Car falls on face right at 6100 rpm

[kinger]

No, none.  I will need to verify if I have my MIL turned in, I should though. It worked the last time I had mis fires. 


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[scuter83]

Can you post a log of the data while running into the "power loss"?

[kinger]

Can you post a log of the data while running into the "power loss"?

Sure see attached I am using HPT

[scuter83]

Do you have a wideband in the data somewhere I can add?

[kinger]

I do but its not working, that is also new, used to work LOL  I need to dig into that before I go do any more testing I do.  I do have the gauge and that works so i can see its about 12.7AFR at WOT when its doing it.  Fuel pressure dips 2 psi give or take.  The needle blips just slightly. 

[Gunnytron]

You haven't got some safety where by it cuts ignition if the WB02 reads to lean/rich? Just wondering seeing as it's broken.

[kinger]

Good question but no safety cuts like that anywhere. 

[MPbdy]

I've seen people have broken spark plugs that can cause weird issues.  Broken like the porcelain is cracked.  That or plug wires arcing - any evidence of arcing to the headers?

[kinger]

I will work on plugs tonight, as you know they stink, especially #8 when I have my ABS installed...

Last question I see in my tune the DTC MIL is on for P0300 (Random misfire) BUT in the misfire tab under all revolution and cylinder mode tables, the micro seconds are set to the max of 32,767 micro seconds of time between events to declare a misfire.  Is that the equivalent of just shutting off the MIL?  You can adjust from 0 to 32,767  I see on a stock ls1 file there is some variation where they are using between 8 and 900 but nothing over 3000 rpm and the high rpm chart is all 32,767 like mine. 

[FC3S Murray]

Yeah those are set to max.....you will not get a misfire reading.


Find a stock tune file and copy & paste the data for 2500 rpm and up for troubleshooting purposes.


Once you find the misfiring cylinder and fix the issue, put the max settings back (if you want to). Lots of tuners max these cells out when all that really needs to be altered are the idle cells for large camshafts.

Make sure in your scanner you add each individual cylinder misfire count channel and data log accordingly.

[MPbdy]

My experience with my 402 I had to turn off misfire detection also I think because of the 4" stroke.  Maybe an LS7 misfire table would be more appropriate?  I was getting false misfires when running down the highway.

[scuter83]

Looking at the data parameters available, I don't see anything that should be pulling torque.

Spark stays constant, throttle is open, MAP stays high.  Fueling I will take your word for it that it is ok.  Nothing is jumping out as to why you feel a loss of power from the controls side of things.

[spacevomit]

I'd probably disassemble the valvetrain to check the springs closely at this point.

[kinger]

Just a update, I had a buddy come look at it with me this weekend and we cannot find any broken springs, we did a simple bar test where we compressed the valves with a pry bar that had vale spring tool at the end of it, just to be able to see them move and if we could hear anything.  Nothing and all seemed to be about the same pressure to close (with my calibrated arm LOL). 

The filter is a disaster I am on cleaning #3 and still haven't got all the gunk out of it.  I don't think it is the problem, but certainly a good thing to do and I will add this to my maintenance plan before storage each year. 

Going to button up and try again this week. 

@FC3S Murray  what is a good micro second number to use?  In the stock ls1 file its also 32K at the high rpm, it appears OEM only care about misfires in lower RPM unless I am missing it.  I may through 50 in there and do a log and see if they are all consistent. 

[FC3S Murray]

@kinger I would just copy the midrange rpm #'s and paste them into the upper rpm ranges.


It will definitely pick up a misfire if there is in fact one present.