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Old 05-20-2008, 12:20 PM   #1 (permalink)
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Chysler patent raises technical question about injector accuracy

I hope this is an appropriate place for this question. I think it is.

I think a major advantage of MPGuino is that it reads the injectors directly. It's pretty clear that doing indirect calculations based on OBD2 airflow data (e.g., SG) will yield results that aren't always perfectly accurate. And I think a high level of accuracy is actually important, given the intended use of these products.

For example, I would really like to know what happens when I add cargo, or change tires, or drive into a headwind, or do all sorts of major and minor aero mods. I won't have confidence in these observations (and therefore I won't bother making them) unless I have an instrument that delivers impressive accuracy.

I figure reading the injectors is a great way to do that. But I'm posting here because I just stumbled across a patent that raises interesting questions.

The patent was published in 2000, and it belongs to Chrysler. It's called "Method for calculating fuel economy using manifold air pressure (MAP) and fuel rail temperature."

Here's the abstract: "A method for determining an approximate, instantaneous fuel economy of a gasoline powered motor vehicle. The method involves determining a nominal fuel flow through fuel injectors of the vehicle's engine under static pressure conditions and adding to this value a determined additional quantity of fuel flow through the injectors which is caused by dynamic conditions such as engine rpm, vehicle speed, etc. The additional quantity of fuel flow is determined in part by monitoring a pressure drop across the intake manifold of the vehicle. The temperature of the fuel and the octane rating of the fuel are estimated and used to help determine a fuel density value. The fuel density value is then used to determine a total volume of fuel used. The total volume of fuel used is then ratioed with distance information to provide a fuel economy value."

They're monitoring the injectors, but they're saying that some other factors (e.g., fuel temperature and manifold pressure) need to be taken into account in order to improve the accuracy.

Anyway, I just thought this might be interesting to ponder. I'm sure MPGuino is going to have terrific accuracy (at least compared to SG, which is going to be the typical comparison, I think). But questions about this might arise, so it might be good to think about whether there's knowledge in this patent that can be used to improve MPGuino, or to help users understand how to use MPGuino more effectively.

The patent is here: http://www.freepatentsonline.com/6038917.html

I notice there are lots of other patents in this field, but this one struck me as particularly interesting and perhaps relevant to MPGuino.

I'm very curious about what folks think of this.

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Old 05-21-2008, 01:01 PM   #2 (permalink)
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I don't think it means a whole lot other than the fact that they have a patent. What they have their is a complicated way of projecting variations in the amount of fuel that can get pushed out through the injector under varying conditions. Fundamentally, their are probably some variations due to the things they suggest, but all things considered, the fact is that it's a on/off opening, under a relatively fixed pressure, in most cases. Consequently the amount of variation is going to be averaged out, effectively, since the Guino is going to be adjusted based on the amount of fuel actually used, so that the variation is averaged out.

The net result is the absolute, instantaneous figures could have a little variation, but the variation is averaged in and considered, so the instantaneous values include the variation. Consequently, in our use, the detail they are trying to claim a patent on is relatively, largely insignificant. It's sort of like measuring a gallon and then worrying about was that one teaspoon over or under, after you have done 10 gallons. Who cares, it doesn't matter, the overall accuracy is great for what it's used for and additional precision out to 100's or 1000's of a mile is prone to so many minute variables we couldn't track them, identify them or change them, so what?

The fact is that anyone can get file for a patent, on anything. The only real value in having a patent is so you can do something without someone else being able to claim that they have a patent and your infringing. Even if you have a patent and your patent is validated through a court based trial, it is virtually impossible to enforce and anyone can essentially make an end run on the patent by changing some simple, but critical nuance, like the sequence.

For Chrysler, it is probably nice they have the patent. It probably even keeps some attorneys employed. It probably doesn't do much or anything else.
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Old 05-21-2008, 01:32 PM   #3 (permalink)
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It's foolish, like pretty much everything else Chrysler has done.

If they developed their own ECU's, they'd realize that all they need to monitor fuel usage is a little extra code. The ECU already decides how much fuel it injects every cycle, the only thing missing is a routine to track that number.

Of all the parameters that go into determining fuel usage, fuel rail temperature is on the bottom of that list. MAP is only halfway accurate if the engine is at 14.7:1 all the time. That means no injector shutoff, no cold start enrichment, no cylinder deactivation (at least not with open intake valves), no decel lean-out and no WOT. Becoming fixated on one tiny little variable (fuel rail temp) while ignoring everything else that influences fuel usage is penny-wise and pound foolish. Besides, MAP only helps you determine air flow, not fuel flow, and then, only if you have RPM data to go with it!

There's no law against patenting stupidity. Chrysler's (borrowed) money is as green as everyone else's. How about you idiots make something people would buy, like I dunno, an economy car under 3200 lbs without integrated AC outlets and in-dash refrigerators.
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Old 05-21-2008, 02:18 PM   #4 (permalink)
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Quote:
Originally Posted by JohnnyGrey View Post
It's foolish, like pretty much everything else Chrysler has done.

If they developed their own ECU's, they'd realize that all they need to monitor fuel usage is a little extra code. The ECU already decides how much fuel it injects every cycle, the only thing missing is a routine to track that number.

Of all the parameters that go into determining fuel usage, fuel rail temperature is on the bottom of that list. MAP is only halfway accurate if the engine is at 14.7:1 all the time. That means no injector shutoff, no cold start enrichment, no cylinder deactivation (at least not with open intake valves), no decel lean-out and no WOT. Becoming fixated on one tiny little variable (fuel rail temp) while ignoring everything else that influences fuel usage is penny-wise and pound foolish. Besides, MAP only helps you determine air flow, not fuel flow, and then, only if you have RPM data to go with it!

