Mike wrote:bulls in transit wrote:How is having no power rolling backwards downhill safer than having no power rolling forwards downhill in a van?
Check out who the op is
I didn’t say that.
Here’s the logic behind it that the engineers
should follow.
We all know that running out of diesel is bad because it lets air in the system, which is hard to get out, especially on some models like Mk6.
So the ecu protects from that by making the engine run rough when it detects a low fuel value from the sender (which is just a float valve).
It is also obvious that losing power while trying to go up a hill (say for just another few hundred meters to reach top, and choose a spot to safely park) would be not only inconvenient, but a hassle, and quite likely dangerous.
It is equally obvious that running out of power, either via the ecu cutting back, or just no diesel whilst at high speed on the highway, say several lanes over, and perhaps in an area without safe stopping areas is unsafe.
It is also obvious from how the system is designed that the vehicle will “think” it is lower in fuel, relative to the reference position of flat and level, if it is on an angle: it could be designed so this was while going/parked uphill or going/parked downhill.
And sure, if you don’t fuel in, at some point you will run out.
But by good design you can make it less likely to happen when going uphill.
All those are very obvious, i trust nobody is confused about any?
Not even BJT?
No?
In the Mk6, and probably all other Transits, the suction is in the middle area of the tank, and the sender/float valve is in the front half.
So that has the effect of both sending a low fuel signal sooner when either going uphill or when you park uphill than when on the flat and level.
Note i said
soonerYes?
Well, my point is that if you are going along and start to go up a short quite steep hill, you don’t want to all of a sudden lose power and stutter to a halt....and then have some other White Transit driven by another inmate ram into you when you suddenly slow down just as they revved higher to get up the hill.
Yes?
If instead you had a low fuel signal sent while going downhill, and the ecu cut back power, is not as big a deal. You don’t NEED as much power, Mr. Gravity is your friend. And the white Transit driven by BigJohnThomas who is tailgating you in a rush to get to church is less likely to run into you, because he has not had to rev up, but in fact ease off a bit.
Due to Mr. Gravity.
So in the next short while you manage to get down the hill and pull over, even in limp mode, both in a safer place, and without some tailgating idiot embedded in your rear.
Like if you are low in fuel, you WILL run out at some point. So you do want a warning. But you don’t want it to make things MORE dangerous.
It seems pretty obvious that having your ecu cut out whilst going uphill is a BAD idea.
In addition it would be best to pull fuel from the rear of the tank to enable this to work better too.
As far as parking, well if you don’t realize you are so low, and you do park facing uphill, and it won’t restart, well not even BigJohn can help you....is hard to get out of a tight spot by going backwards.
If you park facing downhill, well is also a hassle to not be able to start, but at least you could coast out using Mr. Gravity, and maybe BigJ’s wife to help push who you happen to have on speed-dial, and coast to bottom of the hill, where you then do have enough fuel to allow it to start and run maybe a few km to fuel. Or far enough to let you get towed (or given fuel) by RAC for free (they only tow if a distance from your residence).
So that is the design process that Ford should have gone through.
And sure you are not supposed to run out of fuel, but as they say sh*t happens, and fuel gauges can become faulty. And the point of good engineering is to design fail-safe if possible.
In a top notch engineering design company you have a Design Review Meeting where you put up the proposed design, and people go through it to look for stuff like this. I suspect Dearborn doesn’t have very well run Design Review Meetings.