Tacho problems after installing the ignitor/ flame thrower coil

[maverick1]

hey everyone,
I have a 88 Mav 4.2 petrol. I installed a ignitor and flame thrower coil last week and when I installed it, the tacho started bouncing. I contacted the place where I brought and they told me to buy a 10k, 15k, 20k resistor and try that inline. I did that and none of them worked. It is just the standard tacho and I didn't have any problems before installing it. I need it to work as I want to do some carby work on it and need the idle and revs to be right.

The wiring is:
positive coil: red ignition, red from ignitor, black white from engine
negative coil: tacho, and black wire from ignitor.

Any suggestions would be great thanks.

[Finly Owner]

I have no idea what that coil is, so i am going to ask some basic questions.

Does this coil emit a larger pulse of spark? Did they tell you to becareful of you electronic tacho?
Most Tachos depened on coil spark for timing, if the spark is to strong, you may fry your tacho is my guess.

A more savvy person will correct me if Im wrong


Tim

[Yendor]

What model ignitor are you using Pertronix?, 1 or 2?

I guessing by your connections at the positive side of the coil you have removed the ballast resistor?

On the old coil did you have one of those old style capacitor (just like a condenser, silver metal cylinder shape with 1 wire going to it) connected to the negative side of the coil? is that still connected?

Did you remove the original factory resistor for the tacho?, what colour is the tacho wire at the negative side of coil? yellow with a black trace or blue?.

When you tried the 3 resistors inline, you disconnect the tacho wire and connected one side of the resistor to this wire and the other side of the resistor to the negative side of coil? yes?

Sorry for all the questions but it will help.

I have heard a few bad reports regarding the flame thrower coils.

If it was me I would do away with the flame thrower and fit a GT40R coil along with the ballast resistor and keep the ignitor.

[timbar]

dont know if this helps ???

[maverick1]

Finly: Hey thanks for posting. The flame thrower is a higher voltage but I have been assured by the person who sold me it, that it would not do that to my tacho.

Yendor: Thanks so much for your helpful q's. I was told to bypass the ballast resistor totally. The little capicitor is still there but its not connected to the coil at all. I don't know where the original resistor is.... could you help me with this? The tacho is a yellow with black trace and this is connected to a harness joiner where it runs to a blue wire like timbar's picture below. I did connect the resistors like that. The guy I brought it off said not to use Bosch cause even apparently Bosch themselves said not to use them with the ignitor system. Apparently they eventually burn them out. Its strange though, cause on the paperwork with the ignitor it says you can use it...... Anyway if you can help locate the factory resistor that would be great....

Timbar, thanks heaps for the pic. Mine looked similar to this before I put on the flame thrower. Can I ask though, the black capacitor wire you have there, is it connected to the positive side of the coil?

[Yendor]

Yendor: Thanks so much for your helpful q's. I was told to bypass the ballast resistor totally.

If you are running a Pertronix 1 ignitor and have the 3 ohm flame thrower coil you will need to run a ballast resistor other wise it will melt the ignitor, apparently the Pertronix 2 ignitor can be used without the ballast resistor.

The little capicitor is still there but its not connected to the coil at all.

I would connect the capacitor to the negative side of the coil and then recheck tacho operation, if still no good then retry the 3 resistors.

I don't know where the original resistor is.... could you help me with this? The tacho is a yellow with black trace and this is connected to a harness joiner where it runs to a blue wire like timbar's picture below.

If this harness connector is brown, has the Blue and Yellow with black trace wire going into it and is a fair size, this will be the resistor.

The guy I brought it off said not to use Bosch cause even apparently Bosch themselves said not to use them with the ignitor system. Apparently they eventually burn them out. Its strange though, cause on the paperwork with the ignitor it says you can use it...... Anyway if you can help locate the factory resistor that would be great....

That's strange running the GT40R with resistor is the same set up as the one in timbar photo except he is running a standard coil

[maverick1]

Yendor: thanks so much for you help. I tried connecting the capacitor to the negative side and it wouldnt start, so I won't be doing that again! It must be the 2 one then, but the box doesn't say it! I have located the factory resistor and will try to disconnect that and fit the resistor inline. It is a 2.2 k. When I unplugged it today it wouldn't work at all. So I'll let you know how I go tomorrow.
cheers

[Yendor]

Sorry mate, that's all I've got.

It's strange that the vehicle would not start with the capacitor fitted, I was hoping this would filter the signal to the tacho.

I don't think removing the original tacho resistor will help.

[booof]

hey guys iv got a duel fuel tb 42 and when I run the ignitor with the stock coil threw the ballast resistor it runs perfect but my tacho bounces? I put the bosch gt40 coil on and by past the resistor but that just made it miss under load, it just wont run the same with the bosch coil in it , resistor no resistor, new coil or old coil the tacho still bounches with the ignitor ignition on it and also it misses if I really put in under load which the old points never did, Im thinking of going back to the points as it ran fine with them I was just looking for it to run nicer when cold and abit better fuel economy and all that but I feel like it was a waste of time. also which side of the resistor should the + from the ignitor be hooked up to iv been seeing ppl say one side then others say the other side I havnt tried swapping it over yet but could that make a difference ?

thanks guys

[taslucas]

hey guys iv got a duel fuel tb 42 and when I run the ignitor with the stock coil threw the ballast resistor it runs perfect but my tacho bounces? I put the bosch gt40 coil on and by past the resistor but that just made it miss under load, it just wont run the same with the bosch coil in it , resistor no resistor, new coil or old coil the tacho still bounches with the ignitor ignition on it and also it misses if I really put in under load which the old points never did, Im thinking of going back to the points as it ran fine with them I was just looking for it to run nicer when cold and abit better fuel economy and all that but I feel like it was a waste of time. also which side of the resistor should the + from the ignitor be hooked up to iv been seeing ppl say one side then others say the other side I havnt tried swapping it over yet but could that make a difference ?

thanks guys

Gday mate. Could it be that when the tacho bounces the engine is actually missing but doing it slight enough not to notice?
I installed a pertronix ignitor which was faulty out of the box and gave similar problems as you've described. I got swapped and it was fine.
There is a manual and a trouble shooting guide to the pertronix ignitor2 in the manuals section of the forum which may be of some help.