Megajolt Revcounter Problems

[Stu 18]

Hi all,

 

My Megajolt install has been going really well, fired up first time, even the trigger wheel only needed offsetting 1degree to bring up to true..

 

But... Im having the usual problems with the rev counter, so far, ive tried the Megajolt tacho out, the EDIS tacho output, the PIP line, and even splicing the diode pack into the either side of the coil pack earths with no joy.

 

Now, with the diode pack in, i get a flicker on initial start-up then it stops.

 

So.. if i feed the counter off one side of the coil pack, i can get a reading at half value, as you'd expect. So we can rule out any problems the gauge and/or wiring itself.

 

Now the weird bit.. If i feed off one side of the coilpack for the revcounter, and link in the other feed with a diode (im aware that one of the coilpacks will be firing off the other trigger and hence firing twice as often as it should) then the rev counter works, and gives a good reading.

 

Any ideas?

[James_R 3]

Have you tried either grounding or feeding a 12+ feed in to the wiring goign to the tacho (when both outputs on the coil are bridged correctly)??

 

Otherwise why not do the usual moving pin 1 trick and feed it straight off the ecu??

[Stu 18]

The rev counter wiring itself (im fairly sure) is fine James, as we get a half speed signal when using one of the coil pack drivers, so i think we're ok on that front.

 

Not quite sure how you mean with pin1 on the ECU? On the megajolt?

 

Ive tried every output on the setup, with no joy, its such a stupid thing to be hung up on but this is the last thing i need to sort to finish now!

[adsport69 0]

STU - did you get your tacho sorted? I have a 205 mi running r1's and megajolt, Ihad to mod my tacho itself to run from the MJ signal but works spot on now. It is much more satisfying when it all works properly.

[ORB 227 1 Cars]

Ad, as you know, I am ok at doing stuff, but I need to be told how to do it!

 

As you aslo know, I am running the same set up as you, but I have never bothered to sort the Tacho as I am clueless as to where to start!

 

Any chance you can give me a Morons guide?

 

I have searched the forums in the past, but it all confused me!

 

Thanks

[adsport69 0]

ORB - I Found it that little touch which makes it job done.

 

OK I assume you have the megajolt tacho signal pin connected to the 205 gti tacho signal wire I think it is #112?

 

You need to take your tacho completely out of the instrument cluster.

 

Depending on your tacho you need to locate the signal wire, and remove one of the capacitors it'll be orange or white.

 

Solder a jumper wire between the signal wire and the far side of the 2nd capacitor as below.

 

 

If you are still not sure please get in contact with me and I'll do it for you (either exchange - or send me yours), just been made redundo so have plenty of time on my hands, might even get my turbo techincs cars sorted now.

[Stu 18]

Id forgot all about this thread, and the one over on autosport labs to be honest, yeah like Ad says, you need to remove the rev counter from the cluster and remove all the signal filtering gubbins, its essentially two capacitors and two resistors, then bridging out the feed to the chip, and i added one of the old resistors to the supply to act as a 'pull up' to boost the signal.

 

Ill get some pics up, makes it easier to understand, but i'd also consider taking Ad up on his offer to modify yours..