Tuning problem.... FT02 spike

[SDDSM]

I'm new to this whole DSM tuning thing. Car is a 1g TSI 5spd AWD. Mostly stock (tubular header, catback exhaust, MBC, datalogger, SAFC, gauges). Here's my question. In looking at my logger, my 02 Fuel Trim has been staying between ~90 and ~110% most of the time. However, when I accelerate to ~4000k RPM's or higher, when I shift, the FT02 spikes and then drops majorly. 160% or more and then straight down to 65% or less.

I'm not understanding exactly why this happens, and how you tune this out. (Or if you need to. Maybe it's normal DSM operation?)

 

[SDDSM]

No one has any ideas?

 

[blcknspo0ln]

First, don't bump your own threads. That's a quick way to piss off moderators and have them close your thread and potentially ban/suspend you.

Second, start your car and sit in it at idle. Monitor your front o2 voltage. It should oscillate anywhere between ~.01V to ~1.1V; like a heart beat. Up and down, up and down. If your front o2 is doing this at idle, it is more than likely in working condition. Do you have fuel mods? or just an SAFC?

 

[SDDSM]

First, don't bump your own threads. That's a quick way to piss off moderators and have them close your thread and potentially ban/suspend you.

Second, start your car and sit in it at idle. Monitor your front o2 voltage. It should oscillate anywhere between ~.01V to ~1.1V; like a heart beat. Up and down, up and down. If your front o2 is doing this at idle, it is more than likely in working condition. Do you have fuel mods? or just an SAFC?

My mistake on thread bumping. I am properly shamed.

Fuel system is stock for now. Just the SAFC and mmcd.


The o2 voltage at idle is spot on. My question/problem is that I have a very large fluctuation in my o2 fuel trim immediately after shifting. Is this a trait of these motors, or is there something I'm missing?

 

[2gGSX]

First, don't bump your own threads. That's a quick way to piss off moderators and have them close your thread and potentially ban/suspend you.

Second, start your car and sit in it at idle. Monitor your front o2 voltage. It should oscillate anywhere between ~.01V to ~1.1V; like a heart beat. Up and down, up and down. If your front o2 is doing this at idle, it is more than likely in working condition. Do you have fuel mods? or just an SAFC?

Technically when an ECG (electro cardiogram) goes up and down like a cycling front O2 sensor, which can also be said to resemble a sine wave, you're about to have a heart attack

My mistake on thread bumping. I am properly shamed.

Fuel system is stock for now. Just the SAFC and mmcd.


The o2 voltage at idle is spot on. My question/problem is that I have a very large fluctuation in my o2 fuel trim immediately after shifting. Is this a trait of these motors, or is there something I'm missing?

Are you looking at STFT fluctuation? This value changes very readily, and the behavior your describing shouldn't make a huge difference. Just pay attention to your LTFT Lo, LTFT Mid, and LTFT Hi instead.

If you're talking about the Front O2 voltage, what you're describing is normal as well.

 

[blcknspo0ln]

That made me laugh.