Re: Idle richness with 7747.

[Shannen Durphey <shannen@grolen.com>]

Kevin Reynolds wrote:
> 
> No vacuum leaks I can find, just synced the TBIs, fresh plugs etc...
> Yes the open loop idle is in O2mv's
> I have a scanner, but have been using the open loop chip in combo with a
> dash mounted autometer AFR gauge to make it easier to monitor O2 readings
> while driving.
> I've also checked the AFR and vacuum gauges against the scanner and am right
> on with the O2 and off by 1inch on the vacuum.(20 reads as 21)
> The fuel pressure is at 12psi, and since it can bring the 02 readings in
> check once in closed loop there should be a way of doing this without having
> to drop the pressure.

The idea is to get open BL as close to 128 as possible.  The accepted
range from GM is 128+/-10, so your calibration is still too rich, even
though the O2 is able to correct it.

> When I was running the closed loop enabled bin my BLMs where around 108, at
> high vacuum and go leaner as the vacuum dropped. 
<snip>
> Since it does this, I assume it's
> trying to hit a AFR target (say 14 to 1)that is off due to my setup and is
> more like 12.5 to 1. 
You realize that as far as the ECM is concerned, it is hitting
14.7:1.  Without the feedback from the O2 sensor, it just calculates
fuel delivery based on the numbers in the prom.

I've tried the AFR vs coolant map, changing from 13 to
> 15 from about 160degrees to over 200 and the O2 gauge didn't move even 50mv.
> I did noticed there's a max and min AFR open loop setting listed in the
> winbin file I'm using that isn't listed in tunercat. I thought maybe I hit a
> cap and that was the reason for now change. So far I've only tried one burn
> shifting the caps, but didn't get any change, but it needs more exploring.
You might try dropping fuel pressure to confirm that the O2 voltage
will change at idle.  Not a bad idea to know that the result your
looking for is attainable.  One trick to get the sensor hot is to
bring rpm up to around 1500-2000 for a minute or so, until the O2
gauge starts showing changes, then let the car idle.  The sensor will
stay hot enough to keep sending a signal.
Shannen
> 
> Kevin R
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