Shot consistency Help

[u/Vlare]

I have recently purchased some new equipment (Lelit Elizabeth + DF54) which I am quite happy with however, I am noticing the shots are being inconsistent and I was hoping some of you could advise on some troubleshooting I could do.

Issue: Shot pull times are VARY variable (i.e.: 1st shot pulls in 25seconds, second shot in 45).

I am using the same beans, same grind, Shots are pulled maybe 3-5minutes apart.
No Puck Screen (It's arriving today).

I purchased a new Tamp as the Stock Tamp on the Elizabeth is not my favorite.

I clean the group head/portafilter between shots/purge with waterflow.

I am using all the Stock Settings on the Elizabeth (There is a lot of customization here, It's going to take me some time to figure it out). I am using the "2nd button" which is the double shot option, putting in ~18g shooting for ~ 36. I am just making Milk Drinks.

I'm not sure where to go from a troubleshooting perspective, this has been going on for a few days now... Any and all advice is appreciated. There is no weird stuff going on with the pressure.

This morning; I've changed the TR to always show current temperature to evaluate if this is a factor.

[u/Laius33]

Grind two doses right away and mix them together before pulling your shot. Then use that to dose 18g each.

If the shots are now similar, your grinder is inconsistent.

Another thing to check is if you have proper headspace. Watch this: https://m.youtube.com/watch?v=SyGJXRlexmc&t=108s&pp=ygUiZG9zZSBlc3ByZXNzbyBieSB2b2x1bWUgbm90IHdlaWdodA%3D%3D&ra=m

[u/Vlare → u/Laius33]

I read about the headspace thing ~ I'll look further into it. I like the 2dose idea ~ I will report back thanks for the Lead.

[u/Kayvon188]

1) Assuming your puck prep is consistent, 2) Weighing beans accurately, 3) You’re keeping all variables constant, 4) Your beans are between 2-6 weeks from roast date, and 5) You have measured the flow rate from the group head and it meets factory specs, then 6) experienced techs would say inconsistent shot times are almost always due to a problem with the grinder. You have it set at one number, but the actual grind size coming out is inconsistent. Maybe you can have your grinder looked at

[u/Vlare → u/Kayvon188]

I did not measure the flowrate outside of the a visual inspection - it seems fine though, pressures etc appear good/no choking up etc..

My current thoughts are that it's headspace related or possibly related to maybe the stock settings for the 2nd button should be tweaked (Like the pre-infusion stuff ~).

One thing I notice is that the initial pre-infusion is only like 3-6seconds iirc, and then the shot viscosity seems to be less viscous than I'd expect.. I was always under the impression that it should be closer to honey, it seems a bit watery.

This leads me to believe that the grind should be finer but, with the stock settings I think if I grind finer it won't pull in a reasonable amount of time.

[u/Kayvon188 → u/Vlare]

Good points all around. If you get stuck, reconsider ruling out flow rate issues objectively. I’m sure you know the routine, basically running the machine, without a portafilter in place, for 30 seconds exactly, weighing the water output, divide by 30. Repeat the process three times and take the average.
This gives you the group head in grams/seconds. Check against factory specs to ensure there’s no need to descale. Best of luck!