» Site Navigation | | » Recent Threads | | 1999 M3 Swap 09-07-2023 10:10 PM 05-02-2024 08:18 PM 6 Replies, 403,654 Views | | | | | | 06-23-2005, 06:03 PM | #1 | Junior Member Join Date: Feb 2004 Location: Georgia Posts: 13 | Fogging Your Airbox (1998 318ti) I just wanted to give a small walkthrough to the folks who have thought about fogging your airbox and havent quite gotten to that point because of any particular reason. The following modification was done on my 1998 1.9L 318ti. But before we get started, here's some info that you need to know about your cars intake and fuel injection system Quote: The fuel injection in the Z3s is a mass air fuel metering system. What this means is your car directly measures the weight of the air being draw into your engine and injects an appropriate weight of fuel (in the ratio of 14.7 parts air to each part of fuel) which it then ignites through your ignition system. Under cruising conditions and light acceleration your cars computer (DME) uses feedback from the oxygen (O2) sensors to fine tune the mixture. The DME measures the weight of the air using a sensor called the Hot Film Meter. (HFM) The HFM is basically a film through which a current is passed to heat it. If you were to look at the inside of your HFM you will see that the film is very small and it actually only samples a small fraction of the air that passes through the meter. By measuring the temperature change of the film (and knowing the intake air temperature) the DME is able to calculate the mass (weight) of air that is flowing over the film. It can then calculate the total mass of air flowing through the HFM. This works if the airflow through the meter is smooth and evenly distributed, in other words laminar flow. The DME then uses this to determine how much fuel needs to be injected to keep the AFR at 14.7/1, also called Lambda=1. An AFR of 14.7/1 results in the most complete combustion of your fuel which gives you the least emissions. If an engine is running rich OR lean (more or less fuel to air) the engines emissions will increase. At full throttle the DME runs the engine richer for more power. Now a key point... if you increase the airflow into your engine, the DME will measure it using the HFM (assuming smooth airflow) and will increase the fuel injected to compensate. The DME must do this or your engine would run leaner which would increase emissions. If you increase the amount of air, to keep the ratio between air and fuel at 14.7/1, the DME must add more fuel. If you increase airflow and burn more fuel you have increased your power output. ---Shawn Fogg (www.logun.org/fog.htm) | First, just take a look at your airbox and start thinking about all the things you need to take off to get the airbox out and by itself. In this picture... #1 and #2 are where two nuts are that you have to take off. #3 is something you may have to wrench out to get in to get to #2. Image #1 After I opened my airbox, I noticed some kind of baffling material that seemed to be either heat dampening material or sound dampening material. I dont know what the case may be in your car, but in mine it seemed to have "rotted" out. So i took all that out. Only the part above the air filter was ok. Take a look at this picture. Image #2 And this is my airbox with all that stuff taken out. Image #3 Ok, so once your airbox is out. You need to think about positioning for the tubing that will run from the air duct that leads to the driver side tire (or brakes). When I was doing this i saw that there was a horn in my way. So i relocated it. See these photos. Image #4 Image #5 Image #6 Ok, next is to locate the air duct that is behind the grille to the left of your driver side fog light or fog light cover. You can get to it and take it out if you take off some protective plastic peices underneath the front of the car. Make sure you disconnect the sensor on it before you go yanking away. Here is a pic. Image #7 Now you will have to cut a hole in it. I used 90 degree angled peice of PVC pipe that you can find at any hardware store. I also painted it black. Take a look. Image #8 Now take the tubing you bought (3-4 inch dryer duct tubing, or anything that works for you). Yeah take that tubing and put a tightening clamp on it, then place the air