94 4cyl runs rough when cold

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Old 29 Feb 2004, 05:22 am   #1 (permalink)
Peter Jakacki
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Default 94 4cyl runs rough when cold

Hi,
I've got a 94 4cyl Camry which lately has been running rough when it's
cold. Sometimes it starts-up fine but it takes a few minutes of driving
before it comes good. It goes through a short period where it lurches in and
out of power before it starts to settle down. Sounds like it's only running
on 2 or 3 cylinders when it does play up.

I haven't had a proper look at it yet but in the meantime has anybody got
any ideas what this could be?

TIA
Peter
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Old 29 Feb 2004, 06:27 am   #2 (permalink)
IceMan
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Default Re: 94 4cyl runs rough when cold

Notes to consider:
1) 94 Camry 4 cyl does not have (OBD II) onboard diagnostic system but OBD
I.
2) O2 Sensor is 2 wires, that is no heating ckt involved to ( > 2 minutes to
become functioning.)
3) Engine runs on open loop when cold until O2 sensor heats up to 600F, that
is, AIR/FUEL ratio is set to a default setting but is not monitored or
corrected
4) Once O2 Sensor is functioning (O2 sensor temp > 600F), Engine will enter
closed loop and would control AIR/Fuel ratio.

Suggestions:
Look for short or excess air entering throttle body that impacts A/F ratio,
following are possibilities
1- Air filter but impact is not limited to cold engine
2- EGR Valve stuck open, impact is noticed when engine is cold.
3-



"Peter Jakacki" <cyb@ihug.com.au> wrote in message
news:4041CB93.DAF0C1CD@tpg.com.au...
> Hi,
> I've got a 94 4cyl Camry which lately has been running rough when it's
> cold. Sometimes it starts-up fine but it takes a few minutes of driving
> before it comes good. It goes through a short period where it lurches in

and
> out of power before it starts to settle down. Sounds like it's only

running
> on 2 or 3 cylinders when it does play up.
>
> I haven't had a proper look at it yet but in the meantime has anybody got
> any ideas what this could be?
>
> TIA
> Peter



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Old 29 Feb 2004, 01:35 pm   #3 (permalink)
Philip®
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Default Re: 94 4cyl runs rough when cold

In news:4041CB93.DAF0C1CD@tpg.com.au,
Peter Jakacki <cyb@ihug.com.au> being of bellicose mind posted:
> Hi,
> I've got a 94 4cyl Camry which lately has been running rough when
> it's cold. Sometimes it starts-up fine but it takes a few minutes
> of driving before it comes good. It goes through a short period
> where it lurches in and out of power before it starts to settle
> down. Sounds like it's only running on 2 or 3 cylinders when it
> does play up.
>
> I haven't had a proper look at it yet but in the meantime has
> anybody got any ideas what this could be?
>
> TIA
> Peter


In the old days..... we'd put the car on a scope and check the
ignition system for faulty secondary ignition components ... plugs,
plug caps arcing, plug wires, water inside the distributor cap ...
simple stuff like that. ;-)

--

- Philip @ Maximum Torque RPM



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Old 01 Mar 2004, 08:55 am   #4 (permalink)
Daniel M. Dreifus
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Default Re: 94 4cyl runs rough when cold

Peter Jakacki <cyb@ihug.com.au> wrote in message news:<4041CB93.DAF0C1CD@tpg.com.au>...
> Hi,
> I've got a 94 4cyl Camry which lately has been running rough when it's
> cold.


