Urgent Motor Help Needed After Tuneup

[Nick88]

Yes, an open circuit (plug wire not attached to a grounded spark plug) can damage the ignition coil. A damaged coil can damage the ignition module.

When the ignition secondary (plug wire) circuit opens, the coil voltage goes sky-high. Very hard on everything, the insulation is stressed.

If you have a misfire, the O2 sensor sends a false-lean signal to the computer, driving it into rich-command. The BL goes up until the Integrator is happy.

So I probably have a misfire on the driver side of the motor affecting the o2? I assume cylinder 5 since that was the problem. So I should definitely replace the coil, should I replace the spark plug wire?? Its brand new so I hope I didnt damage it. Do you think ICM is ok? I'll probably toss in a spare accel coil thats good and see if it runs fine. ICM is relatively new ACDelco and I spent like $25 on some serious heat sink gel from best buy so I hope I didnt blow that yet either.

 

[Schurkey]

Coils and ignition module problems are not cylinder-specific. A cylinder-specific misfire (on cyl. 5) is something else.

 

[Nick88]

Coils and ignition module problems are not cylinder-specific. A cylinder-specific misfire (on cyl. 5) is something else.

I dont know if it was specifically 5 it just sounded like driver side, 5 was the problem when the wire popped off. I swapped in the accel spare coil and thr idle seemed a little smoother but the truck felt more sluggish then with a delphi, so I just went out and popped in a nice brand new ACDelco one to be safe, havent tested it yet though.

 

[Road Trip]

Out of curiosity, would having one spark plug wire off damage the icm or the coil???

Yes, an open circuit (plug wire not attached to a grounded spark plug) can damage the ignition coil. A damaged coil can damage the ignition module.

When the ignition secondary (plug wire) circuit opens, the coil voltage goes sky-high. Very hard on everything, the insulation is stressed.

I agree with Schurkey. Back in the day the pre-HEI ignition systems didn't really put out enough zap
to hurt/wound themselves when driven into an open circuit (aka unplugged spark plug wire) ...but these
new systems can hurt themselves when operated in a illegal configuration.

FWIW here's a short video where the HEI system is only connected into the right bank of a V8.
(It's obvious why once you see the test setup.) Towards the end of the 20-second video, pay
close attention to the firewall side of the dizzy cap, and you will see 2-3 lightning bolts from the
#5 spark plug wire terminal, including one after the engine stops running. Pretty impressive.
(#36 - HEI is the Zeus of ignition systems)

Note: That link dumps you to reply #36. Read also #37 for dizzy & cylinder numbering.

So I probably have a misfire on the driver side of the motor affecting the o2? I assume cylinder 5 since that was the problem.

^^^ That's a good educated guess. I would also be leaning guilty until proven innocent.

So I should definitely replace the coil, should I replace the spark plug wire?? Its brand new so I hope I didnt damage it. Do you think ICM is ok? I'll probably toss in a spare accel coil thats good and see if it runs fine. ICM is relatively new ACDelco and I spent like $25 on some serious heat sink gel from best buy so I hope I didnt blow that yet either.

If it was me, in an abundance of caution I would replace both the coil and the ICM in order to regain control of the situation.

(When the voltages skyrocket, the high voltage in the coil secondary will blow back through any weakness in the coil's insulation
into the low-voltage primary winding, which then couples it directly into the electronics in the ICM, making for wounded bits/flaky
behavior at best, and no worky/crank but no start at worst.

High voltage (in particular 40+KV high voltage + high current) can be unpredictable stuff, as opposed to the surrounding 12v
circuits -- these circuits are much more predictable by comparison. :0)

While you are in the neighborhood, inspect the inside of the cap and the rotor (both sides) to see if there's any visual indication of
tracking and/or burn through. I'm not thinking the spark plug wire will be damaged, but I would still go over it with a fine-tooth comb,
looking for tell-tale discoloration. Here's a picture of arc-through on a spark plug wire:
(2nd photo in this reply shows spark plug wire arc-through discoloration)

When you get the high voltage side all sorted out and the engine running on all 8 cylinders, I highly recommend that you add some
Chevron Techron to the tank (1 oz/gallon), fill it up, and proceed to drive the truck for 1/2 hour or better on the highway.