duct back into place. Be sure to pull the tubing through like in this picture, but, keep in my that the airbox should be completely out at this point so you have a lot of space to work with. Image #9 Ok. Now comes the modification on the actual airbox itself. You need to cut a hole in it and add another corner PVC peice to connect to the tube. In this picture the #2 hole is the factory hole that was there when you took the box out. The #1 hole is the PVC peice. Image #10 After that, cut your tubing to the right length, clamp on both ends, put every sensor, cap, plastic peice back on and then you're done. Image #11 Image #12 Image #13 Image #14 After I fogged my airbox i could feel a great deal of difference in the way the car drove. There is no longer that "plateau" or power. The power is constantly there to the redline. Its great, and i suggest anyone doing this performance mod. Thanks. -Sean H. ***THINGS TO KEEP IN MIND*** There are risks in doing this modification. Getting too much moisture in the engine could cause hydrolock. Also be sure to connect every sensor back where you took it off. | | | 06-23-2005, 06:38 PM | #2 | Senior Member Join Date: Aug 2003 Location: cary, nc Posts: 2,259 | that was a pretty good tutorial! i know i did mine a little differently (didnt actually connect it to the brake duct, just had it down by the foglight), but i like the tutorial...lots of pictures make it easy to follow! __________________ 1995 318ti Active Pioneer Speakers [] Aluminum Billet door locks [] ACS Pedals/Deadrest [] ACS Shift Knob / E-Brake Handle [] Clear Corners/Tails/Sides [] Sylvania Exterior Lighting [] Custom CAI [] Dinan Engine Chip [] Dinan Transmission Chip [] H&R Race Springs [] Tokico Illumina Shocks [] BMW X-Brace [] Relocated Lighter Mod [] Custom iPod Mod http://www.cardomain.com/id/robcarync | | | 06-23-2005, 07:35 PM | #3 | TRETEN IRGENDEINES ESELS Join Date: Aug 2004 Location: Rhode Island Posts: 3,687 | Yes very nicely done,it looks somple with all the pictures. Only thing i didn't like is that he is a Yankees fan.. __________________ 98 Avus Blue 318 ti Active clear outs all around,stealth turning signals,blue led interior lights, 35% tinted windows,K&N air filter, 12" Kenwood Sub, MTX Thunder Amp,Alpine cd changer, Leatherz Armrest,ACS Pedals/Handbrake/FloorMats & Vitesse Tuning Carbon Fiber B-Pillars/CF Spark Plug Cover, New 16" MSW Typer 14 Rims on Goodyear Triple Treds www.myspace.com/avusblueti | | | 06-23-2005, 07:37 PM | #4 | Senior Member Join Date: May 2005 Location: NW of Chicago Posts: 111 | Yeah, that's a very nice write up! I will do this mod in a couple of weeks. You posted the tutorial in perfect timing. Thanks! | | | 06-24-2005, 01:16 AM | #5 | Senior Member Join Date: Aug 2003 Location: cary, nc Posts: 2,259 | i noticed you cut the whole in the airbox on a different side... did you use anything to plug up the stock hole so it only sucks air from the new hole, or does it suck air from both? and i like the idea of using PVC pipe for connectors....very nice! i found that the originial tutorial for the 'fogged' airbox was a bit vague and didnt have too many pictures...i was able to get it done...but i had to really read into what they were saying... this tutorial is REALLY nice, pictures every step of the way! i like! __________________ 1995 318ti Active Pioneer Speakers [] Aluminum Billet door locks [] ACS Pedals/Deadrest [] ACS Shift Knob / E-Brake Handle [] Clear Corners/Tails/Sides [] Sylvania Exterior Lighting [] Custom CAI [] Dinan Engine Chip [] Dinan Transmission Chip [] H&R Race Springs [] Tokico Illumina Shocks [] BMW X-Brace [] Relocated Lighter Mod [] Custom iPod Mod http://www.cardomain.com/id/robcarync | | | 06-25-2005, 02:58 AM | #6 | Junior Member Join Date: Feb 2004 Location: Georgia Posts: 13 | Yes, i reconnected everything back to stock, which means i have 2 holes in my air box. It can breathe from the stock inlet also the new one. I haven't driven in the rain yet and i'm a little nervous about hydro lock. If one of the guys on this forum that has a little experience in hydro lock and how easily it can happen, would you please post a response. Thank. Oh by the way, i can feel a great amount of difference when i drive my 318ti now. I don't exactly get the gas milage