Regeneration parameters if any.

So had an oddity happen the other day. My '12 went into regen on my way to work, I was running late for work so couldn't allow it to complete and it had only been in regeneration for maybe 5 mins before I shut it down.

Anyhow it was a shorter work day for us so got to work about 9AM and went to leave ~1PM. Car immediately went into regeneration as I was tooling through the parking deck and it finished up ~12-15 mins later.

I thought there were certain parameters to be met for an active regen to start, I never thought it would immediately start one on an engine that had ~4 hours to cool down.

Going to say I like the off the line response much more when the regen is in action, feels like sport mode+. Wish it drove like this all the time.

It started to regen before the engine warmed up?

ss_mini14 said:

It started to regen before the engine warmed up?

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Oh yeah - I park on the 6th floor of our parking structure at work and as I was tooling down to 5 the fans went full tilt and when badging out of the garage the car was sitting at the telltale ~1k RPM. Wondering if only sitting 4 hours the residual heat was enough and it had not fully cooled off, I didn't look at the temp gauge so can't really comment if it was full stone cold.

It has started regens before fully warmed up previously as well. My commute to work is only ~15 mins in the morning and it has started a regen before the coolant temp gauge is in the normal middle, but it has never done it right after start.

03GolfTDI said:

I thought there were certain parameters to be met for an active regen to start, I never thought it would immediately start one on an engine that had ~4 hours to cool down.

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My 2013 Golf did this a couple times recently as well. If you are monitoring the regens are you also monitoring coolant temps?

My car had been sitting for quite a long time as well, and the regen began very shortly after driving it again. I noticed that it REstarted right around the same time the coolant temp hit 140F.

I had a TDI New Beetle a few years ago and it had a warning light to indicate that the engine was still "cold"....I forget the wording in the manual, but it was something to the effect of do not "rev" the engine until the warning light went out, and that light went out right around 135F. So...point is, that VW considered the engine to be "warmed up" at 135F, and maybe that is the case with these cars as well?...

I know in my case the regen didn't start immediately after the starting the engine, but it did begin within only a minute or two and when it did I looked down and noticed that the coolant temp was 140F.

I’ve seen the same thing. Needle starts to move at 50C and at 60 C/140F a regen will start.

Sounds like it may be normal then - wasn't really watching the temp needle, just knew the regen was going because the cooling fans go full tilt and are very audible driving through the mostly enclosed parking structure at my work.

The 4 hour sit after a 20 minute drive to work must have not been long enough to get the cooling temps too low and I guess shutting down in the middle of a regen probably helped keep the coolant temps up.

On the bright side I now don't feel so bad interrupting a regen since it pretty much started back up and was able to finish up the very next drive.

So interestingly enough my car decided to regen again probably 100 miles after previously - I don't think its a fan of my short tripping it so much. It finally completed the regen after 3 largely independent trips.

Day 1 - Drive home and regen starts shortly before getting home. Did not feel like sitting and waiting for the regen to complete so just shut down and left car overnight.

Day 2 - Regen starts on the way to work, stop at a gas station for cigs and shut down with the after run fans still powered on. Regen starts back up immediately once I head the last mile to work but still did not have time to wait for it to finish up so I shut down once again with the after run fans going. It had gotten hot enough to smell the random burning smells emanating from the car. This always concerns me as it would be my luck the car would catch on fire (I don't even let my clothes dryer run if I am not at home) - had a bout of random bad luck recently so I am being extra cautious as of late.

Day 2.5 - Car sat in the parking deck at work for a solid 9 hours so had to have cooled completely off. I park on the 6th level so it takes me a good 3-5 minutes to circle around and down to the exit, low and behold 2 levels down the fans crank up to max speed and regen starts again. Engine coolant temp was still at its lowest limit - guessing it must have hit 140. Fortunately this time I knew what was up so took a longer route home and the car finished its thing.

I have found that short trips significantly shorten the periods between regens. I think it may have been 110-120 miles since the last regen that this one started - they really are quite frequent with my terrible commute.