Airflow Meter Swap
I have a Peugeot 405 Mi16, the 108kW 1.9L model (XU9J4Z motor) and I'm interested in using the Digital Fuel Adjuster featured in numerous AutoSpeed articles to help with a conversion from the vane type AFM to a less restrictive hot-wire MAF. I'm looking for improved throttle response and more precise metering. Not to mention the ease and low cost of replacing a MAF over the Bosch/Motronic vane type AFM.
Here's a hypothetical, please bear in mind that I've got very little practical experience with electronics and tuning. Say I've built the DFA and hand-controller, I have a hot-wire MAF from an RB20, 25 or 30 (suggestions welcome). Hot-wire does not measure intake temperature so I have to take the sensor from the original AFM and mount it in the intake. I've worked out which pins are power, earth, output. On the original AFM I've also worked out which wires are power 5V, earth, output 1-5v and intake temp (3.4v @ 20 degrees C approx).
I install the DFA on the original set-up first, disconnect the O2 sensor and with a pen and paper record voltage values at set load points. Every 250-500 rpm should be fine. I then disconnect the AFM and plug in the MAF (will use connectors so it's plug and play) and simply input the same voltage values at each load point. At this point I can let interpolation do it's thing, plug the O2 sensor back in and drive down to have everything checked with a wideband O2 sensor and dyno.
I'm yet to work out is the self-cleaning process
on the MAF though. Most use a blast of heat to burn off any contaminants upon
shutdown. I have a feeling that the one/two extra pins found on the MAFs are for
this function. Is it simply a short providing the blast of heat or something
more complex? Am I on the right track? I hope to combine this with an inlet cam
swap and equal or surpass the 160hp UK spec Mi16's.
The process that you have suggested looks largely fine. However, to avoid problems with moving the intake air temperature sensor, devising a timing circuit to trigger the self-cleaning process, and the need to extensively recalibrate the shape of the new airflow meter output curve, we suggest that instead of replacing the vane airflow meter with a hot wire, you simply fit a larger vane airflow meter. As described at Real World Air/Fuel Ratio Tuning, it is a fallacy to suggest that at full throttle, vane airflow meters are restrictive. An appropriately sized one will in fact be less restrictive than a hotwire of the same nominal cross-sectional area. A larger vane airflow meter will need much less extensive mapping by the DFA.
More on Fuel Consumption
Bravo with the Driving Emotion editorial on fuel consumption. The ideas on the issues, particularly risk, are well considered. The capital cost of the car is an issue; if the car is cheap enough to be discarded if fuel prices rise substantially, it matters less. It is also worth pointing out another recent editorial, that by Paul van Valkenberg in Racecar Engineering, where he points out that the (coming?) energy crisis is a social problem rather than a technical one. It seems to me that the world is still looking for technical solutions.
Thanks for keeping me sane with a daily dose of real car information. Working and living in the UK, your new car tests and stories help to keep in the know, when family and friends ask for input in to their car buying decisions. Loved the articles about the kit cars (Lotus, Westfield and Skelta) and cannot wait to return to warmer climates and my tools so I can built something for myself. Next time you are out in Perth you may want to check this one out - www.lfperformance.com.au.
I was reading your new brake articles New Brakes for the Falcon, Part 1 and New Brakes for the Falcon, Part 2. You didn't mention that you did any after install bedding of the brakes. I am curious, did you bed in your brakes? If so, what process did you use? If not, why not?
Fair comment. Here’s what brakes supplier RDA has to say:
When a vehicle has had both new rotors and/or just new pads fitted, there are two processes or objectives to getting the brake system to operate at optimal performance.
The first step is to make sure the disc face is clean of all oils/anti rust or any foreign matter like previous brake pad material. If the rotors are not being replaced then it is imperative that the disc is machined prior to the fitment of new pads - without exception. The second step is heating (not cooking) the brake rotor and pads, to transfer the pad material evenly onto the rotor face. This step involves performing a series of stops, so that the brake rotor and pad are heated steadily, to allow the transfer of pad material onto the brake rotor friction surface.
While performing a series of brake applications to transfer the pad material, care should be taken to not come to a complete stop, as this can lead to the transfer of pad material unevenly on the disc at the point where the pad comes to rest on the friction surface. A typical program of 8-9 brake applications, from 60 km/h down to 10 km/h, without any cool-down in between, is sufficient. For performance pad materials, a further two sequences of ten stops will be required after a cooling down period between each cycle to ensure that the pads have reached the required higher operating temperature to allow for the pad material to transfer effectively. At all times during the bedding in process, care should be taken to not apply the brakes in a harsh manner or decelerate from high speeds, as this will corrupt the transfer of materials and lead to uneven material build up on the rotor surface, which in most instances will require machining to regain a flat rotor surface for optimal operation.
How will I know if they are bedded in? The two major visual indicators are disc rotor discoloration and machining marks on the friction surface of the disc rotor. (1) Disc rotor should have a slight bluish tint with a grey tint that indicates where the brake pads have come into contact with the rotor. Too much heat will cause the rotor face to be extremely blue. (2) If there is still a shine on the rotor surface, then not enough pad material has been transferred.
Once brakes have been bedded in, it is also important to keep them that way. If any brake pad is used below its adherent operating temperature over a period of time it will slowly remove the transfer layer on the rotor surface. Standard - and especially performance pads - like to be driven a little more aggressively every now and then to maintain this pad material on the rotor friction surface. Passive use of brakes over an extended period of time will in effect lead to unbedded brakes.
Falcon Pedal Travel
The Falcon underwent a roadworthy check prior to our purchase...
The new format - Seems OK to me, but
too soon to judge. I see you are going to pay close attention to how the
articles are scored. Again, OK by me, but as soon as I scored an article I
realised I wanted to add a comment, perhaps to say why I thought it was good, or
not good, or good, but... I appreciate that pushing readers to vote is bad
enough (ie, how many readers do vote, less than 20%?), and that pushing them to
add a comment on every vote would reduce the involvement even further, BUT, I
think it might be worthwhile (ie, I would use it) if the reader was offered the
opportunity to augment or refine their vote by a text comment. "Do you want to
comment on this article? Yes or No". For example, some articles may come across
as good articles, but as I'm not really interested in the topic I'm not in a
good position to judge. So here's another opportunity for refinement, two scores
per article: How good was it?, and How relevant to you?