Wednesday, March 6, 2013

It begins!

..slowly

I've mostly worked out everything that needs to be done for the engine swap. How to route the radiator hoses is the trickiest problem so far.

The most exciting part is finding a MAF sensor that I can use. http://en.wikipedia.org/wiki/Mass_flow_sensor#Hot_wire_sensor_.28MAF.29 I've taken it from a '96 Ford Laser. The same sensor is also fitted to Mazda MPVs. Since they have a bigger 2.5L V6 engine, I expect the sensor to cope well with large air volumes.

Test wiring was a little scary since the wiring diagrams I found aren't 100% clear on what wire does what. Don't want to break it! I guess it's because it's aimed at diagnostics and repair. For instance it shows/says things like "terminal 1A should be 2v" or "check for continuity between x and y". Following the diagram lines doesn't give much more information. Without knowing for sure what terminals were pull-up or pull-down and what voltages they worked at, the best i could do was take an educated guess. To be safe I started by feeding small voltages through various terminals and probing the others at the same time. Keeping an eye on any sudden current dips/ spikes or burning smells/ magic smoke/ audible pops may or may not have helped avoid damage. They're more like "You broke it", than early warning signs.

I'd check to see if blowing through the sensor would cause any measurable change in voltage on the wire that was being probed. Eventually I found the right combination for the hot wire. The response was initially very slow, but became faster after blasting it with a leaf blower. I guess the dirt added some thermal mass? Or maybe it was acting like an insulator?

Either way, an ADC working on the right voltage range should be all I need to read the signal :) Now, does anyone have any suggestions on how to properly clean a MAF sensor?