In Dash Air/Fuel Monitor Gauge on BMW e34

	This article is the one in a series that will be released in conjunction with Wayne's upcoming book, 101 Projects for Your BMW 3-Series. The book will be 256 pages of full color projects detailing everything from performance mods to timing the camshafts. With more than 350+ full-color glossy photos accompanying extensive step-by-step procedures, this book should be a staple in any 3-Series owner's collection. See The Official Book Website for more details. The book is due out in October 2005.
[click to enlarge] Figure 1: Voltage Curve of Lambda Sensor Figure 2: Air Fuel Mixture Curve Figure 3: Construction Schematics		Foreward from Wayne: Gabriel offers us this great tip on building an in dash air-fuel monitor. This can be potentially used to monitor your car's performance, and may also allow mixture adjustments while driving. Gabriel has just recently begun to learn English, so I have edited the text for better readability. Intoduction: The lambda sensor outputs a voltage signal that represents the instantaneous composition of the air-fuel mixture, from near 0 Volt (too lean) to 1 V ( too rich). See Figure 1. The sensor must have reached a temperature of above 350°C before it outputs a reliable signal. In my case, my Porsche 911 has 1974 headers, and I installed the O2 sensor approximately 15cm before the muffler connection. Don't install the O2 sensor too close to the exhaust valve cover, otherwise, you will have to remove the o2 sensor every time you do a valve adjusting job. A generic O2 sensor has a M18x1.5 threads, but I didn't use them. I found it more practical to measure the sensor diameter (this is measured on the electrode end, approx 10.25mm), then drill a hole with the same or smaller diameter and install it using a "pressure fit". Then, to completely constrain it I used a wire type bracket. I used (for more accuracy) a four wire (internally heated) O2 sensor. There are two signal cables (wire it to the cockpit) and two for the heating element (connect one to ground and other to +12V). In my NGK O2 sensor, the heating wires are white. You can check it with a multimeter, as the heating element has aprox. 6 ohm resistance. The other two (black & gray on mine) are the signal cables. When you have the signal wires routed near your dashboard, you can connect a generic digital voltimeter. However, as you can see in Figure 1, voltage from the O2 sensor is not a linear function; it rises quickly near lambda factor 1 (14.7:1 air/fuel) and slowly at rich & lean ends, so you have to compensate this if you wish more precise readings. I used two LM3915 units to drive 20 leds, and to compensate for the lambda curves at the same time. See Figure 3 for the schematics. PARTS: 2 LM3915 20 LEDS (RECTANGULAR, BETTER LOOK), 8 RED, 12 GREEN 2 180 OHM RESISTOR 1 22K OHM PRESET 1 4.7uF 16v capacitor 1 7805 (5v regulator) with heat sink 1 pcb The following information was obtained by me by playing with this A/F Meter. You can start with this information and practice. If you have found anything wrong or incorrect in this article, please email me. Adjusting P1: Apply 0.92 Volt (check it w/ a digital voltimeter) to the signal input and adjust P1 until led 16 just comes on. or: Turn on your engine and wait about 15 or 20 minutes to warm up the O2 sensor. If you have CIS ( K-jetronic fuel system) just apply light pressure on the sensor plate with your finger until the engine reach maxium RPM. At this point, led 16 should be on, if not, adjust P1. On carburated engines, move the idle mixture adjusting screw to obtain maxium rpm and move P1 to turn led 16 on. DRIVING WITH IT (also see Figure 2): On Idle: Values between led 6 to 15 are acceptables. You will have smoother idle around led 11. Partial throttle: Between LED 6 to 11 Full throttle: LED 16 Suggestions & questions: write to: Gabriel Pennella sarasa911@yahoo.com FEEDBACK: John Francis Duncan wrote: People who already have an o2 sensor installed in their car can use the existing o2 sensor by tapping into the signal lead. Yes, you'll have to find the correct wires. Some lambda sensora have one, two, three or four wires; it depends if it has a heating element or not. I don't know exactly what kind of o2 sensor Porsches use (I think, 1981 year onwards), but I hope that somebody can provide more info about that. John Rodgers (jrrogers@home.com) has the following hints and tips on making this Air-Fuel Monitor: 20 LEDs take a lot of room, plan accordingly for a case 4 to 5 inches x 1 to 2 inches so they can go across the face nicely. The 4.7 microfarad capacitor may not be necessary. According to National Semi-conductor it is needed if LED wires are over 6 inches in length. I left it out and it works okay. The 22kohm preset was too low in value. I ended up using a 47k preset set to full resistance. to make light 16 come on at 0.92 volts signal. Use old/wornout 1.5 volt batts to supply the signal voltage or make a variable DC power supply as I did, but it is hard to find one that goes below 1.25 volts. Adding a large pot across the signal connections will drag the signal voltage down less than 1 volt so tou can calibrate it. The long wire on the LED is the Positive side, won't work if backwards. Use 18 pin sockets to mount to the pcb and insert the ICs after all soldering is done. Use the minimum heat to solder or a heat-sink, I overheated some parts and had to redo them. Dick Lague (r.lague@worldnet.att.net) adds this additional thought: I read the tech piece on installing an oxygen sensor. I have used such a setup in my 1955 Speedster. It is a great tool for tuning. There are at least two commercially available units. K&N [the air filter people] and C.B. Performance make air/fuel Ratio meters. I used the C.B. Unit in the Speedster. It is a 2" round analog electrical gauge. It is heavily dampened and reads from 12:1 to 17:1. You can either buy it as a complete kit of the gauge only. Gauge only part#2910 Complete kit 2905 C.B. Performance 1715 N. Farmersville Road Farmersville, CA 93223 K&N makes a gauge with 10 LEDS. It is also a 2" round instrument. The part # for the complete kit, which includes the gauge, oxygen sensor and weld on sensor adapter is 85-2441. I believe it is around $100.00 The gauge is also available separately. You can find the K&N Air/Fuel Ratio monitor kit at our online store! This technical article is made possible solely through the support of Pelican Parts. If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.

