Page 1 of 1
air flow meter resistance too high?
Posted: Fri Aug 11, 2006 1:40 pm
by richcarl32
have a 78 bay FI , i was checking the air flow meter resistance between terminals 6 and 9, the resistance is 314 ohms. according to the bentley is is above the range is should be but not by much, only 14 ohms. should i do as the bentley says or is 14 ohms not much to worry about. also what are the advantages of the resistance between the terminals being on the lower end of their acceptable ranges vs the top of the range?
Posted: Fri Aug 11, 2006 3:23 pm
by raygreenwood
In general you do not want to be to far above or below nominal resistance. In certain resistance based systems....resistance affects speed or time of a calculation. In the case of a resistance based temeperature sensor....it affects the value based upon temperature. If its too high or low...you may get more or less fuel than a given air or head temperature really needs. You get poor running.
Off the top of my head I cannot remember what those particular terminals were hooked to within the AFM. If they are hooked to the wiper arms ...the resistance could be significant. Iwould bet though....That the difference may be affected by a proper cleaning of teh contacts and terminals. I will look in teh books and see what these affect. Ray
Posted: Sat Aug 19, 2006 1:13 pm
by Piledriver
In the lower resistance ranges, most VOMS are pretty inaccurate, and remember, the typical spec on a 300 ohm variable resistor would be ~10%, which would be +/- 30 ohms... (usually better, but)
Unless you are using a decent meter (>Fluke 77 ish), don't completely trust it, and even then, electronic parts have range specs.