Stumbles During Warmup
01-23-2017, 01:37 PM
#1
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Stumbles During Warmup
I captured a data log of my engine warming up from a cold start. Disregard the first two minutes or so as I had to turn off Over-run Fuel Cut to keep my engine from stalling. I think that is due to a noisy TPS signal.
Starting at 528s I get a stumble where the engine momentarily dies and then comes back to life. This repeats itself 7 more times at 589s, 623s, 628s, 679s, 711s, 959s and 1015s. It sounds like the momentary stumble you sometimes get when you burn changes to the ECU while running. I'm not getting any sync loss errors during this time. It maintains full sync.
It does not appear as though the stumbles correspond to data points on my WUE curve. My CLT was 53F when I started the engine and the stumbles occur at 131.4F, 137.4F, 140.7F, 141.2F, 145.4F, 148.2F, 166.2F, 169.6F.
Any idea what this is? Is it normal? If not, how can I fix it?
https://dl.dropboxusercontent.com/u/...2_13.31.32.msq
https://dl.dropboxusercontent.com/u/....18%20copy.msl
Starting at 528s I get a stumble where the engine momentarily dies and then comes back to life. This repeats itself 7 more times at 589s, 623s, 628s, 679s, 711s, 959s and 1015s. It sounds like the momentary stumble you sometimes get when you burn changes to the ECU while running. I'm not getting any sync loss errors during this time. It maintains full sync.
It does not appear as though the stumbles correspond to data points on my WUE curve. My CLT was 53F when I started the engine and the stumbles occur at 131.4F, 137.4F, 140.7F, 141.2F, 145.4F, 148.2F, 166.2F, 169.6F.
Any idea what this is? Is it normal? If not, how can I fix it?
https://dl.dropboxusercontent.com/u/...2_13.31.32.msq
https://dl.dropboxusercontent.com/u/....18%20copy.msl
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01-23-2017, 03:37 PM
#3
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Next time I will run a composite log during warm up to see if I can find out what's going on.
I can see in my log that when I get the stumble the Lost sync count number goes up by 1, the SecL number continues to count upwards as normal, Status1 drops from 136 to 0 to 8 then back up to 136.
I can see in my log that when I get the stumble the Lost sync count number goes up by 1, the SecL number continues to count upwards as normal, Status1 drops from 136 to 0 to 8 then back up to 136.
Last edited by freedomgli; 01-23-2017 at 03:52 PM.
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01-23-2017, 04:07 PM
#4
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Also I found additional detail on fixing sync loss errors in the Megasquirt3_Setting_Up-1.5 manual. For some reason I'm always focused on the Tuner Studio manual and forget there is a wealth of information in the other manual. Looks like I'll be busy going through the steps. Hopefully it's just a excessively rich mixture causing misfire. My AFRs at idle are in the 12-13 range as I'm still trying to figure out my VE table and I'm at the very beginnings of the process.
- Loose sensor
- Loose cabling
- Sensor wires running close to spark plug wires or coils
- Slop in timing belt
- VR sensor wired backwards
- Fouled plugs causing misfire
- Non-resistor plugs
- Excessively rich mixture causing misfire
- Excessively lean mixture causing misfire
Having ruled out all those possible causes, you should use the tooth and composite loggers to record the incoming crank/cam pattern and look for the problem. You may well want to enable some noise filtering. See the TunerStudio Reference Guide for additional information on the high speed loggers and noise filtering settings.
- Loose cabling
- Sensor wires running close to spark plug wires or coils
- Slop in timing belt
- VR sensor wired backwards
- Fouled plugs causing misfire
- Non-resistor plugs
- Excessively rich mixture causing misfire
- Excessively lean mixture causing misfire
Having ruled out all those possible causes, you should use the tooth and composite loggers to record the incoming crank/cam pattern and look for the problem. You may well want to enable some noise filtering. See the TunerStudio Reference Guide for additional information on the high speed loggers and noise filtering settings.
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