AFR Measurements and the early 911

[dicklague]

I started a post here a few months ago asking for advice on AFR measurement devices. It was time for me to set up my MFI right, and I was emboldened by all the MFI reading I had done on this forum.

I wanted to learn more about the Innovate product, and I was also interested in the Daytona Sensors Wego IV which seemed to be a state of the art compact unit. No one seemed to have used the Wego, and I did get feedback on the Innovate.

I continued Googling AFR and learning all I could. Finally I sprung for the Wego IV and have really been impressed with it. I installed it permanently in my 911 and have made great progress with the MFI.

I hesitated to post some follow up reports here on the Daytona Sensors Wego IV because our host sells the Innovate and PP is such a great resource that I did not want to get sideways with anyone.

I became so passionate about the Daytona Sensors AFR instruments that I decided to get involved in the distribution. I contacted Scott at Pelican Parts after meeting with them, and he and Wayne saw the merit in the product and are now stocking the Daytona Sensors line of AFR instruments.

I would like to share my experience with other Pelicans that are looking for a great , cost effective solution to getting reliable AFR data. I know that the MFI, carb, Turbo and early fuel injection crowd can benefit greatly from knowing what is going on with the mixture in their 911s in real time and be able to store the data for later analysis.

I have learned a lot, but of course I am still learning. So if you guys don't mind I would like to share what I have learned so far and hopefully spark a discussion here that will help us all make our 911s run better.

[dicklague]

What is the Daytona Sensors Wego IV? Well, basically it is a control unit, readout and data logger for the Bosch LM 4.2 wide band oxygen sensor. This newest generation of O2 sensor is very accurate and sensitive. These sensors are expensive $100 or so and have a 5 wire harness.

That also has a digital readout for AFR, 2 hours or more of data logging, a USB connector on the front to download data and configure the unit. The Wego is sold as a complete kit that includes the main unit, the wide band O2 sensor, wiring harness, a weld in bung for your exhaust system, software CD, installation instructions. The complete kit retails for $440. For a Porsche permanent installation the 12 foot extension cable is a good idea for a permanent installation. The supplied cable is fine for a front engine installation, but a bit short for a rear engine or one where the O2 sensor is at the rear of the vehicle.




Here is how it works. When you first turn on the unit you need to free air calibrate the unit. The best way to do this is to have the O2 sensor not inserted in the exhaust system. Turn on the unit. First thing you see is CL in the bright blue LED. This means the O2 sensor is cold and the electric heating element is warming up the sensor. Once the light goes out you should get the highest AFR reading of 19.5. There is a small adjusting screw in the upper left of the front panel. Turn it clock wise until the readout says FA [free air] then turn it back slightly until you see 19.5. the perfect adjustment is when it flashes from FA to 19.5. It is recommended that you adjust the calibration occasionally to compensate for aging of the sensor.

The Wego IV records data whenever it is in operation. It records 8000 seconds of data and adds the new data to the end of the file. So the whole time you are driving the Wego is recording time, AFR, RPM. There is also one more analog voltage input of 1-5 volts DC. This could be a manifold pressure/vacuum sensor, a throttle position sensor, temperature sensor or other sensors. The software allows you to calibrate the input to inches of mercury, % of throttle etc..


A dual unit with 2 sensors and 2 readouts is also available. This allows measuring each bank individually.



The instructions are quite complete and comprehensive. Go to Daytona Sensors LLC - Engine Controls and Instrumentation Systems for Automotive and Motorcycle Applications if you want to download a .pdf copy. You can also dowload the software and take a look at it.

What I really love about this unit is that everything that you need is in the kit. Once your have the bung welded into the exhaust the rest of the installation consists of hooking up switched 12 VDC to power the unit and running a wire to the back of your Tachometer for the RPM input, and hooking up the 5 wires from the sensor to the connector in the back of the unit. No RPM adapter needed. One small 4" x 3" x 1" unit to install under the dash or somewhere up front. And you are in business.

