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Old 10-02-2005, 11:14 AM   #1
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Default CAI and gas mileage

ive always been under the impression that a CAI improves gas mileage, but i started doing some reading as im finally thinking about getting the one in my sig...and it seems alot of ppl have suffered mileage loss, i figured it was because of their now increased foot pressure but then some people mentioned that the colder air richened the fuel mixture..which would be completely true would it not?

what kind of gas mileage have you all noticed since you installed intakes? and what sort of setup do you have? the one im thinking of getting would be a fender well intake, and appears to be pulling air from outside the engine bay...heres a link http://www.tranzgenic.com/index.php?...ake=Oldsmobile

one of my main reasons for getting this was that when i wasnt enjoying the newfound juevos, id like some better gas mileage. but if its going to kill it ill just stick with what ive got.

id also like to add that my stock airbox actually does pull air from outside the engine bay as well...the end of the airbox "reaches out" behind the headlight through a somewhat sealed off area..so perhaps its pulling in colder air already with just a lot of restriction
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Old 10-02-2005, 11:19 AM   #2
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Well, we have different engines, but when I got my Thrasher CAI, I noticed mileage went up a lot on the highway, not so much in the city. However, my stock intake setup was horrid, and was terribly restrictive.
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Old 10-02-2005, 11:59 AM   #3
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An intake can't richen the mixture for more than the first few miles at the worst. Your O2 sensor won't let it stay that way.

People may have lost mileage due to using a HAI (Hot air intake) as opposed to shielding it.

My mileage went up slightly as did every other car here.
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Old 10-02-2005, 02:31 PM   #4
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If colder intake air doesn't result in a richer mixture, why does the mileage go down so drastically in the winter? I have a 44 mile commute, almost all of which is highway, and my mileage goes from 26-27 in the summer down to 22 in the winter. I realize the warmup cycle hurts but I would think the 40+ miles of highway driving would largely neutralize that. I know things are colder and stiffer but that is a huge drop in mileage and the only thing I can attribute it to is the air temperature.
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Old 10-02-2005, 02:34 PM   #5
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A CAI helps the air get in better thus improving flow.....that is why there is a increase in milage...

as for the winter i was told the reason the milage goes down because the grade of gas is lower in the winter...true or not i dont know

and a CAI with heatshield improved my milage on hte highway
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Old 10-02-2005, 02:52 PM   #6
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Quote:
Originally Posted by Mark Fahey
If colder intake air doesn't result in a richer mixture, why does the mileage go down so drastically in the winter? I have a 44 mile commute, almost all of which is highway, and my mileage goes from 26-27 in the summer down to 22 in the winter. I realize the warmup cycle hurts but I would think the 40+ miles of highway driving would largely neutralize that. I know things are colder and stiffer but that is a huge drop in mileage and the only thing I can attribute it to is the air temperature.
In the winter your mileage is so bad because for the first few miles the car is running rich to warm the engine up faster. Your torque converter also does not lock resulting in higher RPM'*. In the winter time I know that our SSEi can take up to 8 miles before it allows the converter to lock completely. During this time fuel economy is usually 6-8 MPG lower than when the engine is warmed up. During the summer months, the warmup period is usually one mile or less, even without letting the engine warm up by idling before taking off.


Hoov, I'm looking at getting the same intake as you. It'* the only one I've found for our engines. I'll probably cut the pipe to make it not go into my fender though because our engine bays are totally different and it wouldn't even work on my car. I'll just have to find some way to make a box to keep hot air out.
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Old 10-02-2005, 02:59 PM   #7
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Colder intake temps can result in timing advance, not a richer mixture. And Pat'* comment on winter mix gasoline is dead on.
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Old 10-02-2005, 03:04 PM   #8
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Quote:
Originally Posted by willwren
Colder intake temps can result in timing advance, not a richer mixture. And Pat'* comment on winter mix gasoline is dead on.
yes, but, I was just saying mileage decreases in winter also because it takes the engine longer to warm up. The 2000+ will not allow the torque converter to engage for a long time after starting. I've seen it take up to 8 miles on both our 00 SLE and 00 SSEi. Also, while in open loop during warm up, the fuel mixture is rich because the oxygen sensor is basically ignored until closed loop, right?
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Old 10-02-2005, 03:12 PM   #9
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that is really weird i have NEVER had a problem in the cold with TC lock?
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Old 10-03-2005, 10:33 PM   #10
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Quote:
Originally Posted by 1993 SLE
that is really weird i have NEVER had a problem in the cold with TC lock?
it all depends on how quick your trans warms up. once it hits the magic number (i don't remember off the top of my head), the tc can lock up. your driving style has something to do with it, as does the type of traffic you drive in. keeping yourself in place on hills with the tranny, as well as waiting at lights (in drive, foot on brakes) raises the temps considerably faster than just driving on the highway does.

checking on the temp right now...

Quote:
The PCM inhibits TCC/VCC operation until transmission fluid temperature reaches approximately 45C (113F). At this temperature, the PCM will allow the TCC/VCC to engage providing the throttle position, gear range, and other vehicle operating conditions are appropriate.
I'm a little confused on the VCC, because I've never heard it talked about before. From the diagrams I'm looking at, it almost looks like you have a tcc or a vcc, but the manual is reading like you have both... strange. in any event, the vcc is more specific about when it will apply:

Quote:
The viscous converter clutch is capable of applying at approximately 40 kmh (25 mph) providing that the transaxle is in third gear and the engine coolant temperature is above 60C (140F). When the viscous clutch is applied there is a constant (but minimal) slippage between the rotor and the body. Despite this slippage, (approximately 40 RPM at 97 kmh or 60 mph) good fuel economy is attained at highway speeds.

When transaxle fluid temperatures are above 93.3C (200F) but below 157C (315F), the viscous clutch will not apply until approximately 61 kmh (38 mph). If the transaxle fluid temperature exceeds 157C (315F), a temperature switch located in the cooler line will open and release the viscous clutch to protect the transaxle from overheating.
so basically, it has to do with how hot your tranny is. I need to look more into the VCC, because I've honestly never run across it before ( ), but hopefully I've added something to this convo... maybe I haven't

<edit>

looking at the diagrams and reading the text more, it looks very much like the VCC was used before the TCC system. just a different method of doing the same thing, except the VCC has a constant slip (approx 40 RPM @ 60 mph). It does state, however, that it 'provides a smooth apply of the clutch assembly'. It also looks like instead of being an open system, using trans fluid, it'* closed, with trans fluid applying on the outside of the clutch, while internally, it uses silicone fluid.

it would be very interesting to find out what years the VCC was used in place of the TCC, and how they act differently with age...

<edit x2>

some quick googling shows that it may have been a cadillac exclusive system (not sure what years it was limited to) for the VCC... might be interested to see what their VCC feels like compared to our TCC... especially at older ages.
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