Cool, thanks. As a final question (yeah, right) what changes does the
computer make in response to a cooler setting (i.e. how much would timing
and fuel metering, etc., change with a 20 degree drop in the IAT reading)?
Don't take this as questioning of your device, I'm just trying to learn how
our engines work...
- Alex
> From: bernd@texas.net
> Reply-To: dakota-truck@buffnet.net
> Date: Fri, 23 Mar 2001 09:54:09 +0000 (US/Central)
> To: dakota-truck@buffnet.net
> Subject: Re: DML: IAT box & dyno results -- tech discussion
>
>
> Our performance suffers when the engine gets warm because of the location of
> the IAT. The factory location wil read (in the summer) about 200 degrees.
> The
> adjuster box doesn't fool the computer with the amount of air (we don't have
> Mass Air Systems) but rather the temperature of the air. The temp is related
> to volume, but not close to as accurate as Mass Air.
>
> On the efficiency factor, they controllers are designed with a combination of
> power and efficiency (leaning toward fuel economy). This isn't a bad thing,
> but when trying to adjust for more power, the factory settings aren't quite
> right.
>
> On the Mopar PCM and Jet Chip, i'm not certain about Mopars compensations, but
> the Jet does alter the IAT output slightly...for $250.
>
> Why do we have an IAT sensor? Because the actual ir temp will be different
> from cold start to normal operating temp. This means slightly different
> timing
> and fuel enrichment for the cold to hot running conditions. (Just like the
> old
> Chokes on Carburetors...only without the timing part involved.)
>
> - Bernd
>
>> I have more questions about this, please bear with me here... :-)
>>
>> OK, our performance suffers when the intake air gets too warm. As I
>> understand it, the warmer the intake air temperature, the less oxygen
>> actually gets into our engines (because air expands as it gets warmer).
>>
>> Evidently, now we can compensate somewhat with the IAT adjuster, setting the
>> PCM input so it thinks it's cooler than it really is. But if the problem is
>> that we're not getting enough air, how does fooling the PCM into thinking
>> we're getting more air help? Does this mean that our computer isn't doing a
>> good job setting the A/F ratio for maximum efficiency, or is it a question
>> of optimum efficiency vs. maximum power? If it's the latter, wouldn't an
>> aftermarket computer like the Mopar PCM or Jet chip address this?
>>
>> Or is it just that the IAT gives a "false high" reading because the engine
>> compartment temps are higher than the actual air temp?
>>
>> One final question... if our engine has a temperature "setting" where it
>> runs its best, why do we have an IAT at all?
>>
>> Sorry for all the questions -- I'm just trying to get a handle on the
>> principles behind how this stuff works. :-)
>>
>> Thanks,
>>
>> - Alex
>>
>>
>
>
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