RD headers on BMW e34

	Cost: $250 - $1000 Difficulty: Time: 4hours-2 people
BMW E 34 535i Racing Dynamics headers
You now know everything about exhaust and understand that there is a couple of HP to gain by installing a set of headers (more with a turbo of NOS). Let me guide you in the installation of Racing Dynamics headers in a Bmw E34. You now know everything about exhaust and understand that there is a couple of HP to gain by installing a set of headers. And you really feel them (more with a turbo of NOS). Let me guide you in the installation of Racing Dynamics headers in a Bmw E34.
Coating procedure:
You can send your headers to a coating shop to have them coated inside and out. The cost will be around $300 - $450. Or you can buy black satin that will reduce the heat radiated by the headers. (They have more surface than the original manifolds and generate a lot of heat. And you want to keep the head down in the engine compartment and near the A/C lines). I Sand them with 200 grid sand paper then cleaned them and had them coated at my favorite bodyshop. The only problem is that before they are cured on the car, they are a little bit sticky.
Procedure
• Welding equipment (MIG) or an exhaust shop. • Pipe enlarger or (much better as this is thick stainless) get a muffler shop to flange the RD tubes, exactly to fit it's diameter. • 13mm socket and close end wrench. • 4 x M8x55 (or M8x60) bolts and M8 nuts. • 2 New exhaust manifold gaskets and the two catalytic conv. gaskets (2 different sizes). • 12 new exhaust bolts (cooper ones) depending on the shape of yours.

