Ok in my car I installed an MSD 6A box. I used the wire adapter MSD suggested. The instuctions say to bypass the tach filter. I did a search and found that the tach filter is a little 1.5 inch black box on the firewall. My tach would go up to 3000 RPMs then start bounching and go back to 0 intil I let off the gas then it would be normal. Well Since I couldnt find my tach filter I cut the tach wire and put it into the terminal on the back of the MSD box. this worked better but not completely righ. The tach will now read upto 5000 RPMs then it will do the same thing... start bouncing and go down to 0 until I let off. I can live with this because its very rare I will accelerate upto 5000 rpmss but i still like everything on my car to be right. In my searches I found that some cars come with a filter and some do not... its hit or miss. Does anyone know for sure if my car comes with a filter or not specificly.... its an 89 2.8 firebird with an auto tranny. I dont see a little black box on the firewall but could there be a different type. .... maybe an inline filter that is in the harness way down where I wouldnt be able to see it or one built into a circuit board in the computer? Does anyone have the Helms manual for an 89 v-6 diagram of the tach wire? My chiltons just doesnt cut it. Also can someone who has a tach filter take a pic of it and post it, so I know exactly what I am looking for. Now if my car doesnt have a filter and I did re route my wire to the tach termanial... what is causing the problem with my tach. this didnt start until I put the MSD box in so unless its an amazing coincidence.... I know its to do with installing the box. I didnt have any problem when I installed it on my old 85 firebird. Any ideas... Do I have to shield my tach wire from all the rest of the MSD wires?

 

Did you cut the wire in the MSD box so it is for a 6 CYL? I dont know if that wire has to do with the tach at all just a guess.

 

No I didnt, I didnt even know there was a wire as I bougt a used MSD 6A box and it didnt come with instructions. Where is this wire? ... I do vaguely remeber from the last time I install a box on a V-8 and didnt need to cut any wires now that you mention it. Thanks! I know MSD has a web site with these intructions on it. Anyone know off hand what the web site is?

 

go to http://www.msdignition.com/

and type in "installation instructions" into the search box it will bring up exactly what you are looking for

 

Ok I looked at the instructions and it says the 6a doesnt even have the wire to cut and will work with V-8's V-6's or 4's without modifcation. The only thing is it said it will work with even fire V-6's and for odd fire v-6s it needs an adapter. What is my 2.8L v-6 and even or odd fire .... actually what is an even or odd fire V-6? It did say to bypass the filter but I can find one on my car so I dont think it ever had one. The last thing the instructions said if all else fails I will have to buy the tach adapter part number 8910

 

Before you buy that tach adapter, try what I did on mine:

1. Disconnect the white wire in the car's wiring harness going to the tach near the distributor. I had a nice grey connector that made this really easy on my 91 Firebird.

2. Run a wire from the tach output on the MSD box and splice it into the tach side (not the distributor side) white wire so the box feeds the tach instead of the distributor and coil.

Worked like a charm and saved having to buy the MSD Tach Adapter they were telling me I needed. Liars!!!!

 

Now Vernw, you know these companies will try to drain every last penny they can from you.

 

Well, it sure looked like it in this case, Trickster!

(And I'm not even sure any of us need the MSD boxes with an HEI setup, but I fell for that one too)

 

Ok thanks for the help... I will certainly try that!!

 

ive been having the same problem with no luck. ive got a 6a box on a 92 firebird 3.1. i cant find my filter box either. it jumps around from 4 grand and up.

 

I have a 6 AL on my 91 3.1 and have no problems. Only thing i know is the 6AL has a rev limiter and rubber mounts which is a waste of money for the extra 30 bucks. If i remeber i think the wieres were under a black screw or black popout thing on the side. It has been years since i put mine in but check that out.
Also did you get the wireing harness that makes hooking it up 1000 times easier.

 

Actually I think the rev limiter & vibe mounts were a great deal for only $30 more. The vibe mounts themselves are about $20 if you try to buy them separately!

I do agree that with our HEI's, we don't need the MSD box. I have one (the 6AL) and didn't notice any improvement. I actually noticed a de-improvement- my car used to start with a 1/2 second crank of the starter. Now it's closer to 1 second of crank time. But it's still pretty damn fast... I know I'm bitching about a 1/2 second, but when you've started the car that way for 8 years, it's a hard habit to break. I kept letting off the key early.

I noticed the best improvement with "just" an aftermarket high-voltage coil. I think an MSD box might show a boost if someone's ignition system was already out of whack- but with a rebuilt distributor, correct timing, and good plug wires/cap/rotor, an aftermarket high voltage coil is the best bang for the buck.

Oh and we're "even fire" V6's, by the way... don't worry about the even/odd fire section of the instructions.

 

The odd fire V6 is any V6 that fires differently than normal. Most notably the Buick odd fire. It was the 3.8L like those used in the Regals and such but it had a really odd firing order, hence odd fire. I don't even remember what it was as I've only worked on a couple and that was long ago.

 

DUDE your answering a question from 2004

 

I just joined the board yesterday, and only because I needed the info on the tach filter. Still didn't help though.