TBI on Toyota I6

[TomQ]

Shannen Durphey wrote:
Shannen thanks for replying.........

> I think it would be a good idea to find out what is not right during warmup.  Is
> the engine too lean?

My guess is to lean..

> Too rich?  Too low an idle speed?  Something completely
> unrelated?
>
> Do you have a scan tool?

Yep

> You might look at block learn when warm to give a
> rough indication of where the fuel curve is.

Will do.

> Consider what you need to do to
> keep the engine running while cold.

Mashing the throttle down it sputters and then takes off. I am guessing that that
means the loop opens and the mixture goes richer.

> Is it just a matter of holding the throttle
> open more?  Does black smoke pour out of the tailpipe?

No

> Does it start and die
> repeatedly?

no

> Does it pop through the throttle body on acceleration?

Pop or sputter, yes.

> Sometimes the smallest changes can make the largest differences.  But you will
> probably need to modify the calibration more than once to get an acceptable
> idle.
>
> BTW, what are you using for a throttle body?  Which injectors?

It is a Chevy TBI 4.3L on a Toyota 4.2L I6.

My guess is that since it runs when first started it is because it is in an open
loop mode and running rich. Then the computer starts to use the maps and they are to
lean for my motor. Mashing the throttle helps because the computer then changes the
mixture to rich. After the O2 sensor is warmed up the computer runs in the closed
loop mode and compensates for the lean mixture. Although, it doesn't compensate
fully because it does occasionally stutter a little and also seams to lack power in
the 1-2K rpm area.
--
TomQ
SF,CA


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