[Formula jg]

Installed a datalogger (O2, MAP, RPM, etc..) for the bird and having a lot of trouble getting a steady RPM signal. The manufacturer of the device is asking for a wiring diagram I can e-mail them to help me straigthen this out. Are these avaiable on line, I can not find anything.

Please help.

[george kujanski]

I would think the standard tach signal from the HEI distributor is all you need. Shouldn't be any more complicated than that.

George

[Formula jg]

The std. TACH signal from the HEI is creating a very wild and eratic reading on the data logger display.

Do you know where I can retrieve this wiring diagram?

Thanks

[george kujanski]

I would think the mfr. of a automotive logging device would have designed the device to accept a HEI tach signal directly. Perhaps your tach output is faulty, check to make sure the distributor is grounded to the block correctly.

i don't know how the wiring diag will help even if I had it...the tach output comes from the tach term on the distributor. If your car has an dash tach, and you are getting the signal from under the dash, try running a wire from the tach terminal directly from the distributor to the logger in case there's an intermittent condition in the harness or some such thing.

George

[Formula jg]

Dist. is grounded to the eng. block.

I am currently running a signal directly from the dist. TACH to the logger.

Could the signal be disturbed if the TACH wire runs in a plastic conduit that has several other wires running beside it?

[george kujanski]

That might be a possibilty. Depends on the input design of the logger, but the safe thing to do is to separate the tach signal wire from any others. Running that signal parallel to, and in a bunch with other wires may inject noise into the tach sig.

George

[Formula jg]

It's gonna be a pain in the arse but I will separate that TACH wire from the rest because without a good RPM signal this data logger is somewhat of a waste.

Thanks George.

[wh33lman]

Check the basics...Pull the coil cover and be sure the ground "bar" is installed. Then be sure the ground wire for that bar is connected properly, and ohm test the ground.

[Formula jg]

wheelman,

I have an ohm meter but each time I want to test something I never know where to set it at. Can you give me some specifics for testing and setting up the meter.

George,


Here is the data logger mfg.'s respones when I asked how it would help to resolve this problem by providing them with the HEI wiring diagram.

'It would help us to determine where to clip the MSD.
I would like to know how the coil is connected.'

I Google'd it but no luck finding a diagram yet.

Thx guys.

[george kujanski]

'It would help us to determine where to clip the MSD.
I would like to know how the coil is connected."

What about a MSD???? Are you using a MSD box?

George

[Formula jg]

The only MSD thing I have is their GMR pickup wire that was suppose to easily retrieve a good tach signal. Well that was a waste of money.

[george kujanski]

So are you using the GMR pickup or are you using the Tach output from the HEI directly?

George

[Formula jg]

George,

I have tried both the HEI TACH signal connected to the device and then tried the GMR clip connected to the HEI 12V supply. With the GMR the reading was 0 (no RPM signal at all).

What could possible cause these crazy RPM spikes to show up when I'm logging runs?

So how do I ' hm test the ground'?

[george kujanski]

The HEI tach signal should be all the logger needs. Does the logger mfgr state that it'll work with a HEI tach signal? It's a 0 to 12v, Squarish, variable duty cycle signal.

If it is supposed to, I'd say there's a poor connection to the data logger, or you're getting noise into the signal.

George

[Formula jg]

What a coincidence, earlier this morning I e-mailed Zeitironix to enquire if their device is designed/engineered to be used with an HEI. No response yet.

As far as the connection is concerned, I spent quite a bit of time checking, rechecking, grounding, regrounding etc... I even ran a separate, individual wire directly from the HEI TACH side to the RPM signal input of this device, made no difference.

The lack of correct RPM in my logs makes it very, very difficult to decipher the data (even with the MAP connected). I just finished making a bracket and wiring for TPS, this will hopefully help make some sense out of these data logs.

Apprecitate your help George.

PS: I forgot to mention that the mfg. would like to know "how the coil is wired" is their a diagram or can you describe it with words?

[george kujanski]

According to their instructions, the RPM input to their device could is a typical tach input from an ignition coil.

I suggest: remove the HEI cap and make sure there are no broken connections between the actual spade connector and the internal coil connections.

Make sure you have a good connection to the spade TACH terminal.

If you have a spare tach of some kind, try using that to see if you have tach function.

That's about all I can think of....should be straightforward....if the tach works when connected to the tach terminal but not when connected to the logger, I'd say it's the logger problem.

Do you know anyone with a oscilloscope to actually look at the tach signal waveform?

George

[johnta1]

Are you needing the schematic for the HEI module or the car wiring?

HEI module:

[Formula jg]

I don't think I need to do the spare tach test as the dash tach is connected to the HEI TACH terminal and the dash tach is working fine, never had a problem with it.

I will check inside the cap but at this point its a good bet that all internal connections are good.

Unfortunately I don't know anyone with a oscilloscope.

[Formula jg]

johnta1,

Thanks man, I think this is what they are asking for. Gonna forward this link to them now.

Thanks again.

[Formula jg]

OK, here is their response to the diagram. Can someone reword it in simple man terminology?

Zeittronix wrote:

"The diagram helps a lot.
Can you ground the Zt-2 black wire at the same ground as the transistor
ground?
Can you access the wire which goes to the base of the transistor? The one
with the square wave on it? If so connect the Zt-2 green wire into that
signal."