Having crank signal problems with Symtech MS Controller

[scorplon2004]

First off thank you to 740 Turbo Brick for trying to help me with this issue!

I am trying to run a Symtech configured MS unit which I bought back in February. I am going to use it as a stand alone unit. I have the Innovate LC-1 which according to the install instructions along with the LED, it's working properly. The car is not firing at all. I pulled a spark plug and grounded it and turned it over and there is no spark. I didn't check to see if the injectors are doing anything yet. I loaded all the engine constants and followed the instructions on Megamanual. Its a little hard because they are using MT and not TS. When they got to part about filing in the maps I loaded the Symtech starter map. My theory was if it would start I would know everything is working right and then I could start tuning it. It would not start with the Symtech msq so I tried another on off their site that was closer to what I actually have done to the car. Still nothing.

I noticed that my tach in tunerstudio did not move at all when cranking. The Water temp, air temp, and map are all reading what they should be.

I tried turning the car over while probing the crank signal circuit and I had very low reading that was barely changing .28v to .02v. I put the stock computer back in and checked the voltage and got 1.3v to 4v.

I figured that my crank sensor was not getting proper power supply. I was using a adjustable voltage regulator which I adjusted to 9 volts because the stock computer was outputting that much to the sensors. I figured the voltage regulator didn't have a stable voltage. So I tried splitting the +5v TPS to the crank power circuit. Still the same results. So I bought an external voltage regulator that takes 10 to 16 voltages and outputs 9 volts all the time (Pictured below)

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Now I knew for sure that I had a stable 9volt circuit. Still the same results on the signal circuit. I tried hooking the stock computer back up and used the new voltage regulator to power the circuit and disabled the power circuit coming from the stock computer. The car fired right up.

I checked the crank sensor with the Chrysler DRBIII and found it to be in sync with the cam sensor. So to me the crank sensor is good. But it was suggested that maybe I should replace my crank sensor. So I did and found that I had the same results.

Things I have done...
I checked and double checked every circuit from the 37pin connector to its other end at their respective connectors. All of which are .03ohms. I also check my grounds for high resistance and found all at .03ohms or less. I checked both the 5v and 8v circuits to make sure they were getting the proper voltage and they are.

I don't have an oscilloscope so I can't do any testing with that, which Symtech told me they needed in order to properly diagnose.

This is my most recent picture of the wiring diagram I made while installing the MS. The only difference being I am not splitting the +5v anymore which is what this picture shows.

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Here are links to my Tunerstudio Project, data logs, My pinout from Symtech, and other documents I have stored that may be helpful:

Tunerstudio Project:
Scorplon2004 TS Project.zip

Data logs:
Data logs

Other Documents:
Other Documents

Symtech Pin Out:
Michael_Knight_MS_Pinout.pdf

Basically this is my last effort to make it work before I send it back to Symtech for testing so any help would be appreciated! I know this is long and I may have left information out so bare with me if I say "oh ya i did that already!"

 

[96TurboGS]

That should be right about what you should see while the crank is spinning. (with an average volt meter) Are you sure there are no parts of the shielding wire touching the coaxial cable over the insulator by any chance? It will still show the same resistance even if the shielding wire is touching it at one end. You could try probing the coaxial cable then probing ground for continuity, if you have ~1-3 ohms then there is your problem. You could try feeding MS 3-5 volts with a fixed regulator and see if megasquirt pulls it to ground/low, if it does then your problem is with the wiring. You should be able to see a oscillating crank voltage even without the signal being hooked up to the computer, but the same can't be said for the cam shaft sensor if you unhooked it. You may also want to double check the harness and make sure no bare wires are touching.

 

[scorplon2004]

I'll check again today to make sure the shielding is touching. Just to be clear did you mean that the .02v - .28v is what I should be seeing? Because that is what I'm seeing while cranking. Or did you mean what I was seeing when I had the stock computer hooked up which was 1.3v - 4v was the correct voltages? I will also check the wires for any type of shorts again. It can't hurt to check double and check again!

 

[96TurboGS]

My bad on not being clear. I meant 1-4v RMS is what you should be seeing from the crank signal when the crank is spinning at low RPM's. You see these voltages because the voltmeter is averaging the missing tooth pulses (5v) with the low metal signal (.4v), as rpm increases you start to see somewhere between 2-3v as there are more pulses per rev.

.2v-.6v RMS is what you normally see from the camshaft sensor. In other words you have the right voltages it's just a matter of getting it to work with MS. Make sure MS or your wiring configuration/MS isn't pulling it to ground or adding any resistance.

 

[scorplon2004]

Ok I checked the wiring and the shielding and all is good. No shorts or bare wires rubbing any where! I checked the voltages of the crank signal again when turning it over, with out the MS plugged in and with out the stock computer plugged in and I found the same result of .02v - .28v. So the MS isn't pulling it to ground because it's not plugged in or at least it's not at fault for the small voltages.

 

[#40Fan]

If you could try this just to make sure that TS is working right and so is your MS.

Hook the original computer back up while keeping your MS crank wire hooked up. See if you get a reading in TS.

 

[scorplon2004]

I know its been a long time but I finally had a chance to get to the car and disconnect every wire from the MS except the crank signal wire. I left all the grounds grounded and the power hooked up. I left the stock computer hooked up and the MS unhooked and cranked it over and it fired right up. I turned it all off and hooked the MS connector to the unit, turned the car on without starting it, connected to the MS with tunerstudio, and then tried to crank it over. I got no response. Still cranking over but no tach movement on Tunerstudio or on my tachometer or on the DRBIII scan tool.

Is this a good enough reason to send the unit back to Symtech?