Future is THIN

Pennzoil motor oil
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quote:
Originally posted by 427Z06:
Actually as heated UEGOs, faster processors, and better sensors are incorporated into more engine control systems, you'll see continuous closed loop operation within seconds after cold start on more and more vehicles.
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That is true. As I said "There are wideband sensors that can actually directly tell the computer what the a/f ratio is, but they are not very common and quite expensive."

Such wideband sensors, capable of giving readings outside of the narrow range a normal oxygen sensor operates in, will reduce the need to operate in open loop. I don't believe they're very common right now, especially since the buzz is all about the planar type oxygen sensor which is still not a wideband sensor, it just heats up faster than the old thimble type. (I thought heated oxygen sensors were standard on most vehicles since about 1992 or so?)
 
quote:
Originally posted by bulwnkl:
What sensor(s) are used to determine that we're accelerating?
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I don't know the specific details of your other questions, and likely they vary from engine to engine or manufacturer to manufacturer (the book I quoted from is Ford-centric), but the process of determining that the vehicle is accelerating is done by a combination of the throttle position sensor, the MAP or MAF sensor, and the sensor (crankshaft/camshaft or distributor pickup) which informs the PCM as to engine speed and crankshaft position.

Throttle position sensor: Increased over normal position for current engine load and speed

MAP/MAF: Reads higher airflow in accordance with increased reading from throttle position sensor

crank/cam/dist pickup: reads increasing engine speed
 
That makes some sense, but really only the crank/cam/dist. pickup would indicate acceleration. The others would only indicate different loads (uphill, downhill, more people & luggage or less, towing a trailer or not). The inherent variability of these factors seems to me to argue against any fuel economy difference due to "acceleration fuel enrichment" relative to how one opens the throttle (short of ~75-90% open), and in any event I have trouble with the notion that the ECU will richen the mixture while in closed-loop in response to a slight to moderate increase in load.

I still call BS on the guy you originally quoted, unless he was referring to the enrichment that takes place at or near WOT.
 
quote:
Originally posted by bulwnkl:
That makes some sense, but really only the crank/cam/dist. pickup would indicate acceleration.
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Yes, but consider the case of going downhill..the vehicle might accelerate, but without a corresponding increase in engine load, there is no need for acceleration enrichment.

You mentioned you wanted some details about how it works. Well, I remembered that the EEC-Tuner website has a sample dump from the A9L computer which is one of the PCMs Ford used in the 88-93 Ford Mustang 5.0. (These dump files are modified and re-uploaded to the EEC-Tuner and the A9L computer then operates using the modified file)

These are some sections related to acceleration fuel enrichment from http://www.eec-tuner.com/biz_html/a9l.eec I removed the tables to save space; you can go that URL if you wish to see them.

GLOBAL_ACCEL_MULTIPLIER # Global Accel pump multipler

ACCEL_ENRICHMENT_VS_TPS # Accelerator Enrichment Multiplier vs TP voltage

ACCEL_ENRICHMENT_FUEL_TABLE # Accelerator Enrichment Fuel Table(lb/min)
 
Thanks for the info and link. I cannot see the stuff in the link (file format issue), but I'll mess around on that site some more.

Just offhand, the 3 items you list above and some stuff I saw just super-briefly on the site seem to be saying something different to me than they do to you. To me, when they talk about accelerator-something rather than acceleration-something, it is performing a function like a carburetor's accelerator pump (witness the "Global Accel pump multiplier"). In a carburetor, this richens the mixture upon opening the throttle plate, but it does NOT continue to provide enrichment. It is a "one-time shot" of extra fuel in every application I've ever seen. It would make the most sense to me that the computer is emulating this same behavior. Like I said, I'll cruise around that site some more and see what I can learn.
 
You might also check out the base fuel table in this document here:

http://www.eec-tuner.com/biz_html/EEC Tuner tuning notes.rtf It's about 5 pages in at the top of a page.

Here's a part of it:

Base Fuel Table (A/F ratio)(Load vs ECT)

At 180F coolant temperature, load % vs. A/F ratio

8% 15.25
15% 15.25
27% 15.25
40% 16
55% 16
70% 14.25
80% 13.75
90% 13.5

It seems as though it starts to richen the mixture above 55% load (the computer interpolates the A/F ratio for loads between 55% and 70%)--I wonder if this is what the author was referring to. It seems to me, based on what I have seen from the Scangauge, that even moderate acceleration results in loads above 55%...unless you shift at higher RPMs, but then that runs contrary to what has always been said to be the best way to save gas, which is to shift at low of an engine speed as possible which makes sense since engines are more efficient at higher loads.
 
I have a very stable route to work and back and have experimented with gas milage over the years to the n'th extent. I have never had a vehicle that got over 20 MPG and my current fleet of 4 cars and an SUV runs an average of 16 MPG.

On individual cars I have run the accelerator as there was an egg on it for a tank or two then run it very hard (just to get up to the posted speed) on the next fills. I have found no difference.

I believe that when you punch it the engine efficiency is higher and you are up to speed in a short amount of time contributing to good performance for the fuel spent.

aehaas
 
quote:
Originally posted by brianl703:
It seems to me, based on what I have seen from the Scangauge, that even moderate acceleration results in loads above 55%...unless you shift at higher RPMs, but then that runs contrary to what has always been said to be the best way to save gas, which is to shift at low of an engine speed as possible which makes sense since engines are more efficient at higher loads.
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I doubt you will take big hit on efficiency until you get close to 80%. It just isn't all that far off stoic below that.

