[george kujanski]

1. You can connect the ZT-2 black wire to the transistor ground; that would probably be the HEI module mounting screw.

2. You cannot get to the transistor base because it's internal to the HEI module.

I'm actually shocked that they would even ask that question... to me it shows the respondent has no clue about a HEI ignition system, yet this company makes equipment that connects to an automobile ignition system that's been around since 1976??????

I figured a providing a HEI diagram would not help but it does show a lack of understanding on their part.

Anyway, back to the issue...Formula, I don't know what to say. Since connecting it to the HEI TACH, or the GMR gizmo both don't work, I'd say the prob is with the tach input to the logger. Try the grounding thing with the balck wire as suggested by them...since the HEI module ground is the mounting screw, connecting their black wire to the distributor body may help.

George

[Formula jg]

It is diappointing that they are not familiar with such an old and still widely available and used system, but that's what I have so I really need to make this work.

It won't be for a couple of days before a get it, let you know how it turns out if interested.


Again thank you very much all.

[johnta1]

The module is 'supposedly' not very good at higher rpm's.
Maybe convert it by using a MSD 7AL and taking the module out all together.
Use the RPM input on the MSD.
The wire you bought from MSD may be the wire you need for it.

Basically, you're using the MSD as the module.

[Formula jg]

Using a 990 module, rumored to be a decent module for HEI.

On another note,

Got a TPS rigged up but not sure which wires on the sensor pigtail are for gnd, power supply and signal output. Have a multimeter but not very familiar with the settings on it.

Can someone explain what I need to do.

Appreciate it.

[george kujanski]

Where is the TPS from? What are the wire colors if any?

A TPS usually has a +5 volt feed from the ECM, a ground, and a signal wire. Red and black colors would be for pos and ground respectively and the remaining one would be signal.

George

[Formula jg]

George,

The TPS is new, STANDARD part # TH 39 same as GM 17111787. It has 3 wires, grey, blk and blue.

With the blk to ground, blue to 12V and grey to data logger I get a % reading on the data logger that increases very quickly to 100% but the actual throttle is closer to 50% open.

When I switch the grey to 12v and the blue to the data logger device the reading is closer to actual (100% shown on display is approx. 75% actual throttle opening).

Zeitronix tech says:

"The Zt-2 will find the range for 0 -100% to compensate for small TPS
adjustments."

Well I can tell you in my case this quote is not true.

I'm fabricating a small lever that is screwed to the throttle shaft and moves the lever at the rear of the TPS sensor. As I increase the throttle opening the TPS lever needs to slow down enough so the 100% reading on the display is closer to WOT. I'm doing this by grinding a slope into the shaft lever so that the TPS lever slowly falls back when its going through its rotational range of motion.

Yea that was easy to explain.

Anyway, back to the eratic RPM signal. I relocated the data logger ground to the HEI module screw (as suggested by Zeitronix tech). Also ran a ground from the same module screw to the engine block and from there to the firewall. After all that there was ...............NO CHANGE, STILL A BAD SIGNAl!

I failed to mention that the signal clears right up at approx. 2400 rpm. and higher, it was doing this from the begining.

Whats up with that?

Can not acurately deceifer any of the data logged without RPM, very frustrating.

[george kujanski]

If it's like my Cady, gray is +5, blue is signal, and black is the ground return back to the ECM; in your case, the logger ground.



George

[Formula jg]

Thanks again George, looks like I got this wired right.

[Formula jg]

This is Zeitronix lastest response:

Can you show me on the picture of HEI where are you exactly grounding the
Zt-2 black wire and where are you connecting the RPM green wire?
Do you have a potentiometer handy? Something in range of 47K ohm to 100
Kohm, linear (A characteristic) would do. If not do you have a radio shack
near by? They carry pots.
Here, I found one for you:
http://www.radioshack.com/product/in...ductId=2062355

The picture they are referring to is the one in post #17 sent by Johnta1. I'm at work right now and just want to confirm that the HEI TACH connection at the cap is the lead from the module marked "TRIGGER" on the diagram.

[george kujanski]

Yep, should be.

Sounds like what Z is trying to get you to do is install a potentiometer to attenuate the signal goes to their stuff.

The TACH sig from the HEI is essentially a variable duty cycle, 0 to 14 volt signal (plus transient spikes). Running the sig thru a pot will reduce the voltage level but keep the waveshape which their box needs to count RPM. Sounds like their tech thinks the sig has too much voltage and is confusing their input.

Might be worth a try, but I still wonder if it's true, why not just incorporate an attenuator in their box and have the customer run the TACH signal into it directly and have it work? Too much electronic engineering, not enuf automotive know how????

George

[johnta1]

Here's some info that may help.

HEI and MSD

[Formula jg]

John,

Is the TACH wire terminal connected to the 'C' terminal on the module?

[johnta1]

Yes.

[Formula jg]

Copy that, thanks man!

[Formula jg]

Please talk to me like I'm 3 years old because I'm confused about the TPS wiring.

In simple terms here is how I wired it from the sensor pigtail:

1. grey - power source from fuse panel 12V directly to sensor
2. blue - signal out from sensor to data logger input
3. blk - ground sensor to firewall

George you mentioned +5V and now Zeitronix ask if I'm using +5V. I think I'm missing something here because I assumed that meant anything greater than (+)5V thats why I connected to the fuse panel which obviously has the 12v.

How do I get a freak'n 5v source to the sensor?

BTW, here is a quote from them:

'The Zt-2 has a sophisticated RPM noise reduction circuit. For thousands
units sold we had only couple cases where the RPM signal from the
ignition'

Whether that means their system incorpates a attenuator I don't know.

[george kujanski]

In a system with a ECM that the sensor would normally connect to, the ECM internally provides 5 volts, not 12. Most electronics works with 5 volts, sometimes even less.

IF your logger does not directly connect all 3 wires of the sensor, (providing the 5 volt supply) you must somehow create a 5 volt supply for the sensor. Not hard to do, but it requires a few parts from radio shack. BTW you may have damaged the sensor by applying 12 volts to it. Those are indednde to be operated from 5 volts

George

[Formula jg]

George how do I check the sensor is still OK?

Will this work to regulate the 5V supply?

http://smartcat.colehersee.com/sc_ap...rint&strKeyVar

[george kujanski]

To check the sensor, I would get a 5 volt supply, connect it to the sensor +5 and ground connections. Connect a voltmeter to the signal wire and ground wire. Rotate the input shaft of the sensor from min to max, the signal output should go from approx zero volts to near 5 volts. It's basically a potentiometer.

The device you show LOOKS like it would work. Who is the mfgr so I could see if there are any more specs for it?

How about getting a battery holder that holds 4 AA size batteries for your test supply? That'll give you 6 volts, and your signal output then should go from zero to about 6 volts.

George

[Formula jg]

George the mfg. is Cole Hersee.

Please let me know if you think it may not work>

Thanks again.

[george kujanski]

I believe that may work. Connect it to the 12v system voltage and ground the case. Connect the output (load) wire to a voltmeter pos and ground, and adjust the knob for 5 v out. Connect the load wire and ground to the sensor +5 and ground and you should be good to go.

Once set, I'd remove the knob to prevent changes in the output voltage.

George