Crank Sensor Signal dropping out

[zack_280]

I'm having a problem with my crank sensor signal droppingout right at 25xx RPMs. Here is some detail on my setup.

 

· Injectors - LoZ Injectors using peak and hold output from MS

 

· Ignition – Coil Per Plug using IGN-1A 'smart' coils. These coils have a built-in ignitor.

 

· 12V Grounding - I have a 1/0 cable from the battery '-' to the starter/block. I have another 1/0 from the starter/block to steel plate mounted to the firewall. All other ground connections are made at the steel plate. The only exception is the round for the spark plugs which is made up on the cylinder head.

 

· ECU Grounding - All ECU grounds are run back to the relay board ground terminals. This includes all of the sensors and the 5V grounds from the IGN-1A coils.

 

· Wiring - I ran the wires in 2 bundles based on the location of the items being wired. Bundle 1: This bundle goes to the driver side of the engine and contains the Injectors, TPS, IAT, and O2. Bundle 2: This bundle goes to the passenger side of the engine and contains the coils, CHTS(water temp for MSII), and Crank sensor. In addition all of the wiring is run through the same hole in the firewall, but the body harness, fuel pump, and fan are separated from MS.

 

· Spark Plug Wires - Magnecor. The wires are about 10" long. I mounted the coils on the valve cover on the passenger side of the motor. The coil wiring does get pretty close to the plug wires, but the plug wires are not looped over the harness.

 

I have checked all of the ground wiring and everything seems to be solid and is wired as described above. Other than the ecu killing the revs at 2500 RPM, the car starts and runs pretty good.

 

Here is a link to the IGN-1A coils.

http://www.diyautotu...coil-p-394.html

 

Here is a screen shot of my datalog. Notice how all of the signals are relatively constant except for the RPM signal.

 

Any guidance would be much appreciated.

 

[zack_280]

A few more things. I am still having the same issue with the alternator/water pump belt off and the crank signal wires routed away from all other wiring. So that rules out the alternator as a source of noise.

Edited October 4, 2011 by zack_280

[zack_280]

I added a 10k resistor in series with the VR input. As somewhat recommended in the link below (very useful if you are getting lost sync or have noise issues). The rev seemed a little lumpy, but I didn't really have time to work it out and the car was only running for about 5 seconds. I've got a bit more to do on the car tonight. Hopefully this will get it, but I'll post up if I have to make any changes once I actually have time to test it a bit.

http://www.bgsoflex.com/megameet2008/megameet2008_gnding.pdf

 

 

Here a few keywords in case someone else is searching. If this thread doesn't help, the PDF should.

Breakup, Break-up, reset.