So with the inferred cam sensor the car uses KV load to determine when to sequence the injectors. So the p0300 and the P0340 are related because the pcm cannot determine where #1 is and cannot sequence the injectors. This also happens on the L series four cylinder cars when a coil fails. The ICM cannot fire one of the coils or it jumps to ground and all the math goes out the window. This is why I stock a known good ICM/coil pack for my car. They have been enough problems over the years, so this makes sense for me. I sent a coil pack to Bones a few years ago when he had this failure. When you loose a coil on my car car you only loose one cylinder, when you loose a coil pack on your car you loose a pair of cylinders. Back when I had my retail repair shop I kept used GM coil packs with the ICM for several different versions as test units. They failed that often. If a plug wire failed, the coil would seek ground directly through the ICM module mounted below the coil pack.

 

Thank you Andy.
I always thought that the CKP on the S cars was what told the PCM where the crank was in its rotation, which in turn allowed the ignition system to determine when to fire spark. Therefore when the CKP failed, spark was killed and injectors were killed to inhibit combustion events at random times with respect to piston position.

​​​​​​So if the ICM is "damaged" along the way, is it only 1/2 dead on an S car engine if you lose 1 coil pack?

I can't seem to reconcile the fact that the engine kept running after the power drop (spark still present) and fuel injectors (at least some) were still feeding fuel on the final leg of the drive home.

But now apparently no spark, still don't know about injectors/gas getting to cylinders.

He mentioned he did not see spark between the coil towers on either coil pack, so that would lead me to believe he did not just drop one coil pack. But if he had dropped both coil packs while driving home the car would have stalled. It is as if something else finished off the ICM after he arrived home. That is entirely possible and I agree swapping in a used ICM is a quick way to test. I always defer to your experience.
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As for compatibility, the ICM from 96 to 2002 is the same, which makes sense because of 96 was the first year for OBD2. Coil packs are identical through that range as well. Price for the OBD 2 version of the ICM is half that of the ICM for my 95. Source: RockAuto.

 

The crank sensor can only determine tdc not where #1 is. The car needs some sort of cam sensor to determine that. Cars without sequential injection don’t care, they just batch the fuel and spark. A distributor in the older designed engines act as cam sensors like the Jeep 4.0 and many v-8 engines. The S car could drive home on two cylinders but never restart cold. I would try a used unit first from a wrecking yard.

 

Thank you, Andy.
Those of us with less experience appreciate the detail into which you are willing to go to help us understand what is going on in situations unfamiliar to us.

 

Finally got a chance to get back to the car this morning....damn work thing getting in the way! Cranked car a few times and then pulled plugs....fuel in all 4 cylinders. As I mentioned before, fuel pump was priming and I had fuel pressure at the rail...so now I know it is making it all the way to cylinders. Sounds like I need to chase down an ICM and coil packs and replace them to see if that is the issue???

Thanks to both of you for the education! I am learning a lot even if I do not get my ride back.

 

What is the resistance between the posts on each coil?

Change one thing at a time

 

18,300 Ohms resistance on each coil.

 

Yikes --7 to10 k is the spec. Disconnect them fr the DIS module and recheck -- should make any difference, but......

Also: check pin B of the 5 position terminal on the DIS module -- not sure which end is A.......
That should be ground. if it is not, it is likely the issue,
This section of the DIS gets this ground from a group of pins in the underhood junction box (UHLB) that appear to be run to the same physical ground???? (I think it is more a of a ground distribution at the fuse panel)

Interestingly enough, the other items getting ground from this distribution include

a PCM and O2 sensor ground
Heated O2 sensor ground
Park Neutral switch

It LOOKS like the PCM is providing ground for this circuit via an internal ground at PCM terminal J4A10 (auto trans)/ J2B06 (m/t) Black w white stripe to E6 on a Brown 68 way connector (A/T) / E8 (M/T) in the UHJB (fuse panel positions I believe
E7 is the PCM + O2S ground
F8 is the Park/Neutral Sw
F6 is the HO2S ground

And F7 is the position that connects to Terminal B on the ICM
All above are BLK/WHT stripe.

This caught my attention only because of your additional O2 Codes that came from nowhere as a part of this.

Terminal A on the ICM should have 12V. independent of whether Pin B is at chassis ground. Can't say much about the others.
Try starting it in Neutral -- Can't believe I didn't think of that. Will rule out switch as cause for issue when it doesn't work.




I would prob pick up new coils at a min --- but first see if the ICM is grounded through terminal B through the path indicated. If not, none of this will function as advertised. I don't like to recommend folks buying parts unless I'm sure it's necessary. those coils are out of spec --you removed the plugwires, yes?

 

I removed the cover from one of those group grounds when I lost grounds to my cooling fans and the horn. There was enough resistance in the lighting circuits to float the ground without causing the lights to quit, however the horn and the cooling fans did not work. I only noticed because the horn quit! It a simple mechanical group of spade type connectors plugged onto a single piece of steel. I had some corrosion so unplugging each wire and reconnecting each solved the issue, it has not reoccured. Saturn runs separate power and ground to every component in the car with very small wire. In the past most cars had larger power wires to a group of components and ground to the body at each component.

 

very interesting.

I've never seen S car coils with resistance that high on the secondaries. Neither side is grounded. And for them to be essentially exactly the same is a bit freaky but could be meter related in terms of resolution. Whether the primaries are grounded shouldn't matter for that measurement because there is no current flowing while making it. You are just flat out measuring a coil. Unless they got suddenly overheated and developed cracks, I've never seen one that high. So there are four functional coils in my driveway. I should go check.