You also need to balance mixture against the differences in efficiency at light and moderate/heavy throttle. The higher efficiency with more throttle will make up for quite a bit of mixture.

3-d BSFC plots I have seen commonly show max fuel efficiency far any given rpm at around 80% load for that rpm. If I had know how hard those plots are to get ahold of I would have coppied a bunch of them before I retired.
 
quote:
Originally posted by brianl703:
You might also check out the base fuel table in this document here:

http://www.eec-tuner.com/biz_html/EEC Tuner tuning notes.rtf It's about 5 pages in at the top of a page.

Here's a part of it:

Base Fuel Table (A/F ratio)(Load vs ECT)

At 180F coolant temperature, load % vs. A/F ratio

8% 15.25
15% 15.25
27% 15.25
40% 16
55% 16
70% 14.25
80% 13.75
90% 13.5

Click to expand...
Would that load% be for a given RPM value, or a % of maximum engine power?
 
quote:
Originally posted by AEHaas:
I have a very stable route to work and back and have experimented with gas milage over the years to the n'th extent. I have never had a vehicle that got over 20 MPG and my current fleet of 4 cars and an SUV runs an average of 16 MPG.

On individual cars I have run the accelerator as there was an egg on it for a tank or two then run it very hard (just to get up to the posted speed) on the next fills. I have found no difference.

I believe that when you punch it the engine efficiency is higher and you are up to speed in a short amount of time contributing to good performance for the fuel spent.

aehaas
Click to expand...
I think another factor that you are finding is that vehicles today are not allowed to run as lean in the cruise mode as they were during the 1970's and early 80's. Running lean is great for fuel economy but horrible for NOx emmission, and NOx is the one that the converters are not yet available for last I knew. NOx is also a major pollutant of diesel motors.

The Honda CVCC style 3 valve 2 chamber per cylinder design is perhaps the most extreme example of NOx in gasoline engines I know of. Anyone remember the lean burn designs that called for plug gaps of 0.080"? We are unable to do this at the moment.

In other words, modern cars are made to run richer when being babied down the road than they could be if fuel economy was the only factor. This is also found for the racers that get extra power leaning out their modern fuel systems on the dyno, its very common actually.
 
quote:
Originally posted by oilyriser:
Would that load% be for a given RPM value, or a % of maximum engine power?
Click to expand...
It's for a given RPM value. Or, put another way, a % of maximum engine power available at the particular RPM it's at. 100% load would be at wide open throttle.

My Contour idles at about 20% load at 700RPM.

I have no idea about the Mustang because Ford didn't think to put a "DCL" data output on the computer until the '94 models, and even if they did nobody has bothered to make much in the way of aftermarket tools to read it since OBD-II came only 2 years later.
 
Nickmckinny,

I have wondered what happeneed to that cvcc engine design that was so well aplauded when it first came out. Are you saying that the nox was so high that is what killed this design? I oten wondered what happened to it.

Tom
 
Well... I guess from all this "thin" oil discussion the conclusion is that we should move to -30w-10w as soon as it becomes available... After all, thinner is better, right? Heck, maybe the future is compressed air instead of oil? That's about as thin as you can get, isn't it?
 
quote:
Originally posted by 427Z06:

quote:
Originally posted by rainman:
Heck, maybe the future is compressed air instead of oil?
Click to expand...
They're already working on such a design for turbine engines.
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Don't mean to drift OT
grin.gif
, but air bearings have been in use in turbine applications for some time now. My company uses them on some of our expansion turbines for refrig loops.
G/luck
Joel
 
quote:
Originally posted by rainman:
Well... I guess from all this "thin" oil discussion the conclusion is that we should move to -30w-10w as soon as it becomes available... After all, thinner is better, right? Heck, maybe the future is compressed air instead of oil? That's about as thin as you can get, isn't it?
Click to expand...
The reality is the thinnest oil that the engine lasts as long as reasonably required. You still have to have the proper pressure so that sets the limit to how low one can go.
 
OT, but did anyone watch the Italian GP this morning? In an interview with the Shell lubrication engineer for Ferrari, he held up an oil sample from a few races ago to show the camera. It easily sloshed around in the little bottle and looked VERY thin. He was just sitting at his desk with the bottle on the desk, so I'd assume that it was at room temperature.
 
The rumor is that the Shell oil you saw is 2w-5. One of those transporters is a complete Shell lab with the ability to look at samples and mix small batches of oil on the spot. During a race weekend there are always people going through the trash cans and dumpsters looking for information. Dumpster diving is a job for some people.
 
quote:
Originally posted by LarryL:
The rumor is that the Shell oil you saw is 2w-5. One of those transporters is a complete Shell lab with the ability to look at samples and mix small batches of oil on the spot. During a race weekend there are always people going through the trash cans and dumpsters looking for information. Dumpster diving is a job for some people.
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I believe it. It was surprising how easily it sloshed around in the plastic container and was obviously extremely thin oil. 19,000+ rpms and all that HP/heat being protected by 2w-5. Wow.
 
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