He will help you out.

 

All I had to do was disconnect the tach wire from the distributor harness and plug it into the MSD tach connecter on the MSD Digital 6 box.

Tach adapter? I didn't need no stinking tach adapter, just a female wiring connector and 36 inches of wire.

So why couldn't MSD tell me to try that? Guess I should've thought of that one and tried it a lot earlier in the process....

FWIW - the BVBD (Big Vern Butt Dyno) notices a marked in town normal driving increase, and that's still with the factory coil and standard spark plug gap.

Have a Great Day and Thanks for the inputs!



- Vern

 

Now how are they going to sell you a tach adaptor if you go and figure it out yourself?

 

REALLY!!!!

 

Just put the MSD dig 6+ on my 91 Z28. Put my tach wire to the white wire that comes off the dist. and go's to MSD box(signal wire). Tach works fine. The tach output on the box would work to, but I didn't need to for some reason?

 

Beats the *** out of me! I've heard the Firebirds were the only ones running into trouble, so if yours works that way, GREAT!!!!

I even tried a buddy's remote coil little MSD harness in case mine was bad before I went to running a new wire from the ignition box. My harness was/is fine.

Watch and see if your tach gets crazy over 3000 RPM, that's another symptom I've heard about. If so, try the tach plug on the box. If that fails, you're welcome to buy their tach adapter.

Good Luck!!!!


- Vern

 

It's been like that for at least 2000 miles. No problem's at all.

 

GREAT!!! Glad it's working out for you. I hope mine does too now that I've finally gotten it working.

Have a Great Day!!!!



--- Vern