[dicklague]

Here is how it works. When you first turn on the unit you need to free air calibrate the unit. The best way to do this is to have the O2 sensor not inserted in the exhaust system. Turn on the unit. First thing you see is CL in the bright blue LED. This means the O2 sensor is cold and the electric heating element is warming up the sensor. Once the light goes out you should get the highest AFR reading of 19.5. There is a small adjusting screw in the upper left of the front panel. Turn it clock wise until the readout says FA [free air] then turn it back slightly until you see 19.5. the perfect adjustment is when it flashes from FA to 19.5. It is recommended that you adjust the calibration occasionally to compensate for aging of the sensor.

The Wego IV records data whenever it is in operation. It records 8000 seconds of data and adds the new data to the end of the file. So the whole time you are driving the Wego is recording time, AFR, RPM. There is also one more analog voltage input of 1-5 volts DC. This could be a manifold pressure/vacuum sensor, a throttle position sensor, temperature sensor or other sensors. The software allows you to calibrate the input to inches of mercury, % of throttle etc..

[dicklague]

here is a better photo of the dual unit. Basically the same as the single but with 2 readouts, sensors, and data logging both sensors.



These is the dual unit with the labeling for the rear connector:

[dicklague]

Not much feedback here, but I am going to press on with a quick install over view Maybe that will answer a few questions that people have.

Basically the install is pretty straightforward. The biggest job can be getting the O2 sensor installed. I will post some photos of installing the bung in the exhaust system and some advice on where to put it.

A temporary installation is also possible. There is an Innovate adapter that is basically a tailpipe stiffer that you screw the Bosch wideband sensor into. You can also build a tail pipe sensor pretty easily. I will post some photos of the one I built.

[dicklague]

For a temporary installation, you can easily build a tailpipe sniffer.
It is constructed from a 6” length of 1” ID steel pipe. A 3/4” hole is drilled approximately 2” from the end and an 18 x 1.5 mm weld nut is
welded onto the pipe. After welding, an 18mm x 1.5 tap is used to clean the threads.

Fresh air flowing in from the end of the pipe is a problem on these installations, so a small piece of steel 1" wide is bent at 90 degrees to let air flow out, but restrict air coming back in.



A couple of hose clamps hold it on the pipe and hold the deflector in place. Does not look too elegant, but it does work.

Here is the cast aluminum Innovate sniffer. You screw the O2 sensor in the end of this one and the thumbscrew holds it in place.



I have not tried this one, but I know Dave at TRE Motorsports has used this sniffer with the Wego IV.

My personal experience is to be very cautious about trusting the idle AFR with this setup. Does not matter what electronics you are using, get off the throttle and at Speed air will rush up the tailpipe and dilute the exhaust. the rest of the range seems to be OK.

The best way to install is to either mount the o2 sensor(s) at the junction of the 2 banks, or install 2 sensors just after the header junction.

With 2 O2 sensors you will need the dual Wego unit, or just monitor one at time with the single unit.

[GrantG]

I've got one of these and it's been a great tool to tune my MFI mixture:

MoTeC > PLM > Overview

[dicklague]

The PLM seems to be a nice setup.

I am happy to find someone that has one, I have a couple of questions about the PLM.

Does it do data logging on its own?

Does it have RPM input and allow you chart RPM AFR?

Also what is the cost of the kit?

[GrantG]

Hi - If you download the manual from this link, it should answer your questions:

http://www.motec.com./plm/plmdownload/

I have never used it for data logging (don't know if it requires additional accessories or not to do that). However, I have found that it is very easy to set the mixture on MFI with the PLM and can't imagine that it would be any more accurate or faster to do so with charting or data logging.

The display reacts very quickly (several times per second - I think 10Hz), so it is very easy to see what it's doing when driving. I just aim for a Lambda of 0.9 to 0.92 at high revs (around 6,500rpm) under load and full throttle.

My motor tends to richen a bit more than that as it approaches 7k.

It is also easy to set idle mixture (0.98 or so at warm idle around 850rpm).

You can set it in an hour or two pretty easily and then monitor it thereafter to be sure it's not too fat nor too lean in a variety of circumstances. You can also watch how the AFM changes with throttle position at a given speed. It can help you get the most from the car at part throttle and lower revs (see how it gets too rich if you give too much throttle at low revs - you can see and feel an improvement if you roll onto the throttle in those situations).

Take your MFI tools (pelican sells long screwdriver, idle adjuster, and long Allen key) with you to the track or on an uncrowded trip and you'll be set.

I don't recall the price, but it's not cheap.

