Fuel pressure comp/safety

Testing and development of Megasquirt 3

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93supercoupe
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Fuel pressure comp/safety

Post by 93supercoupe »

Currently, we have fuel pressure comp for fixed pressure regulators.

I'm wondering if there's a possibility of getting a fuel pressure comp/saftey for a normal rising rate regulator.

With compensation, we could potentially have a saftey. If the comp exceeds a certain amount, it triggers a safety. I know in my car, I will see compromised pressure far before I see it in the o2 sensors.

I'm at the limits of my pumps and I constantly have to watch the fuel pressure to avoid hitting the afr safety. But the problem with afr saftey is that it's reactive. The motor had already gone lean by the time it gets triggered.
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nvr2fst
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Re: Fuel pressure comp/safety

Post by nvr2fst »

I agree this is a must. I can't think of many that do not use a FP compensation in some way. In high power cars or cars on the limit, this missing feature can be expensive.

-Josh
Matt Cramer
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Re: Fuel pressure comp/safety

Post by Matt Cramer »

nvr2fst wrote:I agree this is a must. I can't think of many that do not use a FP compensation in some way. In high power cars or cars on the limit, this missing feature can be expensive.

-Josh
The current code will work for a regulator that either uses a fixed pressure or a 1:1 rate. It currently does not support regulators that add higher rates.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
cj.surr
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Re: Fuel pressure comp/safety

Post by cj.surr »

Matt Cramer wrote:
nvr2fst wrote:I agree this is a must. I can't think of many that do not use a FP compensation in some way. In high power cars or cars on the limit, this missing feature can be expensive.

-Josh
The current code will work for a regulator that either uses a fixed pressure or a 1:1 rate. It currently does not support regulators that add higher rates.
How is fuel pressure comp enabled for a vac referenced, 1:1 regulator? In "Fuel Pump and Pressure" I have my fuel pressure sensor configured and working, but I don't see anything being done on the fuel pressure correction datalog field.
Matt Cramer
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Re: Fuel pressure comp/safety

Post by Matt Cramer »

Please post a data log and MSQ - I'd like to see if the ECU has any reason to think the correction is needed.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
93supercoupe
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Re: Fuel pressure comp/safety

Post by 93supercoupe »

Matt Cramer wrote:
nvr2fst wrote:I agree this is a must. I can't think of many that do not use a FP compensation in some way. In high power cars or cars on the limit, this missing feature can be expensive.

-Josh
The current code will work for a regulator that either uses a fixed pressure or a 1:1 rate. It currently does not support regulators that add higher rates.

Thats great to hear, but if thats the case, we might want to change to wording and labeling to say that in the menu/tool tips.
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cj.surr
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Re: Fuel pressure comp/safety

Post by cj.surr »

Matt Cramer wrote:Please post a data log and MSQ - I'd like to see if the ECU has any reason to think the correction is needed.
Ok, here's a log and msq. Around 110s you can see fuel pressure drop about 5 psi during a pull and "fuel pressure cor" does not change from 0. Please let me know if I'm looking at the wrong value or I have something set up incorrectly for my 1:1 vac referenced setup.
Attachments
E28Tune.msq
(277.71 KiB) Downloaded 26 times
2017-09-29_12.17.37.msl
(1.45 MiB) Downloaded 26 times
Matt Cramer
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Re: Fuel pressure comp/safety

Post by Matt Cramer »

You may need to enable a custom correction curve. It looks like the current settings don't enable correction if set to vac referenced.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
93supercoupe
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Re: Fuel pressure comp/safety

Post by 93supercoupe »

Compensation for a 1:1 regulator (the most common regulator on EFI) should be a standard feature.

Also, a saftey based around the compensation would be nice.

I would much rather have my car shut down because MS3 was adding 25%+ for fuel pressure comp rather then waiting until the engine goes lean enough to hit AFR saftey.
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93supercoupe
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Re: Fuel pressure comp/safety

Post by 93supercoupe »

Any thoughts on this?
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wes kiser
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Re: Fuel pressure comp/safety

Post by wes kiser »

What are you wanting that is not already there? The custom correction curve will give you what you want for a rising rate regulator, and the pressure safety simply needs to be turned on.

It will then follow the safety shutdowns tuned/setup in the AFR safety menu when fuel pressure shutdown parameters are met. The only piece that will not is the safety will not reference (with load) what you have setup in the customer correction curve for the rising rate regulator, and you would to be forced to increase the rail differential to make it the value you wish to see at full boost.

It is relatively unusual to see some one running a rising rate regulator with a standalone ecu. What is the "rate" on yours?
86 Rx-7, swapped to 2.3 ford turbo (BW EFR 6758), ms3/ms3x sequential fuel /waste spark, ls2 coils
88 Tbird 2.3t, Microsquirt Module (PIMP), TFI ignition
93supercoupe
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Re: Fuel pressure comp/safety

Post by 93supercoupe »

The regulators im working worth are all 1:1 ratio.

Maybe some of my request exists already?

A. Where is this custom correction curve?
B. If it doesnt follow this curve, then it can only be used for a set MAP? With varying boost targets, that doesnt seem like it would be usefull
C. In any case, theres still no compensation for fuel pressure. A saftey is great, but a saftey and compensation is better.
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wes kiser
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Re: Fuel pressure comp/safety

Post by wes kiser »

What you want is already 100% there in the fuel pump and pressure tab. I caution against using the correction. Undamped fuel pressure is normally too dynamic for this to really be useful for the small corrections you would need in a 1:1 vacuum referenced scenario. It is more intended where the fuel pressure is not vacuum referenced, so substantial corrections are required. Sufficiently damped the correction will also be "damped" and behind.

If you still want the correction, enable the correction. Select custom curve, and enable the safety. My above comments have nothing to do with the ECU's code and capabilities, and are more rooted in my physical observations in every instance I have ever had fuel pressure available as a logged channel.

Regarding your comment above, it is not set for a fixed MAP, it is set for a fixed Fuel Pressure/MAP delta. This is what the 1:1 regulator does, is attempt to maintain this rail differential.
86 Rx-7, swapped to 2.3 ford turbo (BW EFR 6758), ms3/ms3x sequential fuel /waste spark, ls2 coils
88 Tbird 2.3t, Microsquirt Module (PIMP), TFI ignition
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