Corrola when A/C on Engine output not stable?

Hi,

This issue has been botherd me since I got this 2004 Corrola. When I
turen on the A/C, the engine's output seems become not stable. The
dangerous situation is when I am tring to park the park, the egine
sometime suddenly gives out a strong push and because of the soft brake
comes with the Corrola, I will feel that the I may be lossing control
over the car and thank god every time I can just stop the car before it
hits the wall.
Then , here is the question, is it normal that with the A/C turned on,
the engine's output can suddenly increase by itself?

Thanks alot.
Feng

Sorry , typo here, I was trying to say" When I am trying to park the
car".
Sorry again for the mistake :) cause my wife was watching me typing...

feng...@yahoo.com 写�：
[color=blue]
> Hi,
>
> This issue has been botherd me since I got this 2004 Corrola. When I
> turen on the A/C, the engine's output seems become not stable. The
> dangerous situation is when I am tring to park the park, the egine
> sometime suddenly gives out a strong push and because of the soft brake
> comes with the Corrola, I will feel that the I may be lossing control
> over the car and thank god every time I can just stop the car before it
> hits the wall.
> Then , here is the question, is it normal that with the A/C turned on,
> the engine's output can suddenly increase by itself?
>
> Thanks alot.
> Feng[/color]

<fengyie@yahoo.com> wrote in message
news:1140495690.877505.288090@g47g2000cwa.googlegroups.com...[color=blue]
> Hi,
>
> This issue has been botherd me since I got this 2004 Corrola. When I
> turen on the A/C, the engine's output seems become not stable. The
> dangerous situation is when I am tring to park the park, the egine
> sometime suddenly gives out a strong push and because of the soft brake
> comes with the Corrola, I will feel that the I may be lossing control
> over the car and thank god every time I can just stop the car before it
> hits the wall.
> Then , here is the question, is it normal that with the A/C turned on,
> the engine's output can suddenly increase by itself?
>
> Thanks alot.
> Feng
>[/color]

When the AC is turned on, the engine's output does not suddenly increase by
itself. When the AC is on, the AC and engine controls may increase the idle
speed. Also, when you are turning the steering wheel at low engine speed,
the power steering pump will also send a signal to slightly increase engine
speed.
--

Ray O
(correct punctuation to reply)

I have seen a similar situation with a 97 Tercel and have always
attributed it to the "small" engine and powerful ac. It is because the
idle speed is increased automatically when the ac is switched on. If
it bothers you, I suggest you turn the ac off while parking :)

On 21 Feb 2006 11:24:11 -0800, "Jimbo" <jfroche@gmail.com> wrote:
[color=blue]
>I have seen a similar situation with a 97 Tercel and have always
>attributed it to the "small" engine and powerful ac. It is because the
>idle speed is increased automatically when the ac is switched on. If
>it bothers you, I suggest you turn the ac off while parking :)[/color]


I turn my AC off when accelerating my '92 Corolla Wagon....

LOL Only way to get to speed in a years time....

--

Scott in Florida

Thanks for you guys replies.
I think your answers make sense. I tried it out again today, when I
turned on the AC, the Idle speed is pretty high( around 1000rpm) and
the output seems to be pretty strong. I needed to spend extra effort to
stop the car by pushing the park peddle obviously harder. I hope it's
not because of the AC 's problem which causes the engine to give out
too much power.Other than that I will have to live with it. The work
around will be either turn off the AC when I am parking or use extra
caution.

Thanks,
Feng

Unlike the old days modern vehicles, that are controlled by a micro
processor, no long need to change the idle speed when load is applied to, or
removed from, the engine. The MP adjusts the fuel air ratio to handle the
increased load rather than increasing the RPMS. The RPMS should remain the
same.


mike hunt


<fengyie@yahoo.com> wrote in message
news:1140593819.238897.230430@g43g2000cwa.googlegroups.com...[color=blue]
> Thanks for you guys replies.
> I think your answers make sense. I tried it out again today, when I
> turned on the AC, the Idle speed is pretty high( around 1000rpm) and
> the output seems to be pretty strong. I needed to spend extra effort to
> stop the car by pushing the park peddle obviously harder. I hope it's
> not because of the AC 's problem which causes the engine to give out
> too much power.Other than that I will have to live with it. The work
> around will be either turn off the AC when I am parking or use extra
> caution.
>
> Thanks,
> Feng
>[/color]

Mike Hunter wrote:[color=blue]
> Unlike the old days modern vehicles, that are controlled by a micro
> processor, no long need to change the idle speed when load is applied to, or
> removed from, the engine. The MP adjusts the fuel air ratio to handle the
> increased load rather than increasing the RPMS. The RPMS should remain the
> same.[/color]

Hmm, tell that to my 03 Camry. Idle has always bumped up when the AC is
on, since the day I drove it off the lot with 11 miles on it.

