GenVibe - Community for Pontiac Vibe Enthusiasts

I FINALLY got my CAI installed yesterday. Took me about two hours, elapsed time (I took a quick supper break) and finished up in the dark. Nothing like listening to Art Bell to keep you alert!Thank goodness for the install posts here...really helped to see color pics of everything rather than the black&white photocopied pics in the instructions.Question for you other CAI owners: I had to push the filter up the intake quite a bit (about 4") to clear the fog lamp and now it's sitting right on top of it. Is that right? I was afraid that pushing it much further might adversely affect the airflow. (And, no, you don't have to remove the bumper; just remove the lower splash guard and swing it out of the way.)No CEL (yet!). I let it run for about 10 minutes until the engine dropped the idle speed to about 800 RPM. I drove it about 15 minutes after that..including a little highway test. My gas mileage is gonna suck for a couple of weeks! I love that sound at 4-5K!

Yes, I slid my filter on a little more than I think the instructions said, but like you said, you have to in order to get it over the fog lamp. At first I didn't slide it on that much and the filter was bent at an angle. I posted a picture on here and people told me that they slid it on more to get it straight and above the fog light. I don't know if it affects the airflow, I would think it may slightly, but if it does, it's no big deal. I've had mine installed going on two years now and it has been awesome. Enjoy it!

Yep, your filter is fine there, I had to do the same thing. Yeah, good luck getting decent mileage for awhile.

I installed my Injen CAI (RD2075P) yesterday on my 2003 GT. I thought there was too much pipe in the air filter and was restricting the airflow. So today, I went to Home Depot and rented a 4" pipe cutter and cut off 3 inches off the end. It also provides enough clearance from the fog light and makes it easy to install the air filter.BTW. I got it from ebay for $199.99 with free shipping.

I never got decent mileage after my install ENJOY!

I have noticed that some CEL's due to the intake won't show up until after the 4th starting cycle. My mileage has also dropped due to the weight increase in my right foot. I love that sound as well. Have fun!

My cel was brought on by my little short out with the MAF sensor heh... most people dont have any issues and I don't see you having one since you let the engine idle for 10mins before going redline heh.

the only probs most people had with their cai and cel's were ones that blew out their maf's (as mav already stated), had a loose or unconnected hose, or had the TRD cai on the GT model (like I did). of course, i was able to get rid of the cel by adding the unichip.

Did the same thing when installing one on my 2004 Base back in April. No problems. Enjoy!

I think my cel is because I have a '03 gt c.a.i. on an '04 gt. any suggestions there?

What does CEL stand for?

Quote, originally posted by Regize »What does CEL stand for?Check Engine Light. I got one after my Injen CAI install b/c I put the VSV in upside down and had the hoses switched. Make sure the cap is down.

Quote, originally posted by 4X4CHICHI »I think my cel is because I have a '03 gt c.a.i. on an '04 gt. any suggestions there?I think they are the same model, you should be OK.

I was right...my last tank of gas had the worst gas mileage ever (23.4 mpg), but I did top off the tank, so it might have been more like 25 mpg. I'll know for sure after a couple more fill ups.If I behave (yeah right), I really should have about the same mileage; the rpms seem to be below what they used to run for the same speed (about 10% or so).

Nope, more plumbing on the '04

Quote, originally posted by 4X4CHICHI »Nope, more plumbing on the '04Really? Weird. Is it due to the lower emissions stuff on the '04?

Quote, originally posted by ZubenElGenubi »the rpms seem to be below what they used to run for the same speed (about 10% or so).Unless you've changed gears in the tranny then that's impossible.

Quote, originally posted by Pick »Unless you've changed gears in the tranny then that's impossible.Academically, I see your point, but empirically, I really do think the car is running on lower RPMs for the same speed.Suppose, for arguments sake, that the increased air flow makes the engine more efficient (by bringing more oxygen into the combustion process). Why wouldn't that result in a lower RPM level for a given speed?Looking at it another way, if originally, 3000 RPMs in 4th gear could maintain my vehicle at 80mph originally, why shouldn't 3000RPMs in 4th gear with a CAI allow my car to move faster than 80mph?I wish I'd actually noted the rpm-speed ratios before I installed the CAI so I could be sure. Does anyone with an '04 base Vibe want to help me with an experiment? We'd need persons with and without CAIs...

