oil pressure/fuel pressure safety

Testing and development of Megasquirt 3

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93supercoupe
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oil pressure/fuel pressure safety

Post by 93supercoupe »

I know im beating a close to dead horse on this one because there has been many threads on it, but i feel pretty strongly on this matter.

There are alot of users, including my self, that could really benefit from low oil pressure and low fuel pressure safety systems. Most importantly, low oil pressure safety.

Ive seen some threads go on to explain why this isnt a good idea, and it seems the main reason is for the safety of the user. (so he doesnt get shut down in traffic, or really in any dangerous spot.)

I dont disagree that is a very real problem, but i also think that breaking a motor from intermittent low oil pressure is also a very real issue.

This wouldnt be much different then the systems we already have in place, such as EGT shut down, AFR safety, and coolant temp based rev limit and over boost protection.

All of those are available to any user and could potentially have the same personal saftey issues as a low oil pressure saftey system. But they all will have 1 thing in common, you dont need to use them. They are user configurable.

Im not suggesting that when the systems sees low to no oil pressure, the engine shuts down. But maybe a table like AFR safety, or a single line graph like CLT rev limit where shut down is possible but can also just cut the revs


Maybe there is something right in front of me that im over looking that truly does make this more dangerous and different then the systems we have already. If that is the case, please chime in.
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Re: oil pressure/fuel pressure safety

Post by DaveEFI »

Several UK makes at one time had the electric fuel pump controlled by the oil pressure warning light circuit. Light on - pump stopped. Mainly to cut off fuel supply in event of a serious accident. Later cars used an inertia switch.
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jsiedlicki
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Re: oil pressure/fuel pressure safety

Post by jsiedlicki »

I think this would be a great addition to the "Limp Mode" feature. Currently almost all other sensors can trigger limp mode, MAP, MAT, CLT, TPS, Batt, EGO, Flex, and EGT. As there is already an "Oil Pressure" feature that triggers a warning light, why can't it be added to the list of sensors that can trigger limp mode?
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shainiac
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Re: oil pressure/fuel pressure safety

Post by shainiac »

I would also like to see this feature. Just last year I cracked the engine block at the main oil galley (rotary problems) and instead of having to replace one part, I continued driving for over a minute and ruined virtually every part in the engine and could have damaged the ball-bearing turbo. Something like an oil pressure shutdown or limp mode would have saved me a lot of money. I understand that a warning light could be effective too, but for people who already have the car buttoned up, cutting open the loom, running wires and adding lights isn’t as appealing as turning on some features in TS and being done.
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slow_hemi6
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Re: oil pressure/fuel pressure safety

Post by slow_hemi6 »

Shutdown is really annoying. It got me every time I was under brake and turning into my driveway with engine at operating temp. Only way to alleviate was to set for 10psi. 10psi is not protecting much when the engine is spinning at 6K or more. So a system needs to be more than just a activate below some psi set point and should IMO not kill the engine, just go into limp.
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93supercoupe
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Re: oil pressure/fuel pressure safety

Post by 93supercoupe »

slow_hemi6 wrote:Shutdown is really annoying. It got me every time I was under brake and turning into my driveway with engine at operating temp. Only way to alleviate was to set for 10psi. 10psi is not protecting much when the engine is spinning at 6K or more. So a system needs to be more than just a activate below some psi set point and should IMO not kill the engine, just go into limp.

I agree. It's need to be table like afr safety with rpm X oil pressure and the actions need to be configurable also.
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arran
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Re: oil pressure/fuel pressure safety

Post by arran »

+1 for oil pressure limp mode and a table.

Same for fuel pressure (referenced against manifold pressure), I've got both oil and fuel predsure parameters being logged now and it would be great to be able to use them to improve the durability of my engine
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93supercoupe
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Re: oil pressure/fuel pressure safety

Post by 93supercoupe »

Fuel pressure would be nice but a properly set up afr safety system would catch a significant fuel pressure drop also

Might be a good idea for a motor car maybe?
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jsiedlicki
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Re: oil pressure/fuel pressure safety

Post by jsiedlicki »

Seems to be some definite interest! I would like to see the devs weigh in on this. Hint, hint...
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E30_Driv3r
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Re: oil pressure/fuel pressure safety

Post by E30_Driv3r »

+1 for both of these, it can easily save you from a rebuild if you dont notice you're losing oil/fuel pressure.
MWPau
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Re: oil pressure/fuel pressure safety

Post by MWPau »

+1 for both.
I would also very much like it.
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Re: oil pressure/fuel pressure safety

Post by cj.surr »

I like this idea too, but why not make it for ANY 0-5v input? I'm thinking this would be great for a water injection flow sensor also. Map-able acceptable range by RPM and MAP.
93supercoupe
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Re: oil pressure/fuel pressure safety

Post by 93supercoupe »

Just bumping this to the top to keep it on peoples minds. Hopefully we can get some consideration on this in the next beta release.
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jsiedlicki
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Re: oil pressure/fuel pressure safety

Post by jsiedlicki »

Any thoughts from the developers. It would be nice to hear your opinions on the matter.
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Reverant
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Re: oil pressure/fuel pressure safety

Post by Reverant »

I think the "driver/passenger safety trumps engine safety" argument is invalid.

By the same logic, we should not install fuses in our EFI installation, because if a fuse blows while you are on an intersection, the car will be immobilized and you'll be run over by an incoming truck.

Whereas it's preferable to catch fire from a short circuit (C16 blown anyone?) after you cross the intersection and let your car burn down while you look at it from a safe distance.

Same argument, so why do we install fuses?
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aidandj
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Re: oil pressure/fuel pressure safety

Post by aidandj »

Cars have limp modes all the time. It doesn't need to be a shutoff, but at least some sort of configurable limp mode.
93supercoupe
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Re: oil pressure/fuel pressure safety

Post by 93supercoupe »

Any consideration on this?
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aidandj
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Re: oil pressure/fuel pressure safety

Post by aidandj »

Getting a new built motor together. Would love to have safety features for the new engine.
eMTea
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Re: oil pressure/fuel pressure safety

Post by eMTea »

Already in place in 1.4.1 I think, but only as a waring lamp, not in limp mode.
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Re: oil pressure/fuel pressure safety

Post by jsmcortina »

There's already a min/max curve vs. RPM and has been for a number of releases. It was simple to make this trigger limp mode (done for 1.5.x). How quickly should this respond? The other inputs to limp are on a delay of approx 1 second to reduce the chance of false triggers.

Or should it (optionally) trip the engine kill like AFR/EGT safety?

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