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Old 10-01-2006, 08:50 PM   #1
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Wanting to Confirm/Bust the HAI

So, I've been fooling with this Hot Air Intake for a long time now and I just don't know how to quantify it into some data that will confirm or bust the mod. In addition to the ScanGauge, I have a data logger (Davis CarChip E/X) that uploads into the computer, and graphs display results. I've always noticed that the hotter the air, the lower the "Fuel Trim", meaning it's running leaner.

So, is there another variable I should check to confirm or bust it? The logger collects: Vehicle Speed

Engine Speed

Throttle Position

Coolant Temperature

Engine Load

Intake Manifold Pressure

Air Flow Rate

Intake Air Temperature

Timing Advance

Short Term Fuel Trim

Long Term Fuel Trim

O2 Sensor Voltage, and

Battery Voltage

Which of these data points can be collected to help with this? Speed is automatically collected, plus you can selected up to 4 more variables. I tried it tonight, but I couldn't get the air cold enough -- more tinkering is needed.

RH77
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Old 10-02-2006, 12:10 AM   #2
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Hi rh77 -?In addition to the ScanGauge, I have a data logger?

Your in a prety good situation to do this sort of experiment as you can see more information as to whats going on.

What ide try is this.

Measure the intake temp and the fuel trim with the hot air intake on and see what the resistance of the air temp sensor is reading.
If the logger doesnt give this exact OHM figure you might need to measure this manually with a high imperdance digital multimeter as you drive.

Then , take off the warm intake and alter (with resistors) the signal on the intake temp sensor to match what it read when the hot intake was fitted.
This will simulate the temp sensors hot air reading.

Then drive again and note the mixture readings.

?If you do this rite? , it will confirm if the hot air has just altered the signal from the intake sensor and the computer has given the correct mix to suit or if something else is going on.

Problem is tho , that you will be telling the computer that it should give less fuel based on what the temp sensor is saying because hotter air is thinner air and thinner air is less air.
To keep the correct mix with less air the computer should give less fuel.
BUT..
When you do this test you will in fact be drawing in cold air (more air) and the O2 sensor will see a very lean mixture.
So it will probably self adjust and add more fuel.

Because of this it will probably show better FE with the hot air intake air intake., but really all this interaction wil make the result inconclusive.


PS , I believe that the hot air intake mod does work , but a similar result can be got from altering the intake sensors output by a SMALL amount.
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Old 10-02-2006, 07:31 AM   #3
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Quote:
Originally Posted by onegammyleg
?If you do this rite? , it will confirm if the hot air has just altered the signal from the intake sensor and the computer has given the correct mix to suit or if something else is going on.

Problem is tho , that you will be telling the computer that it should give less fuel based on what the temp sensor is saying because hotter air is thinner air and thinner air is less air.
We've found that this works for some models, especially some Saturns. I don't like to "trick" the ECU into thinking that it has leaner air, otherwise I might get some nasty detonation in the lean-burning conditions. I do have to use at least 91 octane with the HAI, or else I get ping under load. The other question is: will the investment of premium fuel offset the FE and/or emissions to be worthy?

Good thoughts tho...

RH77
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Old 10-02-2006, 12:37 PM   #4
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I'm gonna go with probably because the difference between 89 and 91 is ~4-5%, little less actually. I've seen a poster on the cmpg forums claim that the IAT resistor dropped the fuel consumption at idle in half, and lowered the consumption cruising at 35mph by a significant amount as well. If gas was $1 a gallon, probably not, but now, if the IAT mod nets a +5mpg increase while still allowing you to drive normally, then the ~10+% increase in FE is worth the 3-4% increase in price.
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I think if i could get that type of FE i would have no problem driving a dildo shaped car.
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Old 10-02-2006, 01:04 PM   #5
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Worth it.

Quote:
Originally Posted by omgwtfbyobbq
I'm gonna go with probably because the difference between 89 and 91 is ~4-5%, little less actually. I've seen a poster on the cmpg forums claim that the IAT resistor dropped the fuel consumption at idle in half, and lowered the consumption cruising at 35mph by a significant amount as well. If gas was $1 a gallon, probably not, but now, if the IAT mod nets a +5mpg increase while still allowing you to drive normally, then the ~10+% increase in FE is worth the 3-4% increase in price.
I figured that the Premium wasn't costing me any more, but I am hopefully emitting less -- which is one of my GS Goals.

Someone suggested to me to compare the ignition timing vs. the fuel trim to see if that would effect it.

Before I bought the ScanGuage, I had this OBD-II logger. So last Winter I noticed every time that when my half-arse HAI came loose and cold air was introduced, the trim would go up into "richer" territory. The problem is that now, even at night it's not getting cold enough to test -- I'm still about 40-degrees over ambient. My airbox is a tad screwed-up, I will admit. I'll need to go in there and seal some things up and try it again.

The problem is, I can't monitor the ScanGauge and log data at the same time -- same port -- so I'm flying blind after I hook up the logger. I'll tinker tonight, and run some more tests.

Any requests on the variables tested? Clearly IAT, Fuel Trim, and what else -- 2 more variables can be added from the list.
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Old 10-02-2006, 01:49 PM   #6
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Manifold temperature. That plus IAT should give you a ballpark for volume. In terms of emissions, by increasing efficiency you're definitely lowering carbon dioxide emmited, but otoh, if running lean, NOx emissions spike, so you're possibly helping more on the macro scale (reducing GHGs), but maybe emitting more on the micro scale (local pollution).
There seems to be two ways around the whole IAT deal...
-Fooling the IAT sensor by putting a resistor in, car runs lean/retards timing.
-Actually routing warmer air into the intake.
-Combo of both.