I have noticed that my rpms run a little lower than when I was running the stock air box. The more efficent the engine is, the less work it takes to reach the same speeds hence the lower rpms. That's why high performance oils tend to allow for you to get more hp out of your engine than regular oils. The engine does not have to work as hard and is there fore more efficent at making power. It wont be a great deal but you should see a drop in rpms.

You will waste alot of gas trying to hear that beautiful sound the CAI makes lol

your engine rpms are directly related to your gearing, period. I know you don't believe, but think about a bicycle, the amount of effort required to travel a certain speed in a certain gear will change depending on uphill or downhill, but the pedals are still turning the same speed, it may simply require more or less effort to make them turn the same speed. BUT THE RPM'S will remain constant with the gearing.

I totally agree with the rpms being directly related to your gearing. The additional air from the CAI will not affect your gearing at all. Think about when you are coasting in gear, your wheels are keeping the engine at that certain RPM even though you take your foot off the gas. Now if you were to put on some 14" wheels with low profile tires (if you changed the outer diameter) or had your gearing changed, then you would see some rpm changes.

The CAI has nothing to do with gearing, that I will agree on. Its the simple fact that the engine does not have to work as hard to get the air it needs so it is more efficient at what it does thus the rpms will drop slightly, not talking a great deal. I know from my own experiences that it did change from stock to when I put my CAI on. At 70mph the rpms were around 3500, now its more like 3000.

Quote, originally posted by ZubenElGenubi »Academically, I see your point, but empirically, I really do think the car is running on lower RPMs for the same speed.You are correct, my rpms dropped by by about 500 @ 60 mph after my Cai installation.As far as the CEL, if i cold start my car it will come on in about 3 min.if I warm my car up, then reset the CEL, then restart the car it will stay off all day. I am going to live with it and see if adding the unichip takes care of the issue.

I'm definitely in agreement with Pick and JustinVGT that there is a direct relationship between RPM and MPH. Yesterday, I measured the RPM levels for various speeds and plotted them (see attached graph).The question is whether this plot is different (either in slope or height/intercept) for a similar vehicle (i.e., Base Vibe) with the stock intake.Anyone up to the task of measuring their vehicle's performance? I'm really curious as to the results.

Attached files

Quote, originally posted by iinan »You are correct, my rpms dropped by by about 500 @ 60 mph after my Cai installation.bawahahahahahahaha Now that's funny.

Quote, originally posted by ZubenElGenubi »Anyone up to the task of measuring their vehicle's performance? I'm really curious as to the results.Don't forget that people will need to factor in tire height. That will make a huge difference in engine rpms vs MPH ie: Put on some huge mudgrips and your Speedometer will say you're doing 50mph when you're actually doing 80, or put on some donuts and your speedometer will register 90mph while you're actually only doing 60mph.

Please note: NEITHER Horsepower nor engine load have any effect on your engine RPMS at any given mph, gearing and tire size determine engine RPM!http://www.florida4x4.com/tech/gearcalc ... /rpm.shtml

Your engine RPMs will not be any lower while driving with an aftermarket intake compared to the stock intake. When you are driving 70 mph the wheels which are connected to the drive axles which are connected to the transmission which is connected to the engine are all moving together at the exact same revolutions when you are going 70 mph with or without your intake. Think about it, your engine is connected through the transmission directly to the wheels. Simply letting more air into the engine will not make your wheels spin faster and your transmission spin slower (that is essentially what you are implying). The engine RPM is directly related to the gearing, therefore adding an intake will not affect your RPM or gearing at all. Another thing to think about, I mentioned the coasting earlier. When you coast with the engine in gear, it shuts off the fuel injectors; the car's momentum turning the wheels is maintaining the engine's RPMs. Say you go full throttle to 70 mph in 3rd gear with a GT then completely take your foot off the gas; you would be around 7k RPM. When you take your foot off the gas, the throttle is no longer wide open, therefore it's not sucking in as much air, but your engine will still stay around 7k RPM and will slowly drop as your speed drops ( again MPH and RPM directly related).I have a CAI and cat-back exhaust system and my RPMs never decreased while driving. The only decrease in RPM I have encountered after installing my CAI, along with many others on this site, is the idle speed. It usually stays around 800-900 RPM, but every once in a while does drop to around 600 RPM since I have installed my CAI. I’m just trying to help explain how it works.