[dicklague]

Installation of the wide band O2 sensor in the exhaust system pretty much means removing the muffler, Drilling a 3/4" hole for the O2 bung and welding the bung in place.

I have a Bursch exhaust on my 911 the has 3 small tubular mufflers that are glasspacks.......well there was fiberglass in there at one time.

I decided that I would try different locations for the bung and experiment a bit. The kit comes with a bung that measures 18mm with 1.5 mm thread. The same as an 18mm spark plug. This is the size of the majority of oxygen sensors. I searched around eBay and found someone in NV selling 10 bungs and 10 plugs for $20 or so, and used this in this experiment.

I removed the exhaust and drilled a 3/4 in hole for the bung



I am not sure if I will ever use them all, but at least I don't have to take the exhaust off again to try a different location. Unused bung have a plug screwed in.

here is the bung before welding:




Tack weld the bungs in place and then finish weld. When done, run a 18mm X 1.5 tap through the bung to be sure the threads are good and not distorted or welded over. A spark plug thread chaser should also do the job.

I put a bung at the junction of the 2 pipes and one close to each flange.




this shot from below shows the sensor at the merged portion. on the right in the photo is the back of the RS bumper. Those bolts are for the license plate bracket. The wire goes up through the rubber gasket into the engine compartment.

[dicklague]

Originally Posted by GrantG

Hi - If you download the manual from this link, it should answer your questions:

MoTeC > PLM > Download

I have never used it for data logging (don't know if it requires additional accessories or not to do that). However, I have found that it is very easy to set the mixture on MFI with the PLM and can't imagine that it would be any more accurate or faster to do so with charting or data logging.

The display reacts very quickly (several times per second - I think 10Hz), so it is very easy to see what it's doing when driving. I just aim for a Lambda of 0.9 to 0.92 at high revs (around 6,500rpm) under load and full throttle.

My motor tends to richen a bit more than that as it approaches 7k.

It is also easy to set idle mixture (0.98 or so at warm idle around 850rpm).

You can set it in an hour or two pretty easily and then monitor it thereafter to be sure it's not too fat nor too lean in a variety of circumstances. You can also watch how the AFM changes with throttle position at a given speed. It can help you get the most from the car at part throttle and lower revs (see how it gets too rich if you give too much throttle at low revs - you can see and feel an improvement if you roll onto the throttle in those situations).

Take your MFI tools (pelican sells long screwdriver, idle adjuster, and long Allen key) with you to the track or on an uncrowded trip and you'll be set.

I don't recall the price, but it's not cheap.

Interesting. I sounds like it has worked well for you. I am finding the same thing. As I mentioned, I am really getting on top of my AFR setting in the MFI. I carry the MFI tools with me in my tool bag in the trunk.

The digital read out works well, but I really love the data logging feature. Allows me to match RPM, AFR, MAP and see what is going on over and extended period and adjust accordingly.

I am considering adding cylinder head temp so I can reference what happens when the engine gets really warm.

Thanks for the input. I just downloaded the PLM .pdf and I am reading it tonight.

[tobluforu]

Originally Posted by dicklague

For a temporary installation, you can easily build a tailpipe sniffer.
It is constructed from a 6” length of 1” ID steel pipe. A 3/4” hole is drilled approximately 2” from the end and an 18 x 1.5 mm weld nut is
welded onto the pipe. After welding, an 18mm x 1.5 tap is used to clean the threads.

Fresh air flowing in from the end of the pipe is a problem on these installations, so a small piece of steel 1" wide is bent at 90 degrees to let air flow out, but restrict air coming back in.



A couple of hose clamps hold it on the pipe and hold the deflector in place. Does not look too elegant, but it does work.

Here is the cast aluminum Innovate sniffer. You screw the O2 sensor in the end of this one and the thumbscrew holds it in place.



I have not tried this one, but I know Dave at TRE Motorsports has used this sniffer with the Wego IV.

My personal experience is to be very cautious about trusting the idle AFR with this setup. Does not matter what electronics you are using, get off the throttle and at Speed air will rush up the tailpipe and dilute the exhaust. the rest of the range seems to be OK.

The best way to install is to either mount the o2 sensor(s) at the junction of the 2 banks, or install 2 sensors just after the header junction.

