pistonsuk

Ok, this is the deal. I went to a pick-n-pull junkyard and picked up a knock sensor and knock module from a early 90's Blazer for $10. (Pics and wiring diagram here: http://megasquirt.info/ , scroll down on the left to "knock sensing").

I took this the electronics lab on campus to look at it with an oscilloscope. The module runs on 12V and gnd, the output of the module is 8-10V when there is no knock and drops to 0V (or <1V) when hit with a hammer (knock).

In this form it may be useful to just datalog. This depends on the sample rate of the Haltech. The module output does NOT remain at 0V for long, so the haltech might not capture every signal.

I want build a circuit to be used with the timing trim control (short lead leaving Haltech for use with the trim ****). This circuit would also be more useful to datalog because I would want it to immediatley jump down with the sensor, but then "creep" back up. This would most definitely be captured by the Haltech.

This is where your help comes in: I dont have my car, or Haltech manual here.

I need to know:

1) Does timing get pulled from 0-2.5V or from 2.5-5V?

2) What is max timing that can be pulled on both course and fine? I will probably want to use course.

3) The wire diagram for the trim wire lead. (I believe it is a female 3 teminal, like a MAP sensor). I need to know which is 5V, gnd, and signal.

4) What is a good "creep back up" time? (The time it takes for the circuit to give back the full advance that the engine was running before knocking). I used to have a J&S, it tool maybe 3seconds if I remember right? Does anyone have one of these with a readout? Give me a good time to design to.


Justin

Claudio RX-7

iTrader: (1)

The trim control **** is a 10k pot with 3 pins, like you said 5v signal and gnd. Your circuit, if using that GM deal, would have to recondition the signal the specific range, 0-5v, and resistance, 10k, that the haltech is expecting, so you would need a sort of conversion from that +/-10v and +/-1v to work between 0-5v.

Download the Haltech E6K manual from the haltech website, although it doesnt talk about that, its very informative.

Also, the Ignition trim only goes back and forward by +/-7 degrees, so there is no "coarse" option, my guess is you can work out the voltage to advance/retard ratio, or do an actual test.

Hope this helps.

pistonsuk

Thanks for the info.

Only -7degrees! That sucks, I was hoping to pull more. Again what voltage range corresponds to this? 0-2.5V or 2.5-5V?

Thanks,
Justin

pistonsuk

Does the Ignition Trim Control pull leading and trailing?

Justin

Claudio RX-7

iTrader: (1)

It can be set independantly to pull either leading or trailing, but my guess is that with just retarding lead timing you're ok, since at high engine speeds the split is smaller and smaller, the benefits of the split is at low RPMs, where better torque can be made with it.

pistonsuk

I asked if it would pull both because this would not pose restrictions on what kind of split you could run. The fact that it trims each individually means that you must run more split then max retard to be safe.

Can someone answer this:

What voltage range does 0->-8degrees corresponds to? 0-2.5V or 2.5-5V?

Justin

pistonsuk

1) What voltages are associated with the -8deg trim? 0-2.5V or 2.5-5V?

2) What is the amp draw of the signal wire from the trim ****?

Thanks,
Justin

pistonsuk

Well Haltech apparently doesn't want to respond to my questions, its been over a week. Can anyone find out what these are?

Justin

89t295k

U get it worked out?

Claudio RX-7

iTrader: (1)

Ive given pistonsuk some feedback on the inner workings of the trim control and ignition settings, and how the trim **** works, he's apparently working on it.

yusoslo

you might be interested in my friends contraption. He took a hollow brass pipe (5 inches long and 1 in diameter) and drilled a hole into it. Then he bolted the pipe against the block. He than ran a hose over the pipe and then into the firewall which then T's off into a headphone set.
Its like putting a glass up to the wall to hear someone talking in the next room.
We can now hear the engine and tune it to listen for any knocking.

cost about 25 bucks and when your done tuning you can take it off.

pistonsuk

I have sketched up about 10 circuit configurations. I keep finding out more and more about how all of these components work as I read/test more. I have one that I will build and test next week on the breadboard (the electronics lab is closed until next week, we are on spring break right now).

If any of you know of someone in the northern Utah area with an E6K on a running car that would be willing to work with me for testing purposes have them PM me. I have a trim module at home that I could have shipped out. I have a multimeter and enough tools here to finish this project. I just need time and a running car will help too.

Justin

pistonsuk

Well I have a circuit that steady states at 2.5V. It is also adjustable in order to satisfy what ever each haltech wants (i.e. 2.45, 2.55V) for 0degrees advance. The circuit can currently be tripped by any positive voltage from 5-12V. Upon momentary contact with this signal the output immediatly drops to 0.2V (Claudio if you get a chance see what timing pull this equates to, I assume at least 6-7 degrees if not the full 8). The signal stays here for about 1 second and then creeps back to the steady state voltage (~2.5V) in about 4 more seconds. It also resets to the 0.2V output at any time in the rebuild cycle that the circuit is tripped again.

I must now work in inverting the 10 to 0V signal output of the GM module to a 0 to(5-12V) signal to trip the circuit. Hopefully I will find some more time this week to work on it.

Any Haltechs in the Northern Utah/Southern Idaho area?

Justin