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Author Topic: Help me understand the effects of Injector deadtimes  (Read 1719 times)
Tb205gti
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« on: June 17, 2024, 09:42:30 AM »

I'm working on a car, that is not Boach based. I have upgraded the injectors from Siemens 330ml to Bosch 380ml.
A tuner have updated the injector scalar and the deadtime maps, but I have _massive_ STFT at idle and part load. at WOT I have expected Lambda. (Using AEM wideband).

Now the reason for me having a tuner to do the file was that it is an ecu with very little public information, and getting the full picture was just too time consuming.
However.. I have been looking at the file, mainly because fuel trims were all over. (We are talking -30%..).

Since WOT fuelling is as expected, then I suppose it is due to a wrongly calibrated TVUB map on it.

So if idle is too rich, ot the point of -30% trims, are the tvub too low or too high? I know voltage is 14-14.4v at idle, so for the sake of simplicity, let's just focus on the value at 14V.

Org is 0.558 ms @ 14v. The tuned file have 0,570 ms @ 14v

The total injection time I log at idle, does that include the deadtime? I log about 2ms at idle, does that mean the effective injection is about 1.5ms (Becuase the deadtime takes 0.5ms). (That would suggest deadtime is too high?)
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Tb205gti
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« Reply #1 on: June 17, 2024, 09:49:35 AM »

I took at look at an S3 file, and took the TVUB from that one - but does the S3 run 3bars fuel pressure or 4 ? if it is 4, then I need to downscale the tvub values accordingly to the 3.5bar my car uses ?
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_nameless
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« Reply #2 on: June 17, 2024, 10:07:25 AM »

I took at look at an S3 file, and took the TVUB from that one - but does the S3 run 3bars fuel pressure or 4 ? if it is 4, then I need to downscale the tvub values accordingly to the 3.5bar my car uses ?
No data logs, no file, not even a listing of what kind of car it is. How do you expect anyone to help you without any information?
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Tb205gti
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« Reply #3 on: June 17, 2024, 10:21:03 AM »

This is more of a conceptual discussion - the ecu I use does not work as Bosch, but it does use the injector deadtimes.
I'm just trying to grasp if waaayyy negative STFT's correlates to too high TVUB, and I then need to lower it in my file.

I'm trying to learn the logic, not to get a file perfected or dialled in - that will come in due time.

So; The data is:

STFT at idle: -30%
Lambda at WOT: as expected and as defined in the file

In other words, mixture is only of at idle - which makes me believe that I need to take a look at the dead times, just need to verify that they need to be lowered.
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Spen Holder
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« Reply #4 on: June 17, 2024, 12:02:30 PM »

Have you looked at ltfs?
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Tb205gti
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« Reply #5 on: June 17, 2024, 01:15:33 PM »

I drive a lot in the city, which means a lot of idling, so LTFT also goes high. Once they go, STFT goes lower (Naturally).
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« Reply #6 on: June 17, 2024, 02:14:40 PM »

odds are krkte is  really wrong too
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Tb205gti
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« Reply #7 on: June 18, 2024, 12:16:07 AM »

odds are krkte is  really wrong too


The ecu does not work like Bosch (It's a siemens EMS2000), so it does not have a KRKTE per se. It has a single bit "injector size factor" and the deadtimes. The car is a Mini Cooper S with upgraded injectors.

I use 380ml injectors - the same car in different trim (JCW) has the same injectors, so I use the single bit from that trim. (As I would expect it to be right..)
Full load is as expected, so not excessive rich here. Higher volumes (injection time) also seems to be ok. It is only when the opening time is short they get excessively rich..
I use the JCW deadtimes, so I'd expect them to be right as well. But it runs massively rich at idle and low load.

IIRC it can be two things:

- TVUB too high for the physical injectors
- Injector(s) have really poor control - which is mostly visible at low opening times

Injectors are brand new and they were flow tested before I fitted them to the car. They flow equally.


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prj
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« Reply #8 on: June 18, 2024, 12:57:27 AM »

You're using old injectors, probably some kind of Siemens ones.
They are super non-linear.

So you have two options.

a) Fit Bosch EV14 and enjoy linear behaviour of injectors where it's enough to set injector constant and deadtime to have perfect fueling all the time.
b) Find the injection correction map(s) in your ECU and tune them in steady state to have the correct non-linear curve for your injectors.
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Tb205gti
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« Reply #9 on: June 18, 2024, 02:49:39 AM »

You're using old injectors, probably some kind of Siemens ones.
They are super non-linear.

So you have two options.

a) Fit Bosch EV14 and enjoy linear behaviour of injectors where it's enough to set injector constant and deadtime to have perfect fueling all the time.

