Intake Air Temp resistor experiment. - Page 7 - Fuelly Forums

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Old 07-10-2007, 10:40 AM   #61
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Scangauge takes its readings from the computer, not its own sensors. IAT would be used to calculate how much air is coming in, so the scangauge would be fooled by this. Once the car goes into closed loop, it really only looks at the O2 for a fuel/air mix. The IAT tells it air density, but that only matters on warmup. Once the O2s take over, the computer doesn't need any other inputs. The scangauge would be fooled since it takes several different readings to calculate a guess at the mileage based off an algorithm, not an actual measurement of fuel economy. Skew one number, and the answer is wrong.

Tricking the computer is never a good idea either. The computer needs to see accurate readings, or you will suffer the consequences. Those of us from the high performance world learned of this. JET Performance sells products designed to fool the computer to make more power, and their products work. For about 6 months. By then the toll has been taken, fuel economy is down the toilet and in the trap, and the engine and emissions systems start showing the damage to be had from running rich constantly.

The only way to properly alter the fuel/air mix is to install wide band O2 sensors with a computer program that can handle them, that also allows you full programmability. This, combined with an EGT gauge on each exhaust manifold (if you have a V style engine) is the proper way to make the adjustment. The resistor mod has been laughed at and derided on the hi-po side for years now as a false way to power. It will also be a false way to fuel economy.

The cats only cut NOx if the mix is around 14.8 to 1, so lean burn meams more NOx. One or the other right now. The Honda Insight has a band-aid fix for this, the cats will actually store excess NOx generated in lean burn, then switch to normal burn to convert the NOx. I'd have to wonder though, if the increase in NOx production were offset by the decrease in fuel used on a per-mile basis. If you produced more NOx per gallon burned, but less NOx per mile travelled, then you'd produce less NOx overall on a specific trip by burning lean. And, Nox production is reduced by running lean, not eliminated, so a longer plat/rhodium element might make up the difference.
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Old 07-10-2007, 01:28 PM   #62
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interesting hypothesis that one of the production for mile of Nox, but unfortunately, a vehicle, in order to march to the same speed, needs of the same power (equal fuel amount), with lean carburation or stoichiometric carburation.
And that fuel, because of the lean carburation and the high temperatures of combustion, will tie with the azzoto in marked measure regarding the same stoichiometric motor.
on purpose of IAT: this sensor, is not used from ECU only in phase of warmup, but also at full throttle, when the engine, works in open-loop (rich mixture).

ciao

fabrio
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Old 07-10-2007, 02:06 PM   #63
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Nah, at lean mixtures, the engine is actually more efficient. That is why a lean mixture is desirable (for high fuel economy) in the first place.
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Old 07-10-2007, 06:25 PM   #64
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Quote:
Originally Posted by usedgeo View Post
My Intake Air Temperature resistor EXP

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Intake Air Temp resistor experiments
Copied from general discussion.

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I saw some postings and some mentions but not too much on IAT resistors. Almost everytthing on the net is about more power not fuel economy. I apologize if this has been beat to death years ago.

I just went for the gold. I put in the lowest resistance that the computer would accept without setting a code for Intake Air Temp out of range and compared that with a 10k resister. Here is a little range of experiments and the intake temp I see on the Scangauge. I just used the nominal values of the resistors rather than measuring them. A co-worker tried to tell me about these "chips" a year ago or so and I just totally discounted it. This is darn near the stuff of urban legends. These resistors are 99 cents for a pack of five at Radio Shack. I have never done so much so cheaply before in my life. This is on my 2001 Saturn SL.

10k ohm IAT 28 F
940 ohm IAT 198F
136 ohm IAT 233 F this is two 68 resistors in series.
068 ohm IAT 279 F set an out of range code.

I did an ABAB experiment on the same 8.5 mile loop trying to drive identically. The lights did not cooperate 100% but I judge the experiment valid. The two runs with the 10k ohms were 43.3 and 44.1 mpg. The two runs with the 136 ohms were 61.0 and 63.9 mpg. The average speeds ranged from 29-31 mph. The difference between the average mpg's is 18.75 mpg giving an increase of 43%. The 10k ohm resistor was a slight handicap as the actual temp was 40 F. It was not far off since when I filled up yesterday my tank average was 46.2 mpg and this is just a little better than the 43.7 average of the two 10k runs.

Summary
136 ohm 61.0 mpg
10k ohm 43.3 mpg
136 ohm 63.9 mpg
10k ohm 44.1 mpg

Average difference 18.75 mpg or 43% using the 10k ohm mileage as the base.

I then went out on the freeway and made a 16 mile total loop at 60 mph and got over 60 mpg without any engine off coasting. I just drove easy. I did a bit of idle coasting on the last bit coming home as I could see the average was at 59 and wanted to break 60 mpg.

This morning I did the trip to work starting with a cold engine, I did not need to go to work it is just a familiar route. Against the slight grade and more than slight wind I made 53.8 mpg to work on the freeway at 61 mph. There was no drafting. The instantaneous mileage was between 55 and 60 mpg. I never shut off the engine but reset the current trip at work and started home. I came home on secondary roads so I could drive slower and pulse and glide with the wind to my back. By the time I got to near 1/2 way home my average was 112 mpg. I then lost a bit on as the lights would not turn green until I triggered them myself in the light Sunday morning traffic. I had to get into 2nd gear at several lights. At the stop sign at one road I botched the takeoff and lost about a mile per gallon. I only mention this because the trip home averaged 99.6 mpg. Darn it all anyway. The round trip averaged 70 mpg at an average speed of 40 mph. Here is the "today" summary:
70 mpg
40 mph ave
63 max
28.7 miles

My car obviously has a sensor that tells it when I am in fifth gear. The instantaneous mileage makes a distinct jump now when I hit fifth gear. Something beyond the usual expected with a shift. I can accelerate decently on a slight upgrade at 40 mph in 5th gear and get 50-60 mpg during the acceleration. This does more than just adjust the timing. I can watch the timing and while it changes some with the resistor the change is not that great and something else is going on. Some think it leans the engine out but it is running closed loop. My current theory suggests EGR. I have run engines lean and ruined one turbo 2.3 Ford engine running it lean. This does not feel lean. Drivability is not suffering in the least. I am excessively short shifting to get into fifth gear as soon as I can because I see the immediate benefit.

