Mustang Evolution Forum banner

Data logging experts for engine cut-off

881 views 3 replies 3 participants last post by  5LHO 
#1 ·
Any datalogging experts here?

I have had a sneaky problem for the last several months. The *only* consistent variable is the cut out happens on first start of the morning and at low speeds/rpms; usually while braking to a stop, but today I was accelerating out of my neighborhood.
The cut-out is gentle; no vibration or shaking. I can start the car right back up and it's fine for the rest of the day.
It has occurred 5 times over 7 months, so I cannot recreate this on demand. At all.
I managed to capture some data from my SCT X4. The only thing that stands out of the battery voltage is at ~14.2V and falls to ~12.5V. Just before this happens, the car downshifts to 1st gear (it's an automatic). Now, the radio still works when the engine cuts-out and I don't recall an interruption when playing music.
So, can the car electronics still function at 12.5V? Meaning, is the battery voltage a red herring and there is something else that is happening and the battery voltage falls in suit?

I attached my data log. You can see the battery voltage dive just after the downshift to 1st gear (Capture 1). Capture_Zoom shows when I restarted the car.

Battery: Green
Measured AFR Bank1: Purple
Measured AFR Bank2: Crimson
Gear Commanded: Orange
RPM: Blue
Throttle Position Actual: Dark Blue
MPH: Red

The only things I can think of are:
1) Battery voltage
2) Vacuum Leak
3) Starved for fuel
4) All of the above + something in the tune

Any other thoughts?
 

Attachments

See less See more
2
#2 ·
Similar issue on my 14 auto. The idle is ridiculously low for emissions reasons and, especially if you are using the ac by having the climate set to windshield it can stumble or stall out. I added 50 rpm to the drive idle and it never happened again.
 
#4 ·
You don't lose compression due to an exhaust leak...unless that leak is a burned exhaust valve. All you get is more noise and a possible lean condition on the bank with the leak, because the additional oxygen is messing up the o2 sensor readings.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top