Tach Signal & Ignition Control

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Six_Shooter
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Re: Tach Signal & Ignition Control

Post by Six_Shooter »

I just looked up the diagrams on the SL1 pertaining to teh engine, most directly the ignition system.

The Saturn uses a very different ignition system than the "GMDIS" that's discussed in the manuals. The GMDIS that's discussed is the 60 degree V6 ignition system most spefically, though there's a 4 cyl variant that's very similar IIRC. In this case however the crank signal is fed to the ICM and then has the same signals between it and the ECM as the dizzy based HEI ignition system, though the EST output is 60* advanced from what a dizzy based system would use. This is why "basic trigger" can be used with that DIS system, and the wastespark part of it is handled by the dual tower coils, not the ECM.

The Saturn DIS feeds the crank trigger directly to the ECU, and then triggers the coils by some other method. I don't have clear descriptions of the wires, but it's possible that these are signals that trigger each coil directly. There are two wires that are just labled as "Ign module" in my diagrams, that could correlate to triggers for each coil. There's also a "cyl 4" wire that I'm note sure what that does, other than maybe there's some engine positional sensing happening and this is a signal for that, sorta like a cam trigger.
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billr
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Re: Tach Signal & Ignition Control

Post by billr »

I think you are mistaken there, at least in regard to the "gen1" (OBD1) S-series Saturns. The CKP sensor does not feed directly to the PCM, that signal goes to the ICM and is "decoded" by the ICM. What kind of pattern is sent on to the PCM, I don't know. That's why I hope the OP can post more detailed info. The "cyl 4" signal is a CMP signal that is generated within the ICM from current/voltage in the 1-4 coil circuitry. My understanding is that the CKP pattern is a standard GM "7X", with the wheel built-in to the crank just to the rear of the center main bearing. Oh, and the earliest S-series ('91-92?) have a different clocking of the wheel than all later years; different by about 10 deg, I think.
Six_Shooter
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Re: Tach Signal & Ignition Control

Post by Six_Shooter »

Definitely not, unless Mitchel is wrong, which is where I looked up this information. I used the info in the OP's first post for year and model...
Attachments
CKPSensorSaturnSSeries.PNG
CKPSensorSaturnSSeries.PNG (111.55 KiB) Viewed 786 times
Tha Toy: 1973 Datsun 240Z Turbocharged, and loads of fun, now MS'd
Tha Otha Toy: 1923 T-bucket Hot Rod, Currently Sniper'd
Tha Daily: 2005 Chevy Blazer
Tha Summer Daily: 1987 Buick Skyhawk hatchback
Tha Long Term Project: 1985 GMC S-10 Jimmy, hasn't been fun for a while
prof315
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Re: Tach Signal & Ignition Control

Post by prof315 »

The Saturn DIS you're looking at ( where the 7X goes directly to ECM and the Ignition module produces the cam signal) is the late model Ecotec engine system, not the old 1.9 Saturn engines. ALL 1.9s use an ICM to condition the 7X as well as fire the coils. The signal that the ICM sends out to the ECM is a basic trigger type square wave.
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billr
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Re: Tach Signal & Ignition Control

Post by billr »

Yep, if that schematic screen-shot posted is what Mitchell's has for the 1.9l S-series Saturn, it is simply way wrong.
alexofnazareth
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Re: Tach Signal & Ignition Control

Post by alexofnazareth »

Hey guys, got sick of trying to deal with the stock system. Switched up to try and use an EDIS-4 system and 36-1 crank wheel.

Here is the trigger wheel and CKPS setup:
ckps.jpg
ckps.jpg (95.18 KiB) Viewed 704 times
I'll need some help determining the Crank Offset to apply to this setup in the Tunerstudio file
Actual TDC lines up with the tooth before the missing tooth [You can see that from the little hatch below the top 8mm bolt]

If I line the missing tooth up at 12 o'clock, that will put the engine at 10* BTDC with 9 teeth until you reach the CKPS.
Will I include an offset of 100* in tunerstudio?
prof315
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Re: Tach Signal & Ignition Control

Post by prof315 »

Are you actually using a full EDIS-4 system with module and everything or simply the 36-1 wheel, sensor and coil pack? EDIS requires a specific#1 tooth angle to work correctly.
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alexofnazareth
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Re: Tach Signal & Ignition Control

Post by alexofnazareth »

Im using the EDIS-4 Module and Neon Coils.

I think I understand that the bypass/failsafe mode may be affected if the CKPS is in the wrong position on the crank wheel, but if the MS3 SAW signal is being read I can just offset the angle in the software. Correct?
billr
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Re: Tach Signal & Ignition Control

Post by billr »

What happened to your plans to gut the Saturn ICM and put BIP373s in there, using the ICM only as a case and mount for the coils?
alexofnazareth
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Re: Tach Signal & Ignition Control

Post by alexofnazareth »

billr wrote:What happened to your plans to gut the Saturn ICM and put BIP373s in there, using the ICM only as a case and mount for the coils?
Got frustrated [as usual] with attempting to use the Saturn gear, and decided just to go with a tried and true system.
Im being sent on assignment to japan in 3 months and want to get this thing running before I go.
EDIS seemed like the simplest route to go.
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