1- Lift the front and back of the car and put it on jack stands (a lift will be perfect). You will have more space to work underneath. Spray a lot of WD 40 on the exhaust manifold bolts and catalytic converter junction bolts.
2. Disconnect the O2 sensor and remove the protective rail (2x 10mm bolts) if equipped. 3. Don't remove the exhaust manifold now. Remove the bolts out of the junction between the catalytic converter and the resonator. They might be completely rusted, in this case use a hacksaw and cut the bolts out.
	4. Remove the connection between the back of the catalytic converter and the resonator (4x13mm bolts... at least they were when the car was new). If the bolts are too rusty, cut them with a saw as you won't reuse them. Clean all the rust from the holes to be able to fit the new screws.
5. Disconnect the connection between the two exhaust tubes and the exhaust manifold. Cut them if the bolts are too rusty as you will not reuse them again. 6. Remove the 12 bolts out of the old exhaust manifold. Don't worry if you remove the studs with the bolts, studs can be purchased in any auto store. If you break one... that's another story. (I broke one but I was removing the cylinder head) 7. Remove the old exhaust manifolds. You can sell them on ebay for around $0.50ea.
8. Time to remove the catalytic converter. Place a big cardboard box or something to hold the catalytic converter, you DON'T want to drop it as it is fragile. Remove the connection between the front of the catalytic converter and the frame (depending on the model). (The connection is different between automatic and 5 speed).
9. Make sure there is something or someone to hold the catalytic conv. Pull on it to disconnect it from the resonator then take it out. You can now remove the O2 sensor with an O2 sensor socket.
	10. Time to cut the catalytic converter tubes to fit the RD header tubes. Don't follow this picture, the small tube is placed on top and the longer one on the bottom. You want to (as on the picture) place the RD tube (the black one on the the pic) next to the catalytic converter tube, both lining up at the angle (red line). Cut 1cm (1/3") before the RD tube flange. (Green line). Repeat the same with the other tube.
11. Now the fun part. Install both headers on the car. Follow the top pictures to see which one is the right and the left one. (It is a little bit tricky to install the left one, but you will figure it out). Install new bolts if yours look rusted. Don't forget to install the headers' gasket. Isn't my engine clean? I should say: Gordon's clean.
12. Slide the RD tubes into the cat tubes, install the O2 sensor back into the cat. Slide the cat back under the car and with some help, install it back. Install the bolt connecting the cat. to the frame. Install the 4 bolts connecting the RD headers to the RD tubes. Don't tighten the tubes bolts too much. Install the O2 sensor rail back and connect the O2 sensor plug. If you coated your headers with black satin, let the car run for 30min at least the hood open. The heat from the headers will cure the coat. Don't worry if smoke is coming out of the engine compartment.

Caliper Painting on BMW e34

Here's a rough guide to painting your calipers.

Of course you can buy special caliper paint, but over 5 cars I've used Japlac High Gloss Laquer, Colour - Jet Black (of course) and never had any problems with heat. Another good paint would be a gloss enamel, but I have the Japlac, so...

For those of you thinking to paint them Silver, I would think again! I've never found a silver paint that has the same smooth enamel type finish, they all have a graininess to the finish which holds brake dust. A very smooth glossy finish keepsl the calipers very clean, since every time you wash the wheels, the calipers get cleaned too.

On with the instructions...

Unsurprisingly, this is another wheel off job, so jack up the car, remove the wheel and make sure the car is also supported by an axle stand - you don't want it falling off the jack and damaging the brake disk!

Depending on how dirty your caliper is, you might want to begin by lightly cleaning the caliper with a wire brush to remove any brake dust or corrosion already there.

You don't need to bother priming the surface - usually a single coat of paint is enough to last a couple of years. I find it easiest to apply the paint using a 1/2" paint brush - it's big enough so that it doesn't take all day, and small enough that it's easy to control exactly where the paint goes. Using a paint with a good glossy finish will ensure that you don't see any brush lines as the paint will set to a smooth finish.

When painting the caliper, there isn't really much to go wrong. Make sure you keep the paint away from the actual brake pads, and watch for the places where the pads sit, you don't want to restrict their movement as they wear down. Don't be paranoid - just be careful!!

It's also ok, to paint the little shield on the front one, and the springy tensioner thing.

Make sure and get a nice even finish, and use the opportunity you have with the wheel off to give the inside of the alloy a good clean!

You can remount the wheel while the paint is drying, just be sure to leave the car sitting for a few hours while the paint hardens. (Hard I know! )

Once you've done all four wheels you can stand back and admire your work!