The only aero mods to my car are blocking the grill and removing the spoiler. I have not even proven that removing the spoiler is a good thing.

This is pretty unbelievable. Nothing will be really confirmed until more distance passes and I have to fill up and check the calibration again on the Scangauge. Last check was within 0.5% yesterday. I hope this is for real. It sure looks that way. I suspect that the exhaust temp is probably not warm enough to keep the catalytic converters on line. Just speculation at this point.

If someone else was writing this I would not believe it either.

Ernie
can you give us the stripe configuration for the different resistances you used?

940 ohm
136 ohm=2 x 68 ohm
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Old 07-10-2007, 08:29 PM   #65
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Please don't overlook the post where I said that the results were all instrument error. I guess you haven't. I have ordered an LC1 wide band O2 sensor and controller but have not installed them yet.

http://www.innovatemotorsports.com/products/lc1.php

At true high intake temperature, above 180 F, the car appears to miss a bit during light acceleration. It still indicates closed loop so I do not have that completely explained yet. In any case the mileage is pretty good feeding the engine hot air. The plugs are pretty white but the slight miss could be from lots of EGR rather than a lean mixture. I expect the Somender gooves will have an effect on that miss and loss of torque. That project starts tomorrow .

68 ohms blue grey black gold. Two resistors in series for 136

470 ohms yellow violet brown gold. Two resistors in series for 940

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Originally Posted by wireless0ne View Post
can you give us the stripe configuration for the different resistances you used?

940 ohm
136 ohm=2 x 68 ohm
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Old 07-11-2007, 05:05 AM   #66
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Originally Posted by fabrio View Post
interesting hypothesis that one of the production for mile of Nox, but unfortunately, a vehicle, in order to march to the same speed, needs of the same power (equal fuel amount), with lean carburation or stoichiometric carburation.
Heh heh... if that were true then there's no use in trying to get better mileage. And as we all know, there are many variables that affect mileage. Running leaner than normal under cruise will net better mileage as each cylinder is burning less fuel per power stroke.

Quote:
Originally Posted by fabrio View Post
on purpose of IAT: this sensor, is not used from ECU only in phase of warmup, but also at full throttle, when the engine, works in open-loop (rich mixture).

ciao

fabrio
True, but this crowd isn't exactly WOT. I didn't think about that when I was posting.
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Old 07-11-2007, 07:17 AM   #67
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sorry Telco, but I am not sure to have understood well.
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Old 07-11-2007, 07:32 AM   #68
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Originally Posted by usedgeo View Post
Please don't overlook the post where I said that the results were all instrument error. I guess you haven't. I have ordered an LC1 wide band O2 sensor and controller but have not installed them yet.

http://www.innovatemotorsports.com/products/lc1.php
fantastic external AFR supervisor with wide band O2 sensor

Quote:

At true high intake temperature, above 180 F, the car appears to miss a bit during light acceleration. It still indicates closed loop so I do not have that completely explained yet. In any case the mileage is pretty good feeding the engine hot air. The plugs are pretty white but the slight miss could be from lots of EGR rather than a lean mixture. I expect the Somender gooves will have an effect on that miss and loss of torque. That project starts tomorrow .

68 ohms blue grey black gold. Two resistors in series for 136

470 ohms yellow violet brown gold. Two resistors in series for 940
180?F is very high air temperature: in closed loop management, only effected an cospique retard of spark advance, for to avoid knock.
This, is the cause of loss torque in acceleration fase.
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Old 07-11-2007, 08:30 AM   #69
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Quote:
Originally Posted by usedgeo View Post
68 ohms blue grey black gold. Two resistors in series for 136

470 ohms yellow violet brown gold. Two resistors in series for 940
Just to cover the base, for those who aren't aware:

The gold is a "tolerance band." Gold means the resistor's value can vary plus-or-minus 5%, and that's probably what's most readily available. But if the fourth band is silver, that's 10% tolerance -- good enough for the kind of stuff we're doing here. So if you come across e.g. yellow-violet-brown-silver, don't worry: It'll work okay.

There are also 20% resistors and, in the other direction, tighter tolerances down to fractions of a percent. These have a different number of bands -- 20% has no fourth band; tighter tolerances add more resolution to the resistance value before the tolerance band (and sometimes use printed values rather than color codes) -- so if you come across a resistor with "too many" or "too few" bands, that's what's going on. You're not likely to run into this accidentally though, unless you buy a "surplus bag" or "experimenter's pack"... then all bets are off as to what you might find.

Yes, I'm a geek.

Rick
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Old 07-11-2007, 08:42 AM   #70
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Oddly enough my Saturn does not show an ignition retard with hot air. I hope that is not an instrumentation error too . That is why I expect the stepper motor controlled EGR might be a factor. In any case it only acts up during moderate acceleration. If I go on down with the throttle it runs very well. The increased throttle could affect both mixture and EGR. I have never heard the engine ping. If it does I will need to look for the knock sensor too .

Quote:
Originally Posted by fabrio View Post
180?F is very high air temperature: in closed loop management, only effected an cospique retard of spark advance, for to avoid knock.
This, is the cause of loss torque in acceleration fase.
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