Same thing happens to my '94 4 cylinder occasionally, even though the
idle air control valve (and air intake hose) was replaced by the
Dealer prior to my purchase of the car.
The idle air control valve (IAC) controls the fast idle speed when
cold by passing a small amount of air past the closed throttle valve.
(Kind of amazing operation really. Computer controlled "step"motor
moves a pintel valve to maintain the idle speed at correct values for
all conditions.)
Sometimes the valve gets gummed up and doesn't open fully to let in
more air when cold to create the fast idle necessary immediately after
starting.
Just take a 10mm wrench, loosen the hose clamp and pull the plastic
air intake hose to the throttle body over to one side.
Start the engine and let it idle roughly.
Spray short blasts of emissions control safe carburetor cleaner into
the small rectangular hole on the bottom, just right of center, in
front of the butterfly valve. This is the air intake for the IAC.
Keep the engine running if needed by moving the throttle cable on the
left side of the throttle body.
Had to do this again couple of days ago, but will be many months
before needed again.
Purists will tell you it is necessary to remove the throttle body and
IAC valve for thorough cleaning, and you can have the dealer do this
for you also.
I use a small amount of Berryman carb. cleaner (apx. $3 per can) every
six months or so, versus around $80 for the throttle body cleaning,
which also is not a permanent cure.
To "properly" clean the IAC valve you need to break the seal at the
gasket, remove the water lines and cables. Not really a major job, but
certainly more involved than one hose clamp bolt and a few minutes
time.
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Old 01 Mar 2004, 10:33 am   #5 (permalink)
Philip®
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Default Re: 94 4cyl runs rough when cold

In news:c5ef7dc0.0403010655.4b7b5d1@posting.google.co m,
Daniel M. Dreifus <nospampls2002@yahoo.com> being of bellicose mind
posted:
> Peter Jakacki <cyb@ihug.com.au> wrote in message
> news:<4041CB93.DAF0C1CD@tpg.com.au>...
> > Hi,
> > I've got a 94 4cyl Camry which lately has been running rough
> > when it's cold.


>snip<
> Purists will tell you it is necessary to remove the throttle body
> and
> IAC valve for thorough cleaning, and you can have the dealer do
> this
> for you also.


(Purist raises his hand)

EXCUSE me :-)

WHEN you've got highly expensive heated O2 and A/F sensors in the
exhaust, it is proper to take throttle body off the car and remove
the IAC from the throttle body for cleaning. Anyone who has
Berryman'd or Gumout'd an intake tract and then checked a spark plug
won't want all that carbon endangering those two ... sometime three
exhaust sensors.
--

- Philip @ Maximum Torque RPM


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Old 02 Mar 2004, 08:34 am   #6 (permalink)
Daniel M. Dreifus
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Default Re: 94 4cyl runs rough when cold

"Philip®" <1chip-state1@earthlink.net.invalid> wrote in message
>
> (Purist raises his hand)
>
> EXCUSE me :-)
>
> WHEN you've got highly expensive heated O2 and A/F sensors in the
> exhaust, it is proper to take throttle body off the car and remove
> the IAC from the throttle body for cleaning. Anyone who has
> Berryman'd or Gumout'd an intake tract and then checked a spark plug
> won't want all that carbon endangering those two ... sometime three
> exhaust sensors.


Thanks for your answer. Was wondering about the benefits of removing
the IAC for cleaning.
Still . . . on the '94 the first (main) O2 sensor is not heated, but
more importantly, one is not spraying and cleaning the throttle body
and releasing lots of muck into the cylinders or exhaust.
If the throttle body needs cleaning, that can be done separately, with
the engine off, and cleaning loosened gum with a rag and toothbrush.
In that case, the throttle (engine off) is fully opened, with both
front and back sides cleaned.
The distinction, when cleaning the IAC valve to correct rough running
when cold, is that the throttle is fully closed when spraying cleaner.
If the engine stumbles further, threatening to die, the throttle is
opened slightly to keep it running, but at that point is admitting
only air. I'm actually more concerned about admitting unfiltered air,
but it is only for a few minutes.
Plus, if you learn to keep the blasts of spray cleaner very short, no
manipulation of the throttle is required - just wait a few seconds for
the idle speed to clear up.
Essentially, the only "carbon endangering the oxygen sensors or spark
plugs" is the quite tiny amount of gum causing the small orifices in
the idle air control valve to stick slightly, because the cleaner
spray is directly only into the IAC air intake passageway. You're not
opening up the throttle and dousing the whole throttle body in
cleaner, just surgically aiming a mist from the little red tube to
direct a short spray into the little rectangular holes in front of the
closed butterfly valve, and that's really all it takes to clear up the
cold idle problem.
Keep going, and you might convince me to take the whole thing apart
for cleaning next time, but I suspect the results wouldn't be any
different.
Based on mileage, I did use the OX1 terminal in the DLC1 under hood
connector with a digital multimeter last month, just to check the
operation of the oxygen sensor and it appeared to be operating
correctly, with fairly rapid and consistent switching.
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Old 02 Mar 2004, 09:17 am   #7 (permalink)
Philip®
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Default Re: 94 4cyl runs rough when cold

