VW Megasquirt Forum

Firstly, I'm not sure if this is the right space for this, but here goes...

I'm new to the MS world. I've run an EDIS controlled by a MegaJolt for some time and it has been fantastic and reliable. The trouble I had was I was running a blow through turbo, and Kadrons just don't like pressure, so I decided to go with EFI. As the EFI needed controlling along with the EDIS, I figured the way to go is MegaSquirt controlling both, so that's what I've done.

Anyway, lots of research and back and forth to the MS supplier and I've finally got a set-up that talks to my laptop and starts first time.

I do have a problem though that I'm hoping someone here can provide an answer for. I've searched thesamba and shoptalk and can't seem to find an answer. My tacho needle (the one on the dash and the one in TunerStudio) are jumping about madly and along with it, it seems like the engine missfires and spits and splutters along with it.

When I first installed the MS2, the tacho on the dash wouldn't work, but one guy I spoke to suggested using terminals 85 and 86 of a relay between power and the tach signal wire, and apparently the coil in the relay provides a voltage spike or something (I'm not clued up on what that means, but that's what he said) and it worked! I have tacho operation. But the tacho is jumping wildly now.

I will try and attach a datalog so you can see it. Nope, won't let me attach cos its an extension msl file, sorry.

Has anyone experienced this or have any clues for me to fix it? I'd love a steady tacho needle so the fuel map and ignition map aren't jumping all over the place.

Many thanks, Marc.

I dont know EDIS, but the basics.

Tach is known to work? Have a spare to swap in? Connectors tight?

I saw a post about using the IDM signal for tach, makes it jumpy. Yours have the CTO signal?

Thanks Jim. Checked everything and all was good.

Only seems to jump a bit when it's cold now... go figure! Works great once it's warmed up and running.

Cheers,
Marc.

Ive seen cheapy tachs do that in the past, but if its not too much i wouldnt mess with it.

Yeah I've seen that too, but this isn't a cheapy, it's an Autometer and pretty expensive too. I think it's something in the EDIS or the MS2 because when it jumps, the engine misses, so it's definitely having an effect on the firing. But like you say, it isn't bad, so I'm not going to worry about it at this stage. I've got begger fish to fry - see the post about flat spotting!

Cheers, Marc.