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G4 Xtreme Not firing with hall-effect pick-up

Brad Hansen

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hello, im using a honeywell hall effect sensor (part number:  1gt101dc; data sheet found here:  http://sensing.honeywell.com/index.php?ci_id=50300 ) as a pickup for my 13b in my fd rx7,  the issue im having is that when trying to set base timing im not getting any spark (checking with timing light).  the coils all fire when run in test mode and checked with the light.  the sensor is wired up as follow:

red- 12v IGN

black- ground (white cable in black shielded pair)

white- trig1 (black cable in black shielded pair)

when bench testing the sensor with 12v applied across red and black i get a positive reading from red to white when a ferrous metal is in close proximity to the sensor.  because of this, i set my trigger1 settings as follows:

type- hall/optical; filtering- level2; pullup- off; edge- rising; multi-tooth posn- crank; tooth count- 36; missing teeth- 1.

these settings are different to what i originally had as i was supplied with a dud sensor and the gt101 is just a temporary replacement to see if it would work or not.  we have another fd wit hthe same g4 ecu and the same trigger kit wired exactly the same and it is runnign no issues.  might try to change the sensors over and then try the ecus to see if either helps.

ive attached the map also.

any suggestions?

thanks, Brad.


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Sorry Cameron that was meant to say across red and white; I just went home and messed with settings for trig 1 with pullup off I get no signal when cranking. Turn pullup on and I get signal but no spark.  I did notice that when I turn the pullup on in pclink it activates the fuel pump and I get a trigger signal for about 3-5seconds, is this normal?

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Hi Brad,

With 12V across red and black, you should get a positive reading on the white wire (between white and black) when a ferrous object approaches. If not you need the pullup on, then it should be positive normally and go negative when the object goes close.

When you turn the pullup on, it's detecting a change and assuming it's one tooth going past, so it turns the pump n and registers it as a trigger.


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thanks for all your help today guys; the trigger2 sync setting was what was catching me out by the looks of it.  we ended up getting the base timing set at crank speeds but having issues getting the motor to run on both rotors, was a bit late to keep trying so we'll persist tomorrow.  thanks again for all the speedy replies, i was really coming close to giving up on this, but glad i pushed ahead.


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  • 2 weeks later...

bit of an update on this;

since getting the trigger issue sorted out and finding a dead coil and secondary1 injector wired as primary2, i have finally got the car to start!  problem is it runs like a bag of dicks because the link keeps seeing trigger errors giving it false rpm readings. one error said rpm was 32700rpm!  i found an issue with my loom where a ground got pulled out of a connector and i have since repaired that but the trigger error issue still remains;  i will attach some log files (and my layout file just to make things a bit easier) for you guys to have a look at?  i have another sensor on its way- not a gt101, but the original sensor from the company that made the trigger kit.

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Using a 36-1 trigger wheel with a GT101 is often borderline unless your wheel is very large diameter.  The gaps between teeth need to be quite large (~10mm) and the teeth need to be about 5mm long to get a good reliable trigger from that sensor.  Although the Gt101 is still a popular sensor for crank triggers and seems quite dependable, it does have some negitives such as the tooth/gap size required and the response time is a bit slow for high RPM use.

I generally like to lean towards a VR sensor on high tooth count wheels for better accuracy.

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