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Misfire or Stumble, Mechanical Testing with Knock Sensor?
- graywave
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Topic Author
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- Adv. Diagnostics New Hampshire
7 years 1 month ago - 7 years 1 month ago #22696
by graywave
Confirm what it's not, and fix what it is!
Misfire or Stumble, Mechanical Testing with Knock Sensor? was created by graywave
Hi Folks,
I recently changed out a pair of knock sensors on a 2004 Chevy 5.3L Engine. After testing the new ones, I noticed an anomaly in the waveform that was repeating and thought of getting a cylinder 1 ignition trigger event to try and get an idea on what cylinder its coming from. It actually lines right up with the cylinder 1 event but starts BEFORE the ignition coil fires so I am not sure what to think of this. Some events happen during other cylinder events.
I think the discussion came up before about using knock sensors to possible diagnose a misfire or a slight stumble thats not getting picked up in misfire data or doesn't really misfire completely. Below is a capture of the knock sensors and cyl 1 ignition coil trigger.
Is there any use in diagnostics for these?
Yellow Trace is the Rear Knock Sensor
Green Trace is the Front Knock Sensor
Blue Trace is Cyl 1 IGN Coil Control
I recently changed out a pair of knock sensors on a 2004 Chevy 5.3L Engine. After testing the new ones, I noticed an anomaly in the waveform that was repeating and thought of getting a cylinder 1 ignition trigger event to try and get an idea on what cylinder its coming from. It actually lines right up with the cylinder 1 event but starts BEFORE the ignition coil fires so I am not sure what to think of this. Some events happen during other cylinder events.
I think the discussion came up before about using knock sensors to possible diagnose a misfire or a slight stumble thats not getting picked up in misfire data or doesn't really misfire completely. Below is a capture of the knock sensors and cyl 1 ignition coil trigger.
Is there any use in diagnostics for these?
Yellow Trace is the Rear Knock Sensor
Green Trace is the Front Knock Sensor
Blue Trace is Cyl 1 IGN Coil Control
Confirm what it's not, and fix what it is!
Last edit: 7 years 1 month ago by graywave.
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- Chad
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- I am not a parts changer.
7 years 1 month ago #22813
by Chad
I couldn't say for certain but, I would guess there is. It sure is intriguing the way it kind of "cradles" the coil control. Are there any know issues with is vehicle? It seems a little more defined on the yellow (rear) trace. What cylinder is on exhaust stroke when #1 is on compression?
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
Replied by Chad on topic Misfire or Stumble, Mechanical Testing with Knock Sensor?
graywave wrote: Is there any use in diagnostics for these?
I couldn't say for certain but, I would guess there is. It sure is intriguing the way it kind of "cradles" the coil control. Are there any know issues with is vehicle? It seems a little more defined on the yellow (rear) trace. What cylinder is on exhaust stroke when #1 is on compression?
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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