At 03:23 AM 6/5/00 -0400, you wrote:
>Can anyone describe the difference between open loop and closed loop in and
>OBD II system?
The simplest explanation is that under closed loop, the oxygen sensor is
the major component which is determining your air/fuel ratio. (The
computer reads the oxygen sensor; when the mixture is too rich, it leans it
out, then when it crosses the lean threshold, it richens it back up, and so
on.)
Under open loop, the oxygen sensor isn't used; your actual air/fuel
ratio is not being monitored. Which sensors the computer uses depends on
the type of fuel injection system, but generally, the computer is using
sensors such as MAP, TPS, ECT, etc. along with a lookup table to determine
the amount of fuel to inject. The lookup table is pre-calibrated by the
manufacturer and generally is set up to err on the rich side.
-Jon-
.--- Jon Steiger ---- jon@dakota-truck.net or stei0302@cs.fredonia.edu ---.
| Affiliations: AOPA, DoD, EAA, NMA, NRA, SPA, USUA; Rec & UL Pilot - SEL |
| '92 Ram 150 4x4 V8, '96 Dakota V8, '96 Intruder 1400, '96 FireFly 447 |
`------------------------------ http://www.cs.fredonia.edu/~stei0302/ ----'
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:51:39 EDT