ndaniels

Have a tach issue that has devolped in my new to me 21...

First question- from what I've found everyone says you have to run a msd 8910 tach adapter on 454/502 mag motors when you're using the wiring harness that is made for them?

When I bought the boat the tach was bad, found a replacement and turned out it was bad too- so I'm currently using my quicksilver tach outta the 24Super. I'm also running a LM-2 o2 sensor because I'm paranoid about afr- it also has a rpm input for dataloging.. that was working fine up untill a couple of weeks ago and at the same time, I've noticed that the tach is off for a while on startup when cold- reads high like its getting the multiple spark input for a few minutes. Then it settles down to where its supposed to be and reads correctly... the lm-2 is way off, reads high all the time and I know that these are sensitive so I think the tach adapter is bad.

I've seperated all the wiring and inspected- everything looks good. When the tach adapter is unplugged, makes no difference in anything. I've also hooked the tach signal wire from behind the dash directly into my lm-2 to isolate it from the tach same thing. The grey signal wire out of the msd isn't hooked up to anything- I think this is normal on this setup from what I can find? It just uses a 4 wire connector behind the motor- 2 are for the tach adapter and the others are for spark, right?

My setup apparently came from teague, have the recipt, and has the wiring harness, msd 6m2, and a 8910adapter.. I added the soft touch rev control but currently am not running pills while verifying the ecm settings and deciding wether it needs some tweaking.

Sorry for the long story, but anyone have some experience with mag motors and these tach adapters? This is hooked up way different than my carb motor, but was working- I think the adapter crapped out on me and the quicksilver tach isn't as sensitive as others, so it works for the most part.

I can try calling Teague Monday and see if they have any ideas... getting new instuments for the boat and would like to be able to get this figured out before I install them.

Thanks guys!

ndaniels

Also the wiring is really alot cleaner than this normally... its a photo after I pulled everything apart while working on it.

ndaniels

From what I've read you have to use the tach adapter when the msd is triggered from the white wire?... since nothing changes when I unplug mine, I'm going to bet money its bad and will buy another one ($30-40).

Hopefully this solves my tach signal issues.