With 2 O2 sensors you will need the dual Wego unit, or just monitor one at time with the single unit.

I have the tail sniffer (a bung is better), but since you tune pretty much at WOT/cruising and idling for a MFI, I find it works ok, but the rpm attachment is needed as well.

[tobluforu]

Originally Posted by dicklague

Interesting. I sounds like it has worked well for you. I am finding the same thing. As I mentioned, I am really getting on top of my AFR setting in the MFI. I carry the MFI tools with me in my tool bag in the trunk.

The digital read out works well, but I really love the data logging feature. Allows me to match RPM, AFR, MAP and see what is going on over and extended period and adjust accordingly.

I am considering adding cylinder head temp so I can reference what happens when the engine gets really warm.

Thanks for the input. I just downloaded the PLM .pdf and I am reading it tonight.

MAP, how do you log that on a MFI car, did you add this sensor?

[dicklague]

Yes, I added a MAP sensor. it is pretty easy to do. I used a GM MAP sensor. These are very available and come in 3 varieties, 1 BAR, 2 Bar and 3Bar. The 2 and 3 are for use with turbos.

The map sensor is connected to the vacuum advance line to the distributor. You also need a 5 vdc regulated power supply which is one voltage regulator and a couple of capacitors.,


Here is the connection to the vacuum line. I just used a small T.



Here is what the MAP sensor looks like. The silver box is the power supply. It converts 12vdc to regulated 5 vdc. This is necessary, because MAP needs 5vdc to be fed into the sensor. The signal then runs through a piezo mechanism which acts as a resistor and modifies the voltage according to vacuum, and gives you an output voltage from .3 to 4.8 or so DC. Other sensors like throttle position and temperature sensors use this 5 volt source.



You can see the vacuum line going into the sensor. The brown weatherpack connector is visible on the black MAP sensor.

The Wego IV changes the voltage input into a reading of inches of mercury [inHG] and then displays it on a graph. You can also download it in a spreadsheet. I will post some examples.

[dicklague]

Here is a screen grab shot of the MAP readings vs. AFR. Map in inHG scale is on the left side. AFR on right. Green line is AFR and the red line is vacuum.




The data can also be downloaded to a spread sheet. Below is an Excel spread sheet screen grab of a section of an AFR test run recorded to the Wevo data log file. These log files can be over 2 hours of running. On the left is the time in seconds, next is the AFR ratio, next is RPM. The last column on the right says inHG, but it is actually MAP voltage. The higher the voltage the more load on the engine. This can be converted into inHG by using a simple calculation in the spreadsheet. I have done this in other spread sheets.



I find the spread sheet data a great way to study what is going on with the MFI at various conditions.

[dicklague]

I have been doing a bit more research on the MoTec PLM (professional lamda meter). It is a very interesting unit that reads in lamda or AFR. I can't see any evidence that it includes data acquisition and download. You can upload settings to the unit through an old fashioned RS232 serial port and not a USB. If you have a newer laptop you will need a serial to USB converter and software. There are 2 user programmable digital inputs such as RPM.

The readout is packaged in a nice aluminum case.



The only prices I could find for the kit in the USA were all in the $1600 USD range.

[dicklague]

Here is a photo of the PLM




I seems that you need a MoTec data collection system to record AFR and other fuel mixture data like RPM MAP etc..

[TimT]

We probably have a dozen wide band units in the shop. The Motec was one of the first we used.. One reason we dont use the MoTec any more is the sensor is very expensive. The PLM we have uses a Uego sensor which costs around $200. The newer generation of wide bands use the Bosch LSU series of sensors which are less expensive.. (around $65?)

Back to back testing of less expensive systems vs the MoTec found the differences in results to be almost nil.

[dicklague]

Thanks for the input on the PLM. I noticed that the docs and literature all went back to 2005, which is maybe a bit long in the tooth in this technological generation.

You are right, the Bosch LM 4.2 has sort of become the standard.

What other AFR instruments do you use and how do you rank them?

[calling911]

Originally Posted by dicklague

Thanks for the input on the PLM. I noticed that the docs and literature all went back to 2005, which is maybe a bit long in the tooth in this technological generation.

You are right, the Bosch LM 4.2 has sort of become the standard.

What other AFR instruments do you use and how do you rank them?

The only AFR instrument you need is a multimeter.