LMM stand alone loss of power no codes

Mogman

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May 3, 2020
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Papalote, TX
After 750 mi. of relativity trouble free driving I am experiencing a loss of power with no shown codes.

I am pretty sure it is a ECM/TCM issue as I get the power back for another 4-5 miles if I clear all the TDCs even though I do not show any saved or pending codes, I tried to "wait it out" for several miles but I would only get the power back after clearing the TDCs, in fact if I was fast enough when it would start to loose power I would not even have to disengage the cruise control.

All the pressures and temps were fine as far as the instruments were concerned and when running "normally" all seems to be OK

Is it possible I have something "tuned out" that would still affect the ECM and could be cleared at least temporarily?
 

kidturbo

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My fist guess is MAF issues if your running one. I'd say try reinstating all the factory DTC list and see what pops up. Then deactivate again 1 by 1 on things you know are unrelated. Likely not transmission related since it's not limping the TCM. So that leaves just a few things the ECM might not like. Possibly low rail pressure, fuel temp, or even IAT related. The last 2 have tables that pull fueling based on temp, but won't set a code.
 
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Mogman

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OK It looks like fuel related, after shutting down all the shop fans I can hear allot of "gurgling" in the Air Dog, looks like a fuel pickup issue, I did add 10 gal on the way home so it does not look like a fuel level issue, still strange about not getting any codes though...

As far as I can tell with playing around earlier with the Air Dog if it has no fuel to deliver it will still not allow air to be pushed to the engine.
 

Mogman

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My fist guess is MAF issues if your running one. I'd say try reinstating all the factory DTC list and see what pops up. Then deactivate again 1 by 1 on things you know are unrelated. Likely not transmission related since it's not limping the TCM. So that leaves just a few things the ECM might not like. Possibly low rail pressure, fuel temp, or even IAT related. The last 2 have tables that pull fueling based on temp, but won't set a code.
I think you hit it on the head at the end, THANKS!! The MAF and MAP will set a code in my tune
 

kidturbo

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The IAT tables use IAT2 sensor on intake. I set that very conservatively so on my marine stuff it pulls fuel out heavily if air exceeds like 150F.

Plugged a sea strainer couple months ago, lost all power above 2000r. Took me a couple minutes to realize what was wrong cause no MIL. Worked exactly as I set it to...

Sent from my SM-G892A using Tapatalk
 
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2004LB7

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Wasn't there one of those phantom code issues that some experienced when deleting the DPF where it would go into limp mode with no codes? I thought I remember it was a mislabeled code. Maybe something on the alternator code that was miss labeled but when turned off solved the problem?
 
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Mogman

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Well it does not look like fuel delivery, the AirDog is pushing tons of fuel, This is one of the hottest days I have driven so far but I have driven it much harder before, I had slowed to only 60MPH and it was still falling on its face, the engine temp and EGTs were running lower than they normally do at 75mph as would be expected.

I still cannot find the IAT settings in the tune, I need to see what they are so I can tell if I exceed them.

EDIT, it looks like all I can see on live data is IAT1 , at least on the on the 2 readers I am happy driving around with in an unsecured vehicle, I have still not come close to mastering the EFILive, although running a log might be just what I need to do...
 
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Mogman

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Well that did not take too long, pulled out of my driveway and had forgot my phone, before I could do 2 u turns to get back to my driveway it fell on its face.
Now if I can just figure out how to read the log I created.
 
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Mogman

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Well at least I was able to save the file from the hand held, cannot post it as it is not one of the "valid" file types, still trying to figure out how to look at the data.
EDIT, this is what the data looked like while limping back to my gate at 40MPH, certainly does not look like a heat issue as it never got fully warmed up.
LIMPING TO GATE.JPG
 
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JoshH

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MAF reading looks awfully high for the load and RPM I'm seeing in that screen shot. I would look at MAF sensor scaling.
 
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Mogman

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I replaced the MAF and re-seated all the connections I could get to, I started the log at the gate, I only got up to 4-5mph before realizing I was already limping so I pulled over and reset all the DTCs (I have 2 DLC ports so I was running the log on one and had a code reader on the other to do resets) ran fine for 5 miles or so to town, here is a screen shot of nearing the end of that run, ambient temperature was 94-95 deg
65 steady.JPG


After slowing down to go through town I had to do a reset in town as it fell on its face again.
after doing a u-turn and heading back towards the ranch it went a couple miles and fell down again.
This is right after the crash started.
begining of crash.JPG
I should have released the cruise as I let it crash longer than normal before doing a reset and it down shifted and went over 3000 RPM..
Here is the beginning screen, it looks like it has the min-max and average for the entire log.
trip2 static.JPG
Here is the zipped file.
The only thing I saw was at the beginning of the crash the timing changed, I have no idea if that would be normal as the cruise opened the throttle to try to maintain speed or not.
One other interesting thing is after doing a reset the power comes back rather gradually over 5-8 seconds or so not all at one time
 

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Chevy1925

don't know sh!t about IFS
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at what point in the log file you posted does the "limp" happen. looks like at 13:20:20 you try to give her hard throttle and mm3 is limited to 60.

time to start turning codes back on and going from there. Otherwise its all a shot in the dark.
 
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