This is what I'm doing (Well, ev6, not 14) - I have bought a set of 0280156063 (Audi S3, 380ml) - they flow roughly the same, have a more modern design and are plug'n'play. Only thing I'm wondering is the spray angle is 10 deg - I need to make sure they spray into the manifold/head - and not directly at the side of it Smiley
If they fail, I'll go for the 0280156102 (Porsche, 440ml).

..But I still want to understand why my current injectors are acting so wierd, and I want to understand the ecu better. Unfortunately those in the know about the ems2K are extremely tight-lipped Smiley


b) Find the injection correction map(s) in your ECU and tune them in steady state to have the correct non-linear curve for your injectors.

To get the idle and part load right (with the TVUB I have now) I need to reduce fuelling by 28% at idle and between 10 % and 25 % for part loads. This gives me okay fuelling with between -3 to 5 % fuel trims.
..But idle sometimes goes super lean (20:1) beacuse the trims do not react quick enough. As the trims slowly rises the afr goes back to normal.
« Last Edit: June 18, 2024, 02:51:51 AM by Tb205gti » Logged
fknbrkn
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« Reply #10 on: June 18, 2024, 09:52:26 AM »

Ive seen many TT225 injectors made from chinesium nowadays

Try to leaking/flow tests them
Also check for TEMIN/TIMIN-like path

tvub:
8 10 12 14 16 v
1,7413   1,1387   0,8107   0,5973   0,4427
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prj
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« Reply #11 on: June 18, 2024, 11:14:54 PM »

This is what I'm doing (Well, ev6, not 14) - I have bought a set of 0280156063 (Audi S3, 380ml) - they flow roughly the same, have a more modern design and are plug'n'play. Only thing I'm wondering is the spray angle is 10 deg - I need to make sure they spray into the manifold/head - and not directly at the side of it Smiley
If they fail, I'll go for the 0280156102 (Porsche, 440ml).

..But I still want to understand why my current injectors are acting so wierd, and I want to understand the ecu better. Unfortunately those in the know about the ems2K are extremely tight-lipped Smiley


To get the idle and part load right (with the TVUB I have now) I need to reduce fuelling by 28% at idle and between 10 % and 25 % for part loads. This gives me okay fuelling with between -3 to 5 % fuel trims.
..But idle sometimes goes super lean (20:1) beacuse the trims do not react quick enough. As the trims slowly rises the afr goes back to normal.

EV6 are also very non-linear.
Are you sure the injectors are genuine though? 25%+ does not sound right.

Also, did you pressure test the whole intake? As in, connect pressure tester to turbo (or charger inlet if supercharged) and pressurize it to see if there are no boost leaks in any of the hoses going to the manifold etc? If you didn't do that before starting tuning then that's the first thing you should do. Otherwise with a leak you're gonna waste a ton of time troubleshooting something that doesn't exist.
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Tb205gti
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« Reply #12 on: June 19, 2024, 03:18:36 AM »

EV6 are also very non-linear.
Are you sure the injectors are genuine though? 25%+ does not sound right.

The ones that in right now are most definetely not genuine.. They are replicas of the original JCW injectors.. And the "quality" shows in the massive corrections needed at short durations. Smiley

The ones I'm putting in are genuine Bosch EV6's, and I'm swapping because the "JCW's" needs massive corrections in the sw. I did flow test them before fitting them, and they had the same flow, so I thought they would be reasonable..

Quote from: prj
Also, did you pressure test the whole intake? As in, connect pressure tester to turbo (or charger inlet if supercharged) and pressurize it to see if there are no boost leaks in any of the hoses going to the manifold etc? If you didn't do that before starting tuning then that's the first thing you should do. Otherwise with a leak you're gonna waste a ton of time troubleshooting something that doesn't exist.

Yes, I did have a leaky bypass valve, but that got sorted by swapping the vacuum from low pressure side to high pressure side (The VGS mod). Other than this I have not identified any leaks.
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Tb205gti
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« Reply #13 on: June 19, 2024, 03:19:31 AM »

Ive seen many TT225 injectors made from chinesium nowadays

Try to leaking/flow tests them
Also check for TEMIN/TIMIN-like path

tvub:
8 10 12 14 16 v
1,7413   1,1387   0,8107   0,5973   0,4427

Thanks! is this for 3bar or 4 bar? My car runs 3.5, so it needs slight adjustment I suppose.
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fknbrkn
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« Reply #14 on: June 19, 2024, 03:54:35 AM »

Thanks! is this for 3bar or 4 bar? My car runs 3.5, so it needs slight adjustment I suppose.

Those for 3 but ive never made a TVUB changes when replacing FPR, i believe it could cost you a few % but not 30 for sure
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