Weak Spark on Cylinder 4 - S-10 Forum
 
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post #1 of 4 Old 04-08-2017, 07:15 PM Thread Starter
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Weak Spark on Cylinder 4

I have a 1997 S10 with a 2.2 4banger, that i completely rebuilt myself. New main bearings, cam bearings, piston rings, reseated valves, all new gaskets, new coils, plugs and wire, control module, fuel injectors, new air/fuel filters, new fuel pump regulator.. Did a compression test (12 cranks) 149-152 psi through out all cylinders. even switch the ECMout with a different one..

My problem is that Cylinder 4, when i pull the plug off to check the spark, it barely makes it out the boot. and when i disconnect it, theirs no drop in the performance of the engine. 1-3 has a strong spark, and when i pull those off the engine starts to hesitate more.

I switch the ECM with a junkyard one(it fired the car right up but had the same issues) because it threw a ECM replacement code with the ODB scanner

Codes: P0200, P0405

i have no blinking CEL

ive tried tracing the 5v 12V coming from the ECM, when i uplug the EGR connector the 5v and 12v are there, but as soon as i connect it to the EGR it goes away.

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post #2 of 4 Old 04-15-2017, 08:13 AM Thread Starter
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Re: Weak Spark on Cylinder 4

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Originally Posted by Saintlouis74 View Post
I have a 1997 S10 with a 2.2 4banger, that i completely rebuilt myself. New main bearings, cam bearings, piston rings, reseated valves, all new gaskets, new coils, plugs and wire, control module, fuel injectors, new air/fuel filters, new fuel pump regulator.. Did a compression test (12 cranks) 149-152 psi through out all cylinders. even switch the ECMout with a different one..

My problem is that Cylinder 4, when i pull the plug off to check the spark, it barely makes it out the boot. and when i disconnect it, theirs no drop in the performance of the engine. 1-3 has a strong spark, and when i pull those off the engine starts to hesitate more.

I switch the ECM with a junkyard one(it fired the car right up but had the same issues) because it threw a ECM replacement code with the ODB scanner

Codes: P0200, P0405

i have no blinking CEL

ive tried tracing the 5v 12V coming from the ECM, when i uplug the EGR connector the 5v and 12v are there, but as soon as i connect it to the EGR it goes away.
code: p0200 = was a short in the fuel injector harness (fixed)
code: p0405 = was a bad EGR (replaced)

after getting those 2 things fixed, and reseting the codes in the PCM.. truck is back up and running on all 4.

i also switch out the MAP sensor with a used one from the Junkyard(not sure if that a difference) but between those 3 things my truck is running again
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post #3 of 4 Old 04-20-2017, 11:25 PM
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Re: Weak Spark on Cylinder 4

Glad you got it going.

Quote:
Originally Posted by Saintlouis74 View Post
i have no blinking CEL
I've seen others mention a blinking CEL. What does it mean if it blinks?
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post #4 of 4 Old 04-21-2017, 03:33 AM
It's mostly BS
 
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Re: Weak Spark on Cylinder 4

It means you are probably damaging your emission control system...i.e. your cat.

2001 S10 2.2 5sp ext cab
Don't hit and run...let us know how you fixed it!
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