Hello and a question

[Huw Scourfield]

Is there a throttle position switch fitted somewhere ?(could be on/behind
the bulkhead as on my rover 220 even). If you solve the idle problem very
likely the ecu will run closed loop with the engine held at high revs.
    Huw
----- Original Message -----
From: Peter Vieth <fitek at ix.netcom.com>
To: <diy_efi at diy-efi.org>
Sent: 17 September 2001 21:25
Subject: Hello and a question


> Hello everyone... my name is Peter Vieth and I'm a 3rd year Computer
> Science and Engineering student at UC Davis.  I have a 1986 Acura Legend
> 2.5L that has had constant fuel problems since I got it in February.
About
> a month ago I finally got all the mechanical issues ironed out and went
> ahead on tackling the Honda PGM-FI (programmed fuel injection) ECU.  I
> didn't have much luck until I came across several Rover websites and
> diy-efi.org.  Since then I've been observing the workings of the ECU and
> have some good information that I hope to post at a later date...
>
> I have run into one problem that I could use some help with.  I keep
> getting a solid yellow light on the ECU (The light means turn idle speed
> adjustment 1/4 turn counter clockwise which I think means lower the idle
> speed) whenever I rev the car at a steady rpm for a long time, like 30
> seconds.  ~30 seconds keeps coming up again and again with the ECU by the
> way (seems to be the amount of time before the computer will switch into
> open loop after a sensor is disconnected).  If I let it idle without
> revving it at all the light will not go on. Some sensor must be broken I
> think... My guess would be that the car thinks it's idling at whatever rpm
> I hold it at.  Of course I have the throttle halfway to the floor. When
the
> car stays at 4000rpm for like 30 seconds it must think that 4000rpm is the
> current idle speed. So my question is, what does the ECU use to determine
> that the idle speed is incorrect? Or rather, how does it know that the
> engine is idling? I am assuming that the ECU determines that the car is
> idling indirectly from several sensors.
>
> Incidentally, I noticed this when I was watching the o2sensor voltages
with
> a DMM.  At idle the o2 sensors swing between .35v and 0.70v in closed
loop.
> In open loop they are 0.75v +/- 0.08v usually. When I rev the engine the
o2
> sensors read a steady 0.7v in what I believe is closed loop (I take the
> rpms up slowly since I realize the ECU will go into open loop if I floor
it).
>
> Also, I believe this idle speed weirdness is the reason why I am able to
> pass the idle test for smog but not the 2500rpm test.
>
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