It should run smoother after the highway run, and by the end of that tank it should be smoother still. Between this and the
water decoking you have already performed, it should be running appreciably better than before.

Best of luck. Let us know what how this all turns out. (For the benefit of others researching the do's & do nots of reviving
carboned up engines.

Cheers --

 

[Nick88]

I agree with Schurkey. Back in the day the pre-HEI ignition systems didn't really put out enough zap
to hurt/wound themselves when driven into an open circuit (aka unplugged spark plug wire) ...but these
new systems can hurt themselves when operated in a illegal configuration.

FWIW here's a short video where the HEI system is only connected into the right bank of a V8.
(It's obvious why once you see the test setup.) Towards the end of the 20-second video, pay
close attention to the firewall side of the dizzy cap, and you will see 2-3 lightning bolts from the
#5 spark plug wire terminal, including one after the engine stops running. Pretty impressive.
(#36 - HEI is the Zeus of ignition systems)

Note: That link dumps you to reply #36. Read also #37 for dizzy & cylinder numbering.




^^^ That's a good educated guess. I would also be leaning guilty until proven innocent.




If it was me, in an abundance of caution I would replace both the coil and the ICM in order to regain control of the situation.

(When the voltages skyrocket, the high voltage in the coil secondary will blow back through any weakness in the coil's insulation
into the low-voltage primary winding, which then couples it directly into the electronics in the ICM, making for wounded bits/flaky
behavior at best, and no worky/crank but no start at worst.

High voltage (in particular 40+KV high voltage + high current) can be unpredictable stuff, as opposed to the surrounding 12v
circuits -- these circuits are much more predictable by comparison. :0)

While you are in the neighborhood, inspect the inside of the cap and the rotor (both sides) to see if there's any visual indication of
tracking and/or burn through. I'm not thinking the spark plug wire will be damaged, but I would still go over it with a fine-tooth comb,
looking for tell-tale discoloration. Here's a picture of arc-through on a spark plug wire:
(2nd photo in this reply shows spark plug wire arc-through discoloration)

When you get the high voltage side all sorted out and the engine running on all 8 cylinders, I highly recommend that you add some
Chevron Techron to the tank (1 oz/gallon), fill it up, and proceed to drive the truck for 1/2 hour or better on the highway.

It should run smoother after the highway run, and by the end of that tank it should be smoother still. Between this and the
water decoking you have already performed, it should be running appreciably better than before.

Best of luck. Let us know what how this all turns out. (For the benefit of others researching the do's & do nots of reviving
carboned up engines.

Cheers --

So this is interesting, put in the new AC Delco coil and felt like it had better power again. But i noticed the truck was starting to get some knock counts at random when I would first start accelerating. Well I get on the parkway for a while and get a SES. I didnt check it but I already knew it was 32- EGR. Even after cleaning manifold and checking everything and sealing exhaudt leaks I still get it. So anyway I drive to get gas later and Im pulling into the station and boom engine just dies. I couldnt hear if it sputtered or anything because of music but after cranking for a sec it started and I pulled it in. Right before it died the SES popped on. This time I checked it and sure enough it was 32 but also 44 which is lean exhaust. I knew exhaust was lean from the scanner but I wonder if truck died from the ICM being slightly damaged from the wire being off. Still idles and drives a tiny bit funny so I need to see. Any opinions before I rip into it?
I dont think I ever had the motor running so lean before the plug wire was off, I wonder though if when I did the intake manifold, i wire wheeled it and caused a slight thermostat gasket leak from the wire wheel. Im wondering if I caused a vacuum leak from wire wheeling around the vacuum fittings. I assume that could make it run lean snd also make it idle funny, but the idle started acting up after the wire was off.

 

[Nick88]

I agree with Schurkey. Back in the day the pre-HEI ignition systems didn't really put out enough zap
to hurt/wound themselves when driven into an open circuit (aka unplugged spark plug wire) ...but these
new systems can hurt themselves when operated in a illegal configuration.

