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Author Topic: Finding injector parameters with the injectors already on the car  (Read 16400 times)
azxuts
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« Reply #15 on: May 18, 2022, 11:20:58 AM »

Yes it's wrong.

MAF affects load. Having incorrect MAF calibration means that everything in the engine from throttle and knock control to ignition is wrong.
Your approach of garbage in, garbage out makes tuning and getting anything right a nightmare.

This is a perfect example of how not to tune.
Yes, thank you for clarifying what I have said twice now.

In my particular case this is what worked best for me, as I did not have data for my MAF housing or my injectors beyond a rough estimate of what the injectors flowed. Yes, I should have done one at a time, but I still stand by this method of forcing AFRs to confirm where inaccuracies are hiding, particularly since we can't rely entirely on seeing if ps_w==pvdkds_w to verify MAF accuracy at light load, especially when we may also be fighting an unknown TVUB in these light load areas.

Shit, don't take this the wrong way but I could even argue your method in the OP is, the perfect example of how not to tune since you should just have correct injector data from the manufacturer instead of making assumptions, but that would be retarded and completely ignoring the fact that this is tuning and that there will always be areas that need to be tweaked here and there to get things right.
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prj
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« Reply #16 on: May 20, 2022, 08:22:49 AM »

Shit, don't take this the wrong way but I could even argue your method in the OP is, the perfect example of how not to tune since you should just have correct injector data from the manufacturer instead of making assumptions, but that would be retarded and completely ignoring the fact that this is tuning and that there will always be areas that need to be tweaked here and there to get things right.

The only thing that manufacturer data will help you do is set TVUB and KRKTE, it will not help you with fuel system and injector linearity.
Furthermore, using the method in the OP will have the ecu calculate the correct load and correct fueling.

Your method is pure garbage in garbage out. As soon as load is wrong in the ECU, everything else is wrong too.
TVUB, KRKTE, FKKVS - this affects only fueling, nothing else. If you try to randomly adjust KFKHFM for changes in fueling system, load will be wrong everywhere.

In my particular case this is what worked best for me, as I did not have data for my MAF housing or my injectors beyond a rough estimate of what the injectors flowed. Yes, I should have done one at a time, but I still stand by this method of forcing AFRs to confirm where inaccuracies are hiding, particularly since we can't rely entirely on seeing if ps_w==pvdkds_w to verify MAF accuracy at light load, especially when we may also be fighting an unknown TVUB in these light load areas.
This statement shows again that you do not understand load in ME7.
ps_w in a modeled car is based on KFPBRK/KFPBRKNW/KFURL/KFPRG, not just on the MAF. If the MAF you use is not a random sensor in a random tube, but rather a larger OEM unit, then yes, you can enter the characteristic and then use the other maps to get ps_w more or less right at WOT. Furthermore on a car with a MAF ps_w matters very little, it's only used for a few things.

If fitting a random MAF, random injectors then you do not know anything about anything anymore.
People who can make that work right don't need advice from the forum. You are certainly not going to get it right. As I said before. Garbage in garbage out.
The method described in the OP is nothing like it, don't even go there.
« Last Edit: May 20, 2022, 08:47:38 AM by prj » Logged

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azxuts
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« Reply #17 on: May 20, 2022, 03:30:29 PM »

I appreciate your technical posts prj, and I don't disrespect your insight because you don't say what I want to hear. I suppose we're starting to really go off tangent to the OP, but would you argue that relying on ps_w for MAF tuning is a poor practice? I will admit that my understanding of the load model isn't perfect, but as I understand it, (rlroh_w - rl_w) -> intake manifold integrator magic <-> ps_w -> VE model magic -> rl_w, where, generally speaking, rl_w will be pretty close to rlroh_w in steady state (this is why you say ps_w is partly irrelevant).

In my case, I did not tune relying on STFT+LTFT, rather forcing lambda to a specified value (typically 0.99 or 0.90) and logging lamsbg_w, actual lambda (thru the downstream ADC), ps_w, uhfm_w, nmot, and with enough data from street driving I was able to see where problem areas are hiding, either in the MAF or injector data - the key here being that errors that show up when lamsbg_w gets changed implies a problem in the injector data, while problems that persist implies a problem in the MAF data. The end result is that my ps_w is very close to actual manifold pressure, and whatever lambda I request is the lambda I get. My STFT+LTFT stays within 5% overall in closed loop, which I consider good enough considering how pump gas can vary - maybe this might not be the case on a very high powered car where going 5% lean could result in instant engine deconstruction.