Ideally, if the air is just warmed, there shouldn't be pinging, because the ECU will retard timing/ reduce fueling so that normal combustion happens, but this is the purpose of the EGR, so it probably wouldn't show much benefit. If the car is running leaner via IAT resistor, or the ECU not being about to keep up with the hotter air, then GHG emissions drop even more, but NOx emissions/pinging increase. So... it's a trade off?

What you should do is what MetroMPG did and do a couple bidirection runs with a WAI and a CAI. His car didn't seem to respond because most cars with an EGR system will have it on during cruising and any change in IAT is minimal compared to the increased heat from the exhaust via the EGR system. I suppose the best wa would be to fiddle with the EGR system, but that would probably require SAFI as well. Actually, iirc the EPA tested a turbocharged SI engine with high rates of EGR and found better efficiency than the current TDIs exhibit, with much lower emissions levels. Hmm.. sounds like a really cool project. Buy a spare engine, turbo, wideband oxyen sensor, and megasquirt or whatever, then tune it with high EGR until fuel consumption at various loads, probably emphasize 1.5-3k rpm, is minimized, then drop it in your car and see what your mpg is.
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I think if i could get that type of FE i would have no problem driving a dildo shaped car.
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Old 10-02-2006, 02:36 PM   #7
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I found that there is a sweet spot so to speak with the WAI on my car of about 120 IAT. Above that the timing starts to get retarded and the FE goes down. Running a higher octane did help with the max temp I could run before the timing would start to retard but the increase in temp did not relate to an increase in FE. I try to keep it between 110-125. With the belly pan I have to remove the WAI if the temps are going to be above 90 because the IAT gets to warm. I just installed it again now that the temps have dropped.
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Old 10-02-2006, 09:21 PM   #8
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OK, I went out tonight and tried like crazy to get some cool temps into the intake. I can't consider it as a conclusion, but it's taken some wind out of the 'ol sails...

I crunched the numbers manually because the dumb program has no "export" function...

Conditions:

*Same driving loop of approximately 10 miles
*Acceleration was consistent at 25% throttle up to 55 mph, upon which the cruise control was engaged.
*Variable mismatch: the hood was unlatched to allow for the modified intake (to the first safety latch so the hood wouldn't fly up, Tommy Boy style -- which had to have created additional drag).

*
Test A: High Intake Air
Intake Air Temp Average: 125.9F
Ignition timing Average: 24.3
Fuel Trim Avg: -5.75%
FE: 27.3 MPG

*
Test B: Lower Air Temps (still too hot out, but...)

Intake Air Temp Average: 108.4F
Ignition timing Average: 29.6
Fuel Trim Avg: -4.69 %
FE: 33.6 MPG

Now what do you make of this??? There has to be a "sweet spot" because super-low temps would, hypothetically, kill trim and FE.

Conclusion: On this test, ignition timing retarded considerably with a negative effect on FE, as IAT was increased.

RH77
???????
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Old 10-03-2006, 10:16 AM   #9
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Quote:
Originally Posted by rh77
OK, I went out tonight and tried like crazy to get some cool temps into the intake. I can't consider it as a conclusion, but it's taken some wind out of the 'ol sails...

I crunched the numbers manually because the dumb program has no "export" function...

Conditions:

*Same driving loop of approximately 10 miles
*Acceleration was consistent at 25% throttle up to 55 mph, upon which the cruise control was engaged.
*Variable mismatch: the hood was unlatched to allow for the modified intake (to the first safety latch so the hood wouldn't fly up, Tommy Boy style -- which had to have created additional drag).

*
Test A: High Intake Air
Intake Air Temp Average: 125.9F
Ignition timing Average: 24.3
Fuel Trim Avg: -5.75%
FE: 27.3 MPG

*
Test B: Lower Air Temps (still too hot out, but...)

Intake Air Temp Average: 108.4F
Ignition timing Average: 29.6
Fuel Trim Avg: -4.69 %
FE: 33.6 MPG

Now what do you make of this??? There has to be a "sweet spot" because super-low temps would, hypothetically, kill trim and FE.

Conclusion: On this test, ignition timing retarded considerably with a negative effect on FE, as IAT was increased.

RH77
???????
Mine acted the same way when the IAT gets up around 130 or higher the FE drops like a rock.
I think with the temps the way they are you need to try again without the WAI because you already have it. Here's a couple of things you can try that I used for my commute during the summer to keep the IAT in my sweet spot. My airbox is set up so that the filter sits on top and there a a huge space under it that I put 3 glasses of ice in. This would last 30 minutes at 100+ for the commute. I quickly got tired of that. So I tried a wet sponge down there and that would last about 1.0. and keep the IAT under 125. The wet sponge acutally keep it the same IAT as the ice as long as the car was not idling. But now you added increased humidity to your equation The spong did the trick and keep the temps low enough that the timing was not retared. YMMV
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Old 10-03-2006, 11:11 AM   #10
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I have found with my Civic if the air is to warm it hurts its mpg. I was running about 119f air intake yesterday on I-40 and struggling to keep 50 mpg. I stoped and sliped the stock tube back on the air box to use the OEM intake system. Air temps droped to 96f and mpg game up to 54 mpg.

We are having temps during the day in the low to mid 90's right now in Okiehoma. I will pull the intake tube off when temps drop back down to the high 40's and 50's here in a week or so.

My gut is telling me. My Civic dosent like intake air temps above 105f nor below 60f.

This past summer with air temps at 100f to 105f it seemed to have trouble with getting good mpg. With saturation of the intake system in OEM config good mpg was hard to get.
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