FWIW here's a short video where the HEI system is only connected into the right bank of a V8.
(It's obvious why once you see the test setup.) Towards the end of the 20-second video, pay
close attention to the firewall side of the dizzy cap, and you will see 2-3 lightning bolts from the
#5 spark plug wire terminal, including one after the engine stops running. Pretty impressive.
(#36 - HEI is the Zeus of ignition systems)

Note: That link dumps you to reply #36. Read also #37 for dizzy & cylinder numbering.




^^^ That's a good educated guess. I would also be leaning guilty until proven innocent.




If it was me, in an abundance of caution I would replace both the coil and the ICM in order to regain control of the situation.

(When the voltages skyrocket, the high voltage in the coil secondary will blow back through any weakness in the coil's insulation
into the low-voltage primary winding, which then couples it directly into the electronics in the ICM, making for wounded bits/flaky
behavior at best, and no worky/crank but no start at worst.

High voltage (in particular 40+KV high voltage + high current) can be unpredictable stuff, as opposed to the surrounding 12v
circuits -- these circuits are much more predictable by comparison. :0)

While you are in the neighborhood, inspect the inside of the cap and the rotor (both sides) to see if there's any visual indication of
tracking and/or burn through. I'm not thinking the spark plug wire will be damaged, but I would still go over it with a fine-tooth comb,
looking for tell-tale discoloration. Here's a picture of arc-through on a spark plug wire:
(2nd photo in this reply shows spark plug wire arc-through discoloration)

When you get the high voltage side all sorted out and the engine running on all 8 cylinders, I highly recommend that you add some
Chevron Techron to the tank (1 oz/gallon), fill it up, and proceed to drive the truck for 1/2 hour or better on the highway.

It should run smoother after the highway run, and by the end of that tank it should be smoother still. Between this and the
water decoking you have already performed, it should be running appreciably better than before.

Best of luck. Let us know what how this all turns out. (For the benefit of others researching the do's & do nots of reviving
carboned up engines.

Cheers --

So I tossed in a new Dyna Mod ICM and it seems to be running pretty good at idle now, but the truck is still running very lean, still aorund 140 ish on the tuner. I checked the vacuum fitting I thought was leaking and re sealed it. Any other ideas?

 

[Scooterwrench]

So I tossed in a new Dyna Mod ICM and it seems to be running pretty good at idle now, but the truck is still running very lean, still aorund 140 ish on the tuner. I checked the vacuum fitting I thought was leaking and re sealed it. Any other ideas?

You may have fried the O2 sensor while de-carboning your engine. The thermal shock of cool water on a hot sensor is like throwing a screaming hot ceramic dinner plate into cold water,it will bust to pieces. Also any exhaust leaks upstream of the O2 sensor will cause it to read lean. For the code 32 which is EGR control valve,check the open vacuum port where there is normally a foam filter. That foam deteriorates and either remnants of the foam filter or dirt may have plugged that port.

 

[Schurkey]

the truck is still running very lean, still aorund 140 ish on the tuner.

WHAT is "140"?

140F temperature?
140 fuel trim?
140 knock counts?
.140 O2 voltage?

Something else?

 

[Scooterwrench]

WHAT is "140"?

140F temperature?
140 fuel trim?
140 knock counts?
.140 O2 voltage?

Something else?

Fuel trim,I'm guessing integrator.

 

[Nick88]

You may have fried the O2 sensor while de-carboning your engine. The thermal shock of cool water on a hot sensor is like throwing a screaming hot ceramic dinner plate into cold water,it will bust to pieces. Also any exhaust leaks upstream of the O2 sensor will cause it to read lean. For the code 32 which is EGR control valve,check the open vacuum port where there is normally a foam filter. That foam deteriorates and either remnants of the foam filter or dirt may have plugged that port.

I dont think the water is cool at that point, after passing through the engine the water vapors coming out at the tail pipe are extremely hot.

No exhausts leaks by O2 sensor.

I will check that for code 32, I have tried literally everything. New EGR when i found the old was bad, checked the solenoid, cleaned egr, cleaned the passages in manifold, checked for vac leaks.