[email]timbirr@mailcity.com[/email] wrote:
[color=blue]
>
>Mike Hunter wrote:[color=green]
>> Unlike the old days modern vehicles, that are controlled by a micro
>> processor, no long need to change the idle speed when load is applied to, or
>> removed from, the engine. The MP adjusts the fuel air ratio to handle the
>> increased load rather than increasing the RPMS. The RPMS should remain the
>> same.[/color]
>
>Hmm, tell that to my 03 Camry. Idle has always bumped up when the AC is
>on, since the day I drove it off the lot with 11 miles on it.[/color]

Of course...I've never seen a modern automobile with AC which
doesn't 'idle up' when the compressor cuts in, why do you suppose
they call it an 'idle up circuit'?...gee...
--

-Gord.
(use gordon in email)

Maybe I've just been unlucky in all the vehicles I've had :) Every one
of them, from a variety of manufacturers "idles up" when the a/c is
switched on. It's just more obvious with the Tercel, IME.

Perhaps you haven't looked at a modern vehicle, with the latest technology,
only at a four year old Toyota low end econobox. 800 RPMs are more than
enough to run a rotary compressor. Look at a 2004/6 Lexus and many
domestics with individual cylinder injectors and coil packs. Many do not
even have the throttle connected directly to the engine. Some modern cars
with that technology can even run perfectly fine with less than all the
cylinder ;)


mike hunt

"Gord Beaman" <gord@islandtelecom.com> wrote in message
news:onrsv1piqv21m773urk3m0e9c2mola6u5d@4ax.com...[color=blue]
> [email]timbirr@mailcity.com[/email] wrote:
>[color=green]
>>
>>Mike Hunter wrote:[color=darkred]
>>> Unlike the old days modern vehicles, that are controlled by a micro
>>> processor, no long need to change the idle speed when load is applied
>>> to, or
>>> removed from, the engine. The MP adjusts the fuel air ratio to handle
>>> the
>>> increased load rather than increasing the RPMS. The RPMS should remain
>>> the
>>> same.[/color]
>>
>>Hmm, tell that to my 03 Camry. Idle has always bumped up when the AC is
>>on, since the day I drove it off the lot with 11 miles on it.[/color]
>
> Of course...I've never seen a modern automobile with AC which
> doesn't 'idle up' when the compressor cuts in, why do you suppose
> they call it an 'idle up circuit'?...gee...
> --
>
> -Gord.
> (use gordon in email)[/color]

"Mike Hunter" <mikehunt2@mailcity.com> wrote:
[color=blue]
>Unlike the old days modern vehicles, that are controlled by a micro
>processor, no long need to change the idle speed when load is applied to, or
>removed from, the engine. The MP adjusts the fuel air ratio to handle the
>increased load rather than increasing the RPMS. The RPMS should remain the
>same.
>
>
>mike hunt
>[/color]

You sure about that Mike?...doesn't make a lot of sense to
me...I'd have thought that the idle mixture would have been set
near 'best power' for normal operation.

I always thought that the 'idle up' circuit just increased the
idle speed somewhat by opening the butterfly slightly so that the
added load of the compressor wouldn't 'bog the engine down'.

Doesn't make sense to have the idle MIXTURE set so as to provide
the 'idle up' feature.
--

-Gord.
(use gordon in email)

It is apparent if the vehicle has a tack. Newer vehicles, primary from
Toyota and Ford, hold the idle around 800 RPMS. When one moves the gear
selector, the idle will drop down for an instant, then come back to 800.
After selecting neutral the opposite takes place. Start the AC and it will
once again drop down for an instant then come back to 800. Then the opposite
takes place when the AC is turned off. It is all done within the MP as it
detects the increased or decreased torque and adjust the F/A ratio. Better
fuel economy and reduced pollution are obtained by doing it in that manor.

That is the beauty of the most modern MPs. Once the vehicle is up to
operating temperature the 02 sensor sends a controlling signal to the MP,
over a range of 4 to 20 milli-amps, (1V to 5V,) all the time to maintain the
most efficient F/A ratio in all situations, based on the other four of five
imputs , . That is why the throttle is connected to the MP and no longer
directly to the engine fuel supply. With the old carburetors the throttle
controlled air flow. With the first injectors it controlled fuel flow, now
it simply controls demands for more of less torque and the MP sets the F/A
ratio to suit that demand. That is why big V8 engines today, like the 300
HP 300 FP of tongue in my Mustang GT, get 25 MPG or more with ease. They
produce gobs of torque and more than adequate HP with minimum fuel demand
;)


mike hunt


"Gord Beaman" <gord@islandtelecom.com> wrote in message
news:kr5vv1do514ttvprtn980qdng9hl5p907o@4ax.com...[color=blue]
> "Mike Hunter" <mikehunt2@mailcity.com> wrote:
>[color=green]
>>Unlike the old days modern vehicles, that are controlled by a micro
>>processor, no long need to change the idle speed when load is applied to,
>>or
>>removed from, the engine. The MP adjusts the fuel air ratio to handle the
>>increased load rather than increasing the RPMS. The RPMS should remain
>>the
>>same.
>>
>>
>>mike hunt
>>[/color]
>
> You sure about that Mike?...doesn't make a lot of sense to
> me...I'd have thought that the idle mixture would have been set
> near 'best power' for normal operation.
>
> I always thought that the 'idle up' circuit just increased the
> idle speed somewhat by opening the butterfly slightly so that the
> added load of the compressor wouldn't 'bog the engine down'.
>
> Doesn't make sense to have the idle MIXTURE set so as to provide
> the 'idle up' feature.
> --
>
> -Gord.
> (use gordon in email)[/color]