The improved airflow into the engine allows for the engine to burn more efficently. This traslates into more power per stroke of the pistons, therefore the engine does not have to work as hard to move the same load. This is all I am trying to say. Yes, gearing in general does have the most effect on rpms. I'm not saying that. Just my observations on the effects of my cai on my car.

Quote, originally posted by theangrydwarf1 » Yes, gearing in general does have the most effect on rpms. .Wrong, gearing and tire size are the only things affecting engine rpm vs speed. Period!How hard your are or aren't having to push the gas pedal to get to a certain rpm and speed only affects your gas mileage. Having more horsepower does NOT lower your rpms at a given speed like some are claiming.

I completely agree with Pick on this. Now with more HP you will reach the rpms faster and accelerate faster, but your rpm/mph ratio will still be the same.What do I know though, I only have a physics degree.

JustinVGT...your points are well-taken and I'm inclined to agree that this is all an illusion on my part. However, I played with several of the RPM calculators you referenced and their results do not bear out to my current observations.For example, the calculator at http://www.csgnetwork.com/multirpmcalc.htmlgives the following results for the givens:Ring Gear and Pinion Ratio: 0.98 (4th gear published ratio for Base Auto Vibe)Tire Height: 24.9 (inches, based on 205/55-16 tire)Transmission Final Ratio: 2.96 (Final ratio for Base Auto Vibe)Calculated RPM @ 65 mph: 2544 Observed RPM: 2500Calculated RPM @ 80 mph: 3131 Observed RPM: 3000Calculated RPM @ 85 mph: 3327 Observed RPM: 3150There is good agreement around 2000rpm/50mph between the calculated values and those observed, but they diverge by about 5% by 3300rpm/85mph. Even if you assume centrifugal tire expansion, the tire diameter must increase from a 24.9" to 26.3" (1.4") to account for the effect, which I doubt is happening at these speeds.Here's another example. At http://www.fordmuscle.com/calculators/r ... iven:Speed: 80mphGear Ratio: 2.96 (again, final ratio for base auto Vibe)Tire Diameter: 24.9Calculated RPM = 3195 Observed RPM: 3000Maybe the calculators aren't designed well enough, but they do not fully support your arguments.Or I'm plugging in the wrong numbers???

I never said you or anyone else was wrong, I'm only stating what I have seen with my own two eyes.

Quote, originally posted by ZubenElGenubi »Maybe the calculators aren't designed well enough, but they do not fully support your arguments.Or I'm plugging in the wrong numbers??? Probably just the speedometer itself reading wrong, most speedometers are not absolutely precise and are usually off by a few percent.

Quote, originally posted by Pick »Probably just the speedometer itself reading wrong, most speedometers are not absolutely precise and are usually off by a few percent.Excellent point, Pick. Just so happened that I tested out the speedometer/odometer a couple of months back and the error was less than 0.5%. I should have noted that.One thing I will do later is measure the actual diameter of my tires to see how close they are to calc'd. That may be the missing link.

Must be why CAIs get better mileage! If you believe that a manual spins slower because of a CAI then you shouldn't personally be doing anything mechanical to your car. The speedo wasn't changed and your tires aren't 2.5" taller(10%). Your Kuhmo diameter specs are the same as the OEMs. You can check it at Tire Rack.

I agree, unless you do a major engine or tranny replacement or modification, ur RPMs are going to stay the same regardless. The only affect that I have ever seen is when I started changing my oil myself and my idoling RPMs dropped to under the 1k mark. I installed my Cosmo CAI recently and I too am getting horrible gas mileage thanks to my lead foot