This is the first V3 board that I've used and I'm getting a pretty regular tach spike that's makes tuning impossible. It spikes every few seconds. Anyone else have this problem? I'm using two VB921 IC Drivers to fire the coil packs. The crank signal is still shared with the stock ECU and I've considered powering the sensor with 12V+ and wiring the signal directly into the MS and disconnect the stock ECU.
On a side note, I also had a pretty regular TPS spike and was bliping the Accel Enrichment. Converting to MAPdot fixed this problem.
#2121, "RE: V3 tach spike... any solutions?" In response to Reply # 0
I have never had any issues with any of the MS I built but I also dont have my coils hooked up either. Try connecting the coils to the stock ecu and see if the problem persists. If it still persists then it must be a sensor or wiring issue.
My setup has the MS ecu installed in the Console, Ground goes direct to the battery point where the ground cable connect to the frame. Wiring exits the firewall behind the washer bottle and is routed with the factory wiring.
Using my car as a test subject i have tested roughly 8 v2.2 ECU's and 6 v3.0 ECU's.
Mummolo tried the 12v at the Crank sensor and still had issues.
#2124, "RE: V3 tach spike... any solutions?" In response to Reply # 1
Back in October, the last time my car was running, I was deaing with some nasty tach spikes. I spent some time probing the tach line coming out of the ECU and it was noisy as all heck. When I get my car back together the crank angle sensor will be powered by an 8 volt supply I added to my 3.0 board, and the line to the sensor will be much shorter and sheilded from any ignition noise. I will still have to find a way to send the signal to the ECU without letting it mess with it.
#2139, "RE: V3 tach spike... any solutions?" In response to Reply # 6 Jun-10-06 07:26 AM by dougie2
I just want to update that, on this particular setup, we've successfully used a Crane HI6-DI2 Ignition Box along with the VB921 drivers installed inside the MegaSquirt. Spark is set to "Inverted" mode and the Crane is wired as pictured in the install manual for a Generic Installation.
That fixed the reset issue.
I still have one issue with this install: TACH SPIKES and DROPS.
Is there anything inside the MegaSquirt that can be adjusted? Is there any hardware (resisters, etc.) that I should try, to clean up the signal?
#2141, "RE: V3 tach spike... any solutions?" In response to Reply # 7
You have the option of using the VR input circuit, which is easily adjustable whereas the opto circuit is not. There are two resistors to adjust the zero crossing point and hysteresis. A lot of information regarding how to adjust those resistors can be found on the main MS site.
One interesting thing I noticed with my scope was the noise I was seeing coming from ignition events into the crank angle sensor signal. The other option is to use more sheilding. A line of coax to the crank angle sensor couldn't hurt.
And yeah, those dropouts are extremely annoying, and they didn't start happening to me until after 024s9.
