Tunerstudio Composite Logger- Red Trace
 

Hey guys. Having some trouble with a no start on turboed 96 with a MSII and VVTuner. An 01 VVT motor was swapped in hence the VVTuner. I was able to diagnose that the no start was likely due to a missing crank signal trace in the diagnostics logger. Ive attached a picture of the trace I saw. I checked the wiring and have power and ground to both the cam and crank sensors and verified continuity between the cam and crank sensors and the MS. Since the car ran intermittently before, and would die when it got hot, I determined that the crank sensor must be the culprit and replaced it. Still having the same issue. The red trace at the bottom is showing loss of sync, but I'm not really sure what to do with that information. Is it possible that the crank sensor is present in the red trace, but it out of sync with the green cam trace? Any ideas on what could cause this red trace to pop up? Any help is appreciated..I'm really tearing my hair out over this.

with pictures

Quick update..

So I opened up the ECU and checked for continuity from pin 24 (crank sensor input) on the db37 connector soldered on the mainboard to the crank sensor connector inside the engine bay. I have 0 ohms of resistance. Doing some more research and reading a few more threads made me think that the trigger pot (r56) was misadjusted and giving me issues. I zeroed out r56 and r52 by turning both of them 12 turns CCW. I then turned r56 six turns CW and attempted to log the crank and cam signals in the composite logger. I repeated this process six times, turning r56 one full turn CW additional each time until it was maxed out. Still nothing. I checked voltage at r54 (changes depending on what r56 is adjusted to) and noticed that I had just under 2.5V with r56 maxed out on turns. Is this right? I thought it was supposed to be in the neighborhood of 2.5-3v.

the red lines are everywhere it expects a blue line...

ie. your crank sensor is not registering.

Is it possible I got a defective crank sensor out of the box? I shimmed it with a credit card using the proper procedure. Can I just bridge the wires between the cam sensor and the crank sensor plug just to verify that the MS is doing something and responding to sensor input from a known good sensor?

Tried bridging together the crank sensor plug and cam sensor with jumper wires. No response on the composite logger. Any ideas what to check next? I'm going to start looking at the main board to see if I can find any clues.

How thick is a credit card? Might be a little too far away. Regardless I wouldn't suggest bridging pins together to test crank input. You don't typically see bad crank sensors, usually bad cam sensors.

I just used an old discover card I had lying around. Probably just over a mm? Ill see if I can shim it a little closer. I checked the board and there are no obvious burn marks. I have continuity from the crank sensor input pin on the ECU connector to r57 (uninstalled resistor...the pullup was never installed).

I was able to get this resolved. Since the car uses BOTH a VVtuner box and a Megasquirt, I realized that I was losing the crank signal somewhere after the signal went through the VVtuner box. I didn't think to check the wiring going to it since I was getting a cam signal and thought the issue was elsewhere. Fixed the wiring on the VVtuner and now the car starts and runs. Just thought I'd post the solution in case someone else came across the same issue.