2G Data logger (14point7 iDASH)/Tachometer input not working

[iys]

I've read at least 30 threads from this and other sites related to this topic. Most lead nowhere and the remainder that actually have an answer haven't worked for me.

Car is a 98 GSX. I'm using an iDASH unit from 14point7.com. Works great for my WB O2 sensor. Beginning to wire up other data logging sources, engine RPM in particular.

So far I've tried:

• ECU pin 58 - white wire - Ignition/Tach Signal
• Ignition Transistor pin 4 - white wire (same wire as above, opposite end)
• Ignition Coil pin 2 - blue/red - Coil low side
• ECU pin 89 - Crankshaft Position Sensor
• Autometer Tach Adapter - part 9117 - connected per Autometer's instruction for the Eclipse

I also bought a separate tachometer to test the above inputs separately from the iDASH. I bought the Super Pro 1288 just because it was the cheapest one I could get my hands on locally.

As for the Super Pro 1288, none of the above inputs have been able to move the needle at all. Maybe the tach is defective... IDK. I may throw some more money at this problem tomorrow and buy an Autometer tach to match the Autometer 9117. Not sure about that yet though.

Now for the technical stuff...

I've checked ECU pin 58, ECU pin 89, Ignition Transistor pin 4, and Autometer 9117's grey wire with a digital multimeter.

ECU pin 58 and Ignition Transistor pin 4 show ~.5VAC at idle. I didn't bounce of the rev limiter to get the peak voltage but I did see ~3VAC or more while mashing the throttle a few times.

Autometer 9117's grey wire seems to double the voltages seen at ECU pin 58 and Ignition Transistor pin 4.

I'll need to double-check ECU pin 89 tomorrow as no matter the engine RPM, I seemed to just get fluctuations between 4.0-4.1VAC.

That said...

On the iDASH connected to Ignition Transistor pin 4 or Autometer 9117's grey wire, at idle it reads ~3000 RPM and ~6000 RPM at ~1500 RPM as indicated on the stock tachometer. This all appears to be 4 times the actual (stock tachometer) RPM. Now, this is all despite the doubled voltage of signal coming from the Autometer 9117. Both signals read the same RPM, with the signal off of the Autometer 9117 actually seeming to be a bit cleaner than the signal from Ignition Transistor pin 4 (iDASH has a real time graph that spikes occasionally when running off of Transistor pin 4. No spikes when running off of the Autometer 9117).

As far as the iDASH is concerned, I can customize any values hitting the real time gauges or graph. Not sure yet if I can manipulate the values going to the actual data logs though. Point is, I could always adjust the RPM values displayed by dividing by 4 but I don't want to do that yet as I suspect that the signals I'm getting from these wires, aren't "typical".

The iDASH is supposed to work out of the box and so are hardware guages like the Super Pro 1288 but I'm not able to get either to read correctly so I'm wondering if there is something else I need to do get a "typical" signal. I understand that DSMs use wasted spark ignition. I interpret that to mean we should be seeing twice as many ignition events as are actually being used to operate the engine per coil. Given that we have 2 coils x twice the events, having RPM signals 4 times as active as usual seems to make sense.

My questions:

1. Am I interpreting the impact of having a 2 coil, wasted spark ignition system correctly?
2. WTH are other people doing to get aftermarket hardware guages working on a 2G DSM?
3. (Question 2 worded differently) Is there something else I need to do get a "typical" signal?

 

[iys]

So I figured it all out through trial and error.

Answers to my own questions:

1. The iDASH reading the RPMs as 4 times higher than actual is normal. The Super Pro 1288 I had was apparently defective. I got an Equus tach that worked perfectly and was able to run it off of the same wire that was running to my iDASH.
2. For hardware gauges, just make sure you have it properly set to 4 cylinder. If is set to 4 cylinder and it doesn't read, odds are either your wires aren't making good contact or the gauge is simply defective.
3. The white wire running from Ignition Transistor pin 4 to pin 58 on the ECU is the wire you need. Again, they are both the same wire. You DO NOT need the Autometer 9117 tach adapter unless you're not using the stock ignition and the aftermarket ignition you are using, doesn't have tach signal pin (Coil on Plug for example). At that point, use the Autometer (or MSD) tach adapter. I haven't tried the MSD but I looked at the instructions and they are literally the same. I suspect both adapter are actually the same product in different packaging. Either way, the Autometer tach adapter puts out a VERY clean signal!

That said, I have everything wired up and reading good. The iDASH documentation and support leave much to be desired but the product itself is great. You will need to go into the config web page for the iDASH and set the RPM multiplier to .5. That isn't documented anywhere in the iDASH documentation, on the 14point7 website, YouTube videos, forums nor any other forums I could find. There a vague mention of RPM calibration in the manual but it's not clear at all how to do it or where to go to do it.

So for now, I'm running off of pin 58 and have configured iDASH to clean up the tach signal using adjusters on the iDASH circuit board (instructions in the manual) and set the RPM multiplier to .5. I'll use the tach adapter if I switch to COP.