Help please V3 crank sensor problems

[jimspeed007]

Hi guys I have installed the latest Microsquirt controller to a GM C20XE engine that uses a 60-2 crank wheel as standard.
The problem I am having is the RPM signal dropping to 0 around 4000 rpm, it will rev thru it up the road and just gives a stutter but I can't seem to fix it.
so far I have rewired the crank sensor with new shielded cable, replaced sensor, and swapped the wires over to the sensor and changed settings to inverted etc.
I will try and add a log file on here later today
its the latest microsquirt unit from triggerwheels.com and I have uploaded the latest firmware to it (cant remember which no it is but will check the pc asap)
any pointers guys?

[Bernard Fife]

js007,

Unless you post your MSQ and a datalog which can't offer much advice.

Lance.

[Bruce Bowling]

Hi guys I have installed the latest Microsquirt controller to a GM C20XE engine that uses a 60-2 crank wheel as standard.
The problem I am having is the RPM signal dropping to 0 around 4000 rpm, it will rev thru it up the road and just gives a stutter but I can't seem to fix it.
so far I have rewired the crank sensor with new shielded cable, replaced sensor, and swapped the wires over to the sensor and changed settings to inverted etc.
I will try and add a log file on here later today
its the latest microsquirt unit from triggerwheels.com and I have uploaded the latest firmware to it (cant remember which no it is but will check the pc asap)
any pointers guys?

OK, we have seen on some 60-2 tooth wheel setups where there can be an issue at certain RPMs, similar to what you are describing. What appears to be happening is a "resonance" in the sensor.

Try this - take a 4.7K resistor, at least 1/2 watt, and place directly across the VR sensor wires where they go into the Microsquirt. In other words place the resistor on the VR+ and VR- inputs where the VR sensor is going into. By adding this "shunt" resistor you are loading the sensor and changing the resonant behavior.

Try this out and report back here if this helps.

- Bruce

[jimspeed007]

2012-02-26_15.14.01.msl

rpm log

(60.22 KiB) Downloaded 113 times

Ok I found this http://www.useasydocs.com/theory/vr.htm
and carried out the solder bridge which seems to have helped some.
hopefully there should be my logs attached along with the msq setup

[jimspeed007]

mainController.ini

(136.16 KiB) Downloaded 122 times

2012-02-17_19.30.15.msl

(29.26 KiB) Downloaded 121 times

2012-02-17_19.30.15.msl

(29.26 KiB) Downloaded 121 times

oh and the others are here

[jimspeed007]

TPSonly.msq

(27.49 KiB) Downloaded 116 times

I should add that I'm not using a MAP sensor due to large overlap cams and a very odd throttlebody arrangement so its TPS only
4 cylinder wasted spark 2000cc twin cam.
regards Jim

[grippo]

2012-02-26_15.14.01.msl

Ok I found this http://www.useasydocs.com/theory/vr.htm
and carried out the solder bridge which seems to have helped some.
hopefully there should be my logs attached along with the msq setup

If your attached log of 2-26-2012 was made after the solder bridge log, then that fix is useless - it is missing pulses all over the place once it goes over about 3500 rpm (trigger +/- counts down on each one). In that case what you have to do is UNDO the solder bridge mod in the documentation and try what Bruce said. It is important that you only do one of these mods, NEVER both.

Your later log of 2-27-2012 shows a big improvement, but there are still a fair number of missed pulses. So even if this was the log after the solder bridge mod was made, it still isn't good enough, so I would still try Bruce's mod after undoing the solder bridge mod.

[jimspeed007]

Ok thanks so far guys.
None of the logs are after the solder bridge but one is after swapping the wires over on the sensor and changing the ecu settings from rising to dropping (I think!)
I've been up the road in it now and no missfires are apparent but I changed a few bits on the VE table and it wiped out everything when I burnt it for some reason (all the fuel bins said 255 and the ign ones said -0.1) which caused a bit of a problem before I loaded up a saved map again
the plan now is to try and get it close enough with the wideband running the VE table and save that I think.