‘97 5.7 Vortec - ̶n̶o̶t̶ your typical crank no start

[Pinger]

Isn't a 97 Vortec's spark initiated by the timing wheel on the nose of the crank? Didn't Ethan have his slip?

 

[Schurkey]

Isn't a 97 Vortec's spark initiated by the timing wheel on the nose of the crank?

Yes. That's why turning the distributor doesn't change the timing, it just advances/retards the signal from the cam sensor.




90-ish psi cranking compression is still pretty piss-poor. Is your gauge accurate? Has it ever been checked? Is this a thread-in or a push-in compression tester? Aside from finding a tool problem, In MY driveway, that thing would get a leakdown test to see where the compression is going.

A timing light on #1 when cranking could verify both ignition timing and cam timing being correct.

I wouldn't walk across the street for most MSD ignition coils, if they were giving them away for free. Chinese garbage, high failure rates. But if you've got enough spark to reliably fire a spark tester calibrated for HEI, spark intensity isn't the issue.

CLEAN OR REPLACE THE PLUGS so they're not fouled. No engine starts when the spark leaks down the porcelain to ground, instead of jumping the gap.

You disconnected the cam sensor, but you have no codes stored? Seems odd. One wonders if you have a failed ECM.

 

[wyn97]

I know this sounds dumb but your exhaust system isn't clogged right? Or at least messed up?

That's a good question. I haven't looked. I suppose the cat could've taken a dump and clogged the exhaust. I'll have to see. Should still start though. I welcome all suggestions at this point, hairbrained or genius, it might make me look at something I'd never think of.

 

[wyn97]

Yes. That's why turning the distributor doesn't change the timing, it just advances/retards the signal from the cam sensor.




90-ish psi cranking compression is still pretty piss-poor. Is your gauge accurate? Has it ever been checked? Is this a thread-in or a push-in compression tester? Aside from finding a tool problem, In MY driveway, that thing would get a leakdown test to see where the compression is going.

A timing light on #1 when cranking could verify both ignition timing and cam timing being correct.

I wouldn't walk across the street for most MSD ignition coils, if they were giving them away for free. Chinese garbage, high failure rates. But if you've got enough spark to reliably fire a spark tester calibrated for HEI, spark intensity isn't the issue.

CLEAN OR REPLACE THE PLUGS so they're not fouled. No engine starts when the spark leaks down the porcelain to ground, instead of jumping the gap.

You disconnected the cam sensor, but you have no codes stored? Seems odd. One wonders if you have a failed ECM.

Yes, I have attempted to start the engine with both the crank sensor unplugged and cam sensor unplugged, not at the same time, expecting to see a code. I have not seen one at any point.

The plugs are clean, not sure about spark health other than it's blue and looks good, that still doesn't explain the appearance of over advanced timing.

If I keep trying to diagnose, a timing light will be on it tonight.

I agree, compression is low. It's bothering me. Not sitting right, at least. The gauge is brand new, so unfortunately I don't have faith in it. It's a parts house one, needed one in a pinch. That's why I haven't been overly fixated on it. Thread in type, since you asked.

Also, it might be as good of time as ever to mention I work at Holley, that's what dictates my parts choices. As for your opinion of MSD, that's not my responsibility so no offence taken. They've proven to me to be as adequate as the parts house stuff at a minimum, but red. And I like red. That's as much as I'll say on that.

A leakdown test will follow the timing light depending on what buddy has one and when I can get it.

I'm new here and you may have already received a response about this, but I had the exact same thing happen on my 99 K1500 truck and a couple of times before on different gm cars. No codes, just sputtered and quit. It had spark but it was sporadic. The ignition module is bad. It's on the passenger side between the throttle body and valve cover. It has a 3 or 4 wire connection and a heat sink. I've owned a few of these trucks and when the thermal transfer paste dries out, it overheats the module cooking it. There used to be a way to bench test them and a few parts stores had testers years ago, but I'll try to attach a pic of the part.

I was under the impression that a faulty ICM would cause NO spark, not intermittent or poorly timed spark. It won't hurt to try I suppose, they aren't too hard to find.

Again, I appreciate all the help fellas.

 

[Erik the Awful]

I was under the impression that a faulty ICM would cause NO spark, not intermittent or poorly timed spark.

My ignition module went out while I was driving down the road. When it first started, it only acted up above half throttle. Within a mile it deteriorated to misfiring with any throttle input, but idled fine.

 

[Schurkey]

The old 4-pin HEI module could still make sparks even if the variable-dwell feature failed.

The computer-controlled-timing-advance modules can have any number of sub-circuits fail--faulty advance, faulty signal pass-through to the ECM, etc.

 

[Fishinfreak96]

kind of off topic but reading the above posts, I wanted to share...I have this other car that I was messing around with. As time went by I would go out and tinker on it. One of those times I loosened the cam gear to pull the timing belt. Well long story short, I forgot that I did that and wanted the car out of the garage. so I put everything back on to get the car started and I would get a start but I had to rev the crap out of it and feather it to stay running. I thought maybe I had bad injectors or bad fuel. Finally I went back to my timing and found the cam gear was loose and sheered off the pin to align the sprocket to the camshaft. I felt like such a dummy... anyways. car runs great NOW ... I agree with the above posts. start with timing and alignment of tdc.

 

[wyn97]

truck runs. it was the brand new distributor cap.

 

[Schurkey]

I've used Accel HEI coil-in-cap distributor caps and rotors. They seemed OK to me. The ones I bought were brown. Not red. I'd prefer black, but nobody at Accel asked my permission before they went rogue. At least--when I bought them years ago--they were advertised as Made in USA.
www.summitracing.com/parts/acc-8122

Accel 8122 ACCEL Distributor Cap and Rotor Kits | Summit Racing

Free Shipping - ACCEL Distributor Cap and Rotor Kits with qualifying orders of $109. Shop Distributor Cap and Rotor Kits at Summit Racing.

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OTOH, the Vortec caps seem to be a known trouble area from any brand, although some are worse than others. The Vortec caps just suck.

 

[wyn97]

This one was a black Accel cap. Looks shiny still. I should be the first one to suspect new parts, but hey sometimes the lesson learns you, not the other way around.

I'd like to thank everyone for your help. Was a weird one for sure, humbling. I'll wear the dunce cap as long as I can drive any day though! Learned a lot from this, can't say it was a total waste of time, just wish I would've done this before calling a favor to get it trailered back to my house from the parking lot lol.