i was getting before the mod. lol. (due to me constantly testing out the new feel) | | | 06-27-2005, 06:50 AM | #7 | Senior Member Join Date: Aug 2003 Location: cary, nc Posts: 2,259 | i am no authority on hydro lock, but i would guess that with two intake pipes, your fogged pipe wont have enough suction to really suck up enough water to cause problems...even if the fogged hose was submerged in water, it would still just suck air from the stock hose to releive the pressure...and if both hoses are submerged...then you must have driven into a lake but even so...not submerged...id guess that neither hose has enough suction to really take in enough water to cause trouble but then again, i am no authority on hydro lock....someone correct me if im wrong __________________ 1995 318ti Active Pioneer Speakers [] Aluminum Billet door locks [] ACS Pedals/Deadrest [] ACS Shift Knob / E-Brake Handle [] Clear Corners/Tails/Sides [] Sylvania Exterior Lighting [] Custom CAI [] Dinan Engine Chip [] Dinan Transmission Chip [] H&R Race Springs [] Tokico Illumina Shocks [] BMW X-Brace [] Relocated Lighter Mod [] Custom iPod Mod http://www.cardomain.com/id/robcarync | | | 06-27-2005, 03:42 PM | #8 | TRETEN IRGENDEINES ESELS Join Date: Aug 2004 Location: Rhode Island Posts: 3,687 | With two tubes at 2 different heights aren't you gonna get cold air and warm air going into ur engine? With one pipe there would be more suction which means more air to go in. __________________ 98 Avus Blue 318 ti Active clear outs all around,stealth turning signals,blue led interior lights, 35% tinted windows,K&N air filter, 12" Kenwood Sub, MTX Thunder Amp,Alpine cd changer, Leatherz Armrest,ACS Pedals/Handbrake/FloorMats & Vitesse Tuning Carbon Fiber B-Pillars/CF Spark Plug Cover, New 16" MSW Typer 14 Rims on Goodyear Triple Treds www.myspace.com/avusblueti | | | 07-06-2005, 04:34 AM | #9 | Senior Member Join Date: Dec 2004 Location: Lake George, NY Posts: 338 | damn looks like the pictures are down was gonna use that as my guide too | | | 07-06-2005, 04:39 AM | #10 | Senior Member Join Date: Apr 2005 Location: tailgating your slow ass Posts: 518 | Very nice job. It is very well detailed and the pictures demonstrate all of the things that you need to understand. Very nice tutorial. | | | 07-06-2005, 05:10 AM | #11 | Senior Member Join Date: Mar 2005 Location: madison, WI Posts: 402 | correct me if Im wrong but if you are going through all the trouble to fog the airbox why doesnt everyone just get a couple inches of 3' pipe, clamps and a cone filter and just make a full blown CAI. its less restrictive and has a way better sound. __________________ Mods: clear turn signals, Silverstar headlight bulbs, k&N custom CAI, removed A/C, lightened crank pulley, painted brakes, custom clutch stop, custom strut bar, x-brace, custom solid tranny mounts, Memphis sound system, Sachs sport clutch, B&M short shifter, lightened flywheel, redline MTL .... Emberrassing honda owners one drive at a time http://members.cardomain.com/mghockey | | | 07-06-2005, 06:04 AM | #12 | Senior Member Join Date: Apr 2005 Location: tailgating your slow ass Posts: 518 | actually i think that by fogging your aibox it makes more power than most of the the cai. I remember seeing a comparison on it a while back ill try to find it | | | 07-06-2005, 04:43 PM | #13 | Member Join Date: Jul 2003 Location: San Antonio, Texas Posts: 62 | What happened to the photos? Sweeet write up... and simple. I want to do this mod but the pictures aren't working. __________________ '96 Active, Boston Green Future mods:Front lipspoiler, cold air intake by Otto Racing, Hartge Rear Wing spoiler, Smoke Grey Birdseye maple wood trim kit. | | | 07-06-2005, 05:09 PM | #14 | Senior Member Join Date: May 2005 Location: Pismo Beach, CA Posts: 500 | Not to sound dumb or like a newbie, but what the hell is fogging an airbox __________________ Joe, In San Luis Obispo E30-> '96 TI sport -> E30 -> '96 TI | | | 07-06-2005, 07:34 PM | #15 | Senior Member Join Date: Dec 2004 Location: Lake George, NY Posts: 338 | | | | | | Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | | Posting Rules | You may not post new threads You may not post replies You may not post attachments You may not edit your posts HTML code is Off | | | |