3.2L RPM / Tach Signal for Wideband Datalogging

[scarceller]

At the DME you already tried pin 21 that feeds the tach.
But have you also tried pin 1? this is the coil signal that grounds the coil. It's worth trying this pin 1. Some systems may like the pin 1 ground signal better.

[scarceller]

You should ground everything to the DME ground pins or the main ground screw on the motor at the intake runner for cyl #1 where all the DME grounds are located. Do not ground things any other place than either of those 2 spots.

[dersledite]

Originally Posted by cabmando

I'm curious too why you decided to install one. Are you planning a custom tune in the near future?

The previous Owner had a local Porche tuner install a MAF system that ran extremely poor in all conditions except maybe at WOT. When fully warmed-up. After years of frustration trying to diagnos various issues, I ended up reverting everything back to the original AFM setup. The DME had been heavily modified and I had Steve Wong rebuilt the unit and he put together a custom chip for me. When I got the car on the dyno it turned out it was producing poor power due to extremely low AFRs (nothing higher than 10). I bought the 14point7 wideband as a tool to help me adjust the AFRs back to the 13s which Steve's chip is targeted for.

Originally Posted by scarceller

At the DME you already tried pin 21 that feeds the tach.
But have you also tried pin 1? this is the coil signal that grounds the coil. It's worth trying this pin 1. Some systems may like the pin 1 ground signal better.

Yes I had tried pin 1 as well. I ended up trying to take a signal from the coil, injectors and tach signal at the DME as well as the various devices themselves to rule out the harness wiring as a source of the initial problem. As noted earlier, the issue was something to do with the device itself, not the various points where I was trying to take the signal.

Originally Posted by scarceller

You should ground everything to the DME ground pins or the main ground screw on the motor at the intake runner for cyl #1 where all the DME grounds are located. Do not ground things any other place than either of those 2 spots.

Yes - The wideband unit is grounded to the DME at pin 5. 14point7's instructions are very specific about the ground locations to be used. They advise to keep the lambda sensor ground as far from the wideband ground as possible so I used the harness ground on intake runner 1. Not sure if what I did makes much of a difference because the harness grounds to intake manifold at the end of its run anyways.