[Supras] richness under boost

[joe at wilmcd.com]

As I said, many cars use wideband sensors as stock sensors. As long as the
sensor is self-heated it won't collect carbon deposits etc. You can NOT
install a wideband sensor and drive the car with it not heated. You will
ruin the $80+ sensor. I don't know where you are getting information that
you can't run wideband sensors all of the time. Probably someone trying to
sell you something if I was to guess.

-Joe

> The reading has been confirmed using both a Marquete and Sun A/F thermal
> conductivity ratio meter carried in the car with a tube run to the
> exhaust.  (Yeah, I do get weird looks, like I'm trying to commit suicide
> in a contrived way).  Both types of devices indicate between 9.0 and 9.5:1
> A/F ratio.  Both thermal conductivity meters are sensitive to extremes in
> gas velocity, so standard practice is to pinch the hose just before
> getting off the gas, and then read the meter.  The problem with a
> wideband, as I'm told, is that you cannot leave it in place all of the
> time due to temperature considerations.
>
> Bernie
>>
>> Bernie, please do not tell us you are using this gadget to determine
>> a/f ratio.
>>
>> http://www.3barracing.com/product_3.htm
>>
>> You NEED a proper wideband sensor for tuning.
>>
>> BTW, stock pistons have made 500rwhp reliably daily driven for years.
>>
>> On Mon, Nov 05, 2007 at 10:51:56AM -0500, Walker, Brian (Rich. Dist)
>> wrote:
>>>
>>> Bernie, those spikes in boost seem a bit odd to me. I have a wideband
>>> that measures press. and has peak storage. My peak boost is always
>>> ~14.5
>>> (within ~.2 psi depending on ambient temps, ball & spring controller)
>>> This is also the pressure I normally see under WOT (by autometer gauge
>>> and real time Wideband display. To me spikes of 2-3 psi seem off. Have
>>> you checked to make sure there is no play in the WG arm? Maybe that
>>> variance is normal for other folks but my peak boost has been pretty
>>> rock solid. (peak A/F on the other hand does tend to vary a little,
>>> normally 9.6:1 -10.3:1 depending on weather)
>>> Brian W
>>>
>>> Date: Sat, 03 Nov 2007 18:59:37 -0500
>>> From: "berniek at technicaldevelop.com" <berniek at technicaldevelop.com>
>>> Subject: [Supras] richness under boost
>>> To: "Supras at supras.com" <Supras at supras.com>
>>> Message-ID: <472D0B69.9090809 at technicaldevelop.com>
>>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>>
>>> Today, I temporarily wired up a Dawes A/F indicator, and found that as
>>> expected, the engine runs richer under boost than needed for best
>>> power.
>>> There are ways I will be considering to lower combustion temperatures,
>>> such as water injection (already have the RV water pump).
>>> But for now, the Dawes readout always has the blue LED lit under boost,
>>> I guess the way Toyota intended it (about 9:1 A/F ratio).  The car
>>> feels
>>> good, so I'd rather be safe than sorry, but can use any number of means
>>> to get the A/F up to about 11:1 under boost.  I'm particularly
>>> concerned
>>> about safety since I'm running the stock pistions at 15 PSI, with one
>>> second long spikes up to 17-18 PSI.  Has 550cc, Lex, 3" exhaust, 57
>>> trim
>>> turbo, Walbro and the usual mods which go along with these parts.
>>>
>>>
>>> As always, any information would be appreciated.
>>>
>>>
>>> Berniek
>>>
>>>
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>>
>
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