In news:c5ef7dc0.0403020634.1f1cea13@posting.google.c om,
Daniel M. Dreifus <nospampls2002@yahoo.com> being of bellicose mind
posted:
> "Philip®" <1chip-state1@earthlink.net.invalid> wrote in message
> >
> > (Purist raises his hand)
> >
> > EXCUSE me :-)
> >
> > WHEN you've got highly expensive heated O2 and A/F sensors in the
> > exhaust, it is proper to take throttle body off the car and
> > remove the IAC from the throttle body for cleaning. Anyone who
> > has Berryman'd or Gumout'd an intake tract and then checked a
> > spark plug won't want all that carbon endangering those two ...
> > sometime three exhaust sensors.

>
> Thanks for your answer. Was wondering about the benefits of
> removing the IAC for cleaning.
> Still . . . on the '94 the first (main) O2 sensor is not heated,
> but more importantly, one is not spraying and cleaning the
> throttle body and releasing lots of muck into the cylinders or
> exhaust.
> If the throttle body needs cleaning, that can be done separately,
> with the engine off, and cleaning loosened gum with a rag and
> toothbrush. In that case, the throttle (engine off) is fully
> opened, with both front and back sides cleaned.
> The distinction, when cleaning the IAC valve to correct rough
> running when cold, is that the throttle is fully closed when
> spraying cleaner. If the engine stumbles further, threatening to
> die, the throttle is opened slightly to keep it running, but at
> that point is admitting only air. I'm actually more concerned
> about admitting unfiltered air, but it is only for a few minutes.
> Plus, if you learn to keep the blasts of spray cleaner very short,
> no manipulation of the throttle is required - just wait a few
> seconds for the idle speed to clear up.
> Essentially, the only "carbon endangering the oxygen sensors or
> spark plugs" is the quite tiny amount of gum causing the small
> orifices in the idle air control valve to stick slightly, because
> the cleaner spray is directly only into the IAC air intake
> passageway. You're not opening up the throttle and dousing the
> whole throttle body in cleaner, just surgically aiming a mist from
> the little red tube to direct a short spray into the little
> rectangular holes in front of the closed butterfly valve, and
> that's really all it takes to clear up the cold idle problem.
> Keep going, and you might convince me to take the whole thing apart
> for cleaning next time, but I suspect the results wouldn't be any
> different.
> Based on mileage, I did use the OX1 terminal in the DLC1 under hood
> connector with a digital multimeter last month, just to check the
> operation of the oxygen sensor and it appeared to be operating
> correctly, with fairly rapid and consistent switching.


You've given a bunch of excuses for not spinning off 4 or 5 bolts and
a fitting and removing the throttle body to the bench.to do the job
right. Duly noted.
--

- Philip @ Maximum Torque RPM


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Old 02 Mar 2004, 05:47 pm   #8 (permalink)
m Ransley
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Default Re: 94 4cyl runs rough when cold

When was your last tune up , how are the plugs and hows it been
maintained, could be a bad wire or a bad cilinder .

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Old 02 Mar 2004, 08:50 pm   #9 (permalink)
MUADIB®
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Default Re: 94 4cyl runs rough when cold


>
>You've given a bunch of excuses for not spinning off 4 or 5 bolts and
>a fitting and removing the throttle body to the bench.to do the job
>right. Duly noted.


And ,...........of couorse you've been helpful with this wonderful
tidbit.

( yeah, I know I am no more helpful than you were with that post, but
It's good for someone to let you know once in a while how much help
you've been )




Remove "YOURPANTIES" to reply MUADIB®

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and theirs. -- Oxford University Press, Edpress News
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Old 05 Mar 2004, 06:21 am   #10 (permalink)
IceMan
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Default Re: 94 4cyl runs rough when cold

V6 Camry has another Intake Air Control Valve located by DLC1, its part of
Acoustic Control Induction System intended to provide high torque at low RPM
when in closed position and maximum horse power at high RPM when in open
position. A valve to consider for cleaning on V6 engines.


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