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More help needed stumble/missing

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Old 07-12-2018, 08:01 PM   #1  
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Default More help needed stumble/missing

In my never ending quest to get my truck running well and start having some fun I think im down to the last issue. The truck misses or stumbles. Its most noticeable at high speeds just cruising around at 60 the truck will start missing its a fairly healthy stumble when it happens. It happens at any speed or gear just cant feel it as much when driving slower. It does it almost every day and several time on my way to work. My tuner's comment on the problem.

It goes rich for a second then lean for a second. Your cylinder airmass even drops out and the timing dips very low just momentairly.

its like for a fraction of a second the injectors are cut off and timing falls.

So its starting to look like it might be an electrical issue. Has anyone had a similar problem? Any ideas on where to start looking? The scan attached is an older one but at about 9 minutes in start watching you will see the rpms jump for a split second. I can provide more scans if needed. Let me know what you think thanks.

This is an SD tune
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Old 07-12-2018, 08:08 PM   #2  
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Files are to big I will do a shorter scan and post it later tonight.
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Old 07-12-2018, 09:10 PM   #3  
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start watching at 5 minutes and 10 seconds it will happen a few times.
Attached Files
File Type: hpl 18-07-12 19-37-22.hpl (1.79 MB, 3 views)
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Old 07-13-2018, 11:52 AM   #4  
I have a gauge for that
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The RPM is the slowest reacting thing, if you want to see what the problem is, look at the cylinder air mass as that is what determines timing and fuel. You will notice it momentary either spikes upward or downward causing the issue.

Did you try what I suggested about the o2 sensors? Just for fun, next time you are driving, in the scanner disable closed loop fueling to see if it still does it.
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Old 07-13-2018, 02:24 PM   #5  
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Downstream sensors should be here today and I'll give it a try.
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Old 07-13-2018, 03:28 PM   #6  
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Still does with downstream sensors connected. Sent you a scan.
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