How to set the timing on your 6.9 or 7.3 IDI and how to buy timing equipment.

mrmatthewhenning

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So I have the Sealey ferret adaptor TL95. Works great on my 1989 F350 non turbo. Got a new truck some months back and it has always ran a bit ruff. 1989 F350 with the banks turbo kit on it. Hooked up today and for the life of me I can't get the RPM to go under 9900 RPM on my timing light. In fact it just stays there no matter the RPM. Tested on my other truck works perfect. Tried it on different injectors on that truck but all read the same 9900 RPM. Sanded the injector line good also. Tried it back on the other truck and it works perfect. Im thinking there must be some sort of interference I'm picking up with this truck. Anybody have any thoughts?
 

trancas

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Great writeup and thread!
My first post on Oilburners!
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I put an oscilloscope on the factory Piezo (thing or "adapter" on top of injector) on #1 injector and get a train of pulses.
Negative going, a couple of volts.
Next, I'll procure a "Digital" timing light, remove the clamp/pickup coil and interface it to the #1 Piezo. The brass part of the Piezo is where I see the pulse.
This will take some experimentation. Timing light might need a particular polarity of the pulse, so a transistor might be required to invert it. Probably depends on the brand of light. Also, being a Piezo, the potential for some high voltage spikes exist and to simply directly connect the timing light's circuitry might damage it. I use a common 10x scope probe, so it helps keep me from clobbering the front end of my scope should such spikes exist. Also, I used a cheap $35 scope from Temu (not gonna use my big scope for such foolishness).
Measured circumference of balancer @ 566mm, so that's 1.572... degrees/mm.
8.5° = 13.36mm
9.5° = 14.93mm
For those not using a "digital" timing light, just carefully measure and mark the damper.
Appears to pick up adjacent cylinders along with a ton of noise. This was taken at idle and I didn't do any math or anything but to verify the existence of that pulse.
God bless
 

trancas

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Oh boy! I had my scope probe set to 10x when I thought it was on 1x, so the voltage of the Piezo spike is ~25 volts! Just thought I'd correct that before anyone blew up a timing light's input circuitry.
 

trancas

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Turns out cheap Imposter DSO from Temu was flakey and I can't promise screenshots in my previous post was of any value. I then purchased another from Amazon which was supposed to be the real thing, JYETech. It was worse than the Temu unit! So don't buy either of those. My other scopes, despite being respectable, are analog. I'm looking for a Tektronix DSO and will start over with the discovery process. Bosch Digital timing light requires a positive-going pulse of at least 1.5v (I tried a battery).
It will only flash once unless input capacitance is drained. Putting a 6k ohm resistors across the input does this fine. 7.3 Piezo creates a negative going pulse, otherwise it'd probably trigger the Bosch without any other circuitry or mumbo jumbo. Need to invert pulse, will try simple transistor circuit and post results once I get this to work.
 

trancas

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Another thought is that since pump is on same gear as the factory tach sensor mag pickup, maybe it could be used as a trigger...
 

hacked89

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Turns out cheap Imposter DSO from Temu was flakey and I can't promise screenshots in my previous post was of any value. I then purchased another from Amazon which was supposed to be the real thing, JYETech. It was worse than the Temu unit! So don't buy either of those. My other scopes, despite being respectable, are analog. I'm looking for a Tektronix DSO and will start over with the discovery process. Bosch Digital timing light requires a positive-going pulse of at least 1.5v (I tried a battery).
It will only flash once unless input capacitance is drained. Putting a 6k ohm resistors across the input does this fine. 7.3 Piezo creates a negative going pulse, otherwise it'd probably trigger the Bosch without any other circuitry or mumbo jumbo. Need to invert pulse, will try simple transistor circuit and post results once I get this to work.
I like what you’re doing with the oscilloscope but for timing and accuracy it takes minutes with the DTI. Are you mostly pursuing this out of interest?
 

Rondo

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I also had thought about using the tack sensor as a trigger for timing the engine. Would need to make a short harness to connect to.
 

trancas

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Tach sensor looked like an analog waveform, probably similar to sensor on rear diff or abs or a Hammond B3...

My goal is to have a simple inexpensive way of just clipping to the existing Piezo with the Bosch light. Pulled a small triac off a junk kitchen blender speed control and am going to try it today.
 

Austin86250

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I’m a little confused, am I pointing the light wrong or is something not set up right?
 

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1189-66

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Does anyone have an extra one of these types of tools lying around? I don’t want to have to pay for something we can recycle in the group.
 

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