1998 Corolla VE: Are there any sensors in the throttle body area? [Toyota]

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From: Ray O on 18 Feb 2010 15:08

"Thee Chicago Wolf [MVP]" <.@.> wrote in message
news:7hvqn5hn5mch7kgdoor45p766gre0f91t2(a)4ax.com...
> Hi all,
>
> Are there any sensors in the area of the throttle body? If so, are
> they easy to change?
>
> Thanks much for any replies.
>
> - Thee Chicago Wolf [MVP]

Off the top of my head, the only sensor I can think of in the throttle body
is the throttle position sensor. It is easy to change but not so easy to
adjust correctly after installing it but that shouldn't really be a problem
because throttle position sensors do not fail often.

Why do you ask?