There's no law against patenting stupidity. Chrysler's (borrowed) money is as green as everyone else's. How about you idiots make something people would buy, like I dunno, an economy car under 3200 lbs without integrated AC outlets and in-dash refrigerators.
LOL, I see you are a big chrysler fan too! Of any car company I think chrysler has the most people hating them, maybe VW and their electrics are close. Chrysler has excellent vehicle concepts then screw up the implementation. I wouldn't be surprised if they came out with a Prius killer soon as it would be the right thing to, just like the K-car, and minivans.

It will probably be unreliable but that hasn't stopped millions of people from buying Chrysler products before.
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Old 05-21-2008, 02:40 PM   #5 (permalink)
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Those comments are very helpful. Thanks for taking the time to speak up.

Chrysler has done some wacky things. My dad's '61 Plymouth had a pushbutton transmission. No in-dash fridge, though.

He also swore that he could get 25 mpg with his '66 Dodge Polara, 318 V-8, two barrel carb. But I never personally verified that.
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Old 05-21-2008, 03:08 PM   #6 (permalink)
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Quote:
just like the K-car, and minivans.
Oh reeheeheeheeaally?

Then why do I end up smelling these cars before seeing or hearing them? Seriously, nine out of every ten smoke belching pieces of #*$% on the road are Chryslers. I'm really glad that it took a foreign takeover for them to learn how to make a piston ring properly. Let's not even talk about their head gaskets.
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Old 05-21-2008, 03:22 PM   #7 (permalink)
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Quote:
Originally Posted by JohnnyGrey View Post
Oh reeheeheeheeaally?

Then why do I end up smelling these cars before seeing or hearing them? Seriously, nine out of every ten smoke belching pieces of #*$% on the road are Chryslers. I'm really glad that it took a foreign takeover for them to learn how to make a piston ring properly. Let's not even talk about their head gaskets.
Well, they were very popular when they came out, right? So chrysler had the right ideas just can't build a quality car to save their life...

Even my neon, back in 1995, 136hp or 150hp, fun to drive, looks kinda cute. What did a 95 corolla/civic/sentra/protege clone look and drive like, looked slow and boring and was slow and boring. Great concept but lack of quality killed another good idea...

With the Viper, the SRT-4, their big V8 rwd cars, they created or recreated whole car segments.

The innovation is there, they just need toyota to build them!
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Old 05-21-2008, 04:29 PM   #8 (permalink)
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Quote:
Even my neon, back in 1995, 136hp or 150hp, fun to drive, looks kinda cute. What did a 95 corolla/civic/sentra/protege clone look and drive like, looked slow and boring and was slow and boring. Great concept but lack of quality killed another good idea...
Yes, and what happened to your Neon? How many Neons do you see on the road now despite the swarms that were rolling around in the 90's and early 00's? I could go entire days without seeing/smelling one now. Compare that with all the mid-90's Civic, Corollas, Cavaliers, Sentras, and Sunfires that are still on the road and don't burn oil. What good is 136 horsepower when your car is on blocks all the time? I might only have 115 horsepower, but it's worth never having to check my oil level. When I hit 125K, 4 quarts will be in the pan. On the bright side, if you burn a quart a week, you never really have to do an "oil change".
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Old 05-21-2008, 04:52 PM   #9 (permalink)
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Quote:
Originally Posted by JohnnyGrey View Post
Yes, and what happened to your Neon? How many Neons do you see on the road now despite the swarms that were rolling around in the 90's and early 00's? I could go entire days without seeing/smelling one now. Compare that with all the mid-90's Civic, Corollas, Cavaliers, Sentras, and Sunfires that are still on the road and don't burn oil. What good is 136 horsepower when your car is on blocks all the time? I might only have 115 horsepower, but it's worth never having to check my oil level. When I hit 125K, 4 quarts will be in the pan. On the bright side, if you burn a quart a week, you never really have to do an "oil change".
Might be just my area but I see 95-99 neons all the time here, I actually pass myself in my commute. I do totally agree that almost everyone builds better quality cars than chrysler then and now.

My 95 Peon/neon is alive and mostly well, it just has many small faults or "character"
AC just quit.
Intermitent wipers work intermitently or the control stalk starts smoking.
Leaky window seals over 100km/h.
Leaking oil from the headgasket, cam sensor seal, and a couple other places. (still have to change the oil though!)
Radio is down to one speaker working.
Sagging springs.
Speedo reads 5km/h high.
The ECU has a high pitch whine after you shut off the car.

Some of the faults result in better mileage though, no AC, lower ride height, lower actual speed with the speedometer... It also has a WAI stock!

It has never left me stranded, returns pretty good mileage and the body is in good shape. It also spanked a few "superior" cars at the last autocross so I think I'll keep it while it lasts!
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Old 05-21-2008, 06:00 PM   #10 (permalink)
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I would not be so overly zealous in Chrysler bashing.

The smoke problem, at least from the mini-vans was due in many cases with a Mitusbishi based 3.0 liter V6 engine. A design flaw, in my opinion, was that the valve guides could slide farther into the head, if the engine over-heated. In consequence the valve guide seal would lose it attachment, which in turn allowed oil to leak down the valve guide and into the cylinder. It could be fixed, but you had to pull the heads, get new valve guides installed, which had a groove and a snap ring on the top of the guide to keep it from slipping into the head.

On the other hand, I had a 94 Town & Country that I got rid of at 180,000 miles because I was able to get a 98 pretty cheap. It has the Chrysler 3.8 liter V6 in it, which has given me very reliable service and I've been quite happy with.

As far as the Neon's go, I think their disappearance has a lot to do with their aftermarket value being poor, more than the car's being junk. For the money they cost, they seem to do an Ok job.

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