I am a mechanic by trade and do not have access to a dyno or any testing equipment, and this was done some time ago as my first hands on tuning experience, using injectors I got for free and a MAF housing I paid something like $5 for off a Ford F250. Would I do it this way again? No, unless I wanted to double check a tune as it's just about complete. Do I think this could go wrong and give you garbage data? Yes, probably. When I do my turbo ford I do plan on actually testing the injectors I use to get a good baseline for what injector breakpoint, high/low slopes, offset, and all associated pressure compensations before installing them since figuring out injector data from scratch on the car sucks no matter how you do it.
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prj
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« Reply #18 on: May 23, 2022, 04:02:18 AM »

I appreciate your technical posts prj, and I don't disrespect your insight because you don't say what I want to hear. I suppose we're starting to really go off tangent to the OP, but would you argue that relying on ps_w for MAF tuning is a poor practice? I will admit that my understanding of the load model isn't perfect, but as I understand it, (rlroh_w - rl_w) -> intake manifold integrator magic <-> ps_w -> VE model magic -> rl_w, where, generally speaking, rl_w will be pretty close to rlroh_w in steady state (this is why you say ps_w is partly irrelevant).
Exactly, the only thing that the manifold model does here is some filtering, but rlroh_w and rl_w are almost equal. The whole rlroh_w thing is a hindsight thing, the ECU was designed speed density first, and then the MAF was tacked on. I would say that ps_w is largerly irrelevant on a MAF based car, because it is used only for a few things like brake booster. Everything else uses load. If ps_w is in the ballpark, then it's good enough. Totally different story on a speed density ECU of course, where the whole calculation matters a great deal, since load is calculated from it. On HFM the calculation is applied to get ps_w from rlroh_w and then the same calculation is inverted to go back to rl_w - you can probably see here that it does not matter a great deal what is in the VE model, as it does not really affect rl_w.

Quote
In my case, I did not tune relying on STFT+LTFT, rather forcing lambda to a specified value (typically 0.99 or 0.90) and logging lamsbg_w, actual lambda (thru the downstream ADC), ps_w, uhfm_w, nmot, and with enough data from street driving I was able to see where problem areas are hiding, either in the MAF or injector data - the key here being that errors that show up when lamsbg_w gets changed implies a problem in the injector data, while problems that persist implies a problem in the MAF data.
This is wrong. Injectors and fuel system are not 100% linear, so no, this does not imply anything whatsoever.
You have no way of knowing if the problem is due to MAF linearization or due to fuel system non-linearity in this instance, and that is the exact moment it becomes garbage in, garbage out.
« Last Edit: May 23, 2022, 04:05:31 AM by prj » Logged

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Leonard-GK
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« Reply #19 on: May 29, 2022, 05:48:58 PM »

Thanks a lot prj.
It helps a lot,good luck with your next life. Smiley
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Cheekano
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« Reply #20 on: June 04, 2022, 05:46:57 PM »

With this method, is the change between TVUB and KRKTE equal? If say you lower TVUB by 2%, do you increase KRKTE by 2% as well?
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prj
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« Reply #21 on: June 05, 2022, 01:01:45 AM »

Definitely not.
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jibberjive
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« Reply #22 on: June 25, 2022, 03:04:39 AM »

Nice post prj.
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TeknoFi
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« Reply #23 on: July 23, 2022, 01:25:03 PM »

Does this assume that the load is directly reflected in the changes in battery voltage? I must be stupid but I don't see any point in this, very bad way to adjust the injectors. Could you please enlighten me.

What I would do is modify the voltage regulator of the charger and add a potentiometer to it and adjust the tvub with it.
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prj
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« Reply #24 on: July 23, 2022, 05:42:23 PM »

Does this assume that the load is directly reflected in the changes in battery voltage? I must be stupid but I don't see any point in this, very bad way to adjust the injectors. Could you please enlighten me.

What I would do is modify the voltage regulator of the charger and add a potentiometer to it and adjust the tvub with it.
I think you need to do some more reading before coming to this topic, this went completely over your head.
I am describing how to get from point A to point B, you don't even know at this point what A and B are...
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