GOLFMK8
GOLFMK7
GOLFMK6
GOLFMKV

AFR swings at steady speed 09G?

StorableComa

Autocross Champion
Location
SoCal, USA
Car(s)
17 GSW S FWD
Attempting to track down what might be a potential issue with my FWD 1.8T with automatic 09G transmission.

Noticed once I installed my JB4 and watching the guages that I'll occasionally have an AFR swing where it will go from 14.5-14.9 swings at steady speed ( so far 35ish to 50 MPH) to jumping up to 15.5-16.0, holding for 3-4 second and then dipping to 13.5 for 3-4 seconds and returning to the 14.5-.9 Which seems to be normal.

Originally saw it on my stage 1 flash, but I've flashed back to stock and still see it, while not as often as with the flash.

Car is currently running stock flash in Map 0. FMIC, catted DP with straight spacer, TIP, intake tube and Afe filter. APR coil and Ruth's gapped to .24 with under 500 miles on them.

Any other 09Gs seen this issue? Attempting to see if its something with the slush box that's normal, or if I have a potential issue somewhere.

Any advice welcome.
 

odessa.filez

Autocross Newbie
Location
Roswell, GA
Car(s)
2016 GSW 1.8tsi auto
Yes. My afr is somewhat erratic with big changes in throttle and lift. Couple years ago ran it by George, was told along the lines of 'logging issue, no worries if trims still behaving'.

There's some discussion in the 1.8 jb4 thread, if you can breeze thru 50 to 70 pages of it :)

I also ocassionally see brief (1-2 cell) spikes in trim in 'real world' logging at autox, usually modulating high rpm...but afr is low
 

Attachments

  • Screenshot_20220514-112934.png
    Screenshot_20220514-112934.png
    156.3 KB · Views: 62

StorableComa

Autocross Champion
Location
SoCal, USA
Car(s)
17 GSW S FWD
Yes. My afr is somewhat erratic with big changes in throttle and lift. Couple years ago ran it by George, was told along the lines of 'logging issue, no worries if trims still behaving'.

There's some discussion in the 1.8 jb4 thread, if you can breeze thru 50 to 70 pages of it :)

I also ocassionally see brief (1-2 cell) spikes in trim in 'real world' logging at autox, usually modulating high rpm...but afr is low
Okay. Thank you!

I didn't know if I had a valve getting sticky or what because my logs look great. George signed off on the last ones I sent him.
It's mainly non cruise control steady MPH cruising city. Light on the pedal and I'll see the AFR swings, but checking my other gauges nothing else is happening to explain them. No misfires, no oil/water temp spike, or fuel issue. Wasn't sure if it's just being to easy on the pedal so it tries to do an injector cut, then kicks back on or what.

I was going nuts because the logs don't show anything obviously wrong.🤣🤣

Good news is I guess I can let IE know they can stop trying to figure it out as it seems to be a quirk of the 09G.🙄
 
Last edited:

odessa.filez

Autocross Newbie
Location
Roswell, GA
Car(s)
2016 GSW 1.8tsi auto

Golfblackedout

New member
Location
Ontario Canada
Car(s)
2016 mk7 golf tsi
Just came across this issue on mine after I tuned to stage 1. This issue is driving me up the wall, I realized that the DV opens which causes the AFR to swing (I think). Has anyone figured out a solution ?
 

StorableComa

Autocross Champion
Location
SoCal, USA
Car(s)
17 GSW S FWD
For me it turned out to be the car running Catalytic tests. I have a DP with straight spacer. Unplugging the rear 02 has stopped it.
 

StorableComa

Autocross Champion
Location
SoCal, USA
Car(s)
17 GSW S FWD
R

Are u tuned? Does your car still run okay?
I am tuned and yes, it runs just fine. Currently running full E85 with MPI. The swings from rich to lean and back again at cruise for me was the ECU running tests, even though I didn't have a CEL it didn't like what it was seeing from the DP and straight spacer.
 

Golfblackedout

New member
Location
Ontario Canada
Car(s)
2016 mk7 golf tsi
Hey guys, I wanted to update you with some stuff I figured out within the last few months with this ‘issue’.

I ended up going to my vw dealer and they told me it’s probably normal and not to worry.

I did end up changing my DV and o2 sensors just in case it wasn’t, but it kept occurring.

Now for my findings.
(For context I live in Ontario Canada and our temps have been warming up lately.) I notice that this issue has been only occurring when temps are 9°C-ish or bellow. This week we’ve had an avg high of +15°and I’ve noticing it stopped happening. When the temps drop at night, it begins to occur again.

So my theory is that this only happens when certain air temps occur and the ecu is able to perform tests on the catalytic converter.
…that or it’s just a very weird occurrence.
 

yakboyslim

Go Kart Champion
It's cat purging and cat stimulation. Cat purging is after fuel cut coasting the ECU runs richer than stoich to purge the excess oxygen in the cat. Cat stimulation is for cat efficiency tests. If you have an OEM cat they are working as intended.

If you don't have an OEM cat, then they probably don't hurt anything. Cat purge can be disabled in a tune (I don't think it often is though) and stimulation seems harder to disable so the only real way to get that to stop is to unplug the second O2 sensor.
 
Top