Engine speed going nuts!!
 

I have a Half bridge 13brew and it has idled fine before today. The problem is that when i am cranking the motor over and when the motor is running the haltech engine speed is showing a diferent RPM then what it actually is. For exapmle when i am cranking the motor over it will show 1500 RPMS some times and then 0 while im still cranking, and it never did this before. Also when the motor is running you can hear it staying steady at 1500 RPMS and the haltech engine speed will show it boucing all around 2500 3000, just randomly. So i rewired the CAS thinking maybe i has a bad connection and it is still doing the same this. This is on a E6k 634. Thanks
Marc

CAS on a 13B-REW?


-Ted

Yes thats what it came with stock...

Um, usually when you say "CAS", it's what the FC3S and Cosmos come with.
The FD3S uses a crank wheel + trigger mechanism that's a bit different.
Does the Mazda FSM call this a "CAS"?


-Ted

The FSM dose call it a Crank Angle Sensor. I check to make sure the CAS is with in the FSM specs and it is. But now as of this morning it will only spark 3 times while trying to crank it then no spark for the rest of the time cranking. What is going on?

your definitely having trigger issues. The haltech engine speed is based upto what signal it receives from the cas or crank trigger whichever your motor has. Check to make sure your not getting any interference from other wires(power wires, coil wires, spark plug wires, alt wires, etc)

Get an oscilloscope and tap into the trigger wires and see if your getting clean signals.
With magnetic triggers you should see a sine wave. Start your car and see what happens to that wave and watch the haltech at the same time and see if you notice anything abnormal. look at the peaks and they should stay about the same
This will tell you whether it's the haltech or your trigger input because it's one of the two.

I would love to do that but i have a few problems i dont have a oscilloscope and im not sure how to read there output. Is there any other way you can well if its the trigger or haltech. This is how i have the CAS wired from the haltech. On the top first CAS sensor is yellow and to its right red. WHich is NE+ (trigger) which is yellow, and NE- which is input a. Than i have Blue which is G-(input b) and green g+ (home) on the last sensor is this wired correctly? Thanks alot
Marc

a scope is a great idea...but not everybody has $1200 laying around :(

we had a similar problem with ryan hampton's fc last weekend...random rpm spikes.

https://www.rx7club.com/showthread.p...7&page=5&pp=15

^page 5 i listed what i did to fix it.
hope it helps a little bit at least :)

Try swapping out your plug wires .

yea... that was on the list.

i talked to haltech directly and they said to try using 1k ohm resistors in the trigger and home wires and play with the gain from there.