MSefi.com read only forum (Jan.15,2018)

Hi,

I have a BMW 318i (4cyl), and I use EDIS to control the spark and MegaSquirt-II EMS System - SMD PCB3.57 to tune it. I was postponing wiring my tachometer for awhile. When I started, neither of two ways described in the manuals are working.

First way was to run the IDM output (pin 2 on the EDIS module) to the tach input.
Result was: the tach would jump for a second when cranking the car and would stay at zero the rest of the time.

Second way:

Result was: The tach would operate as it should at idle, but whenever I accelerate, my rpm will go up, tach will drop to zero and stay there.

Did I do something wrong or does my tach need something else?

Thanks

I would think you should only need to connect one coil to the tach.

Interesting, would pin 2 be an output of one coil already, the first way I described in my post?

Anyone?

Did you try running the PIP signal also to the tach? My Jag is happy with that...

Elsewhere I saw a 1KOhm resistor being added to the tach gauge input going either to 12V or ground (cant remember which) but I would try ground first.

R12 needs to be at least 3300Ohm otherwise the pip signal is pulled down. (does not reach full 12V peak to peak).

Philip Lochner wrote:Did you try running the PIP signal also to the tach? My Jag is happy with that...

Elsewhere I saw a 1KOhm resistor being added to the tach gauge input going either to 12V or ground (cant remember which) but I would try ground first.

R12 needs to be at least 3300Ohm otherwise the pip signal is pulled down. (does not reach full 12V peak to peak).

I tried to resistor and it did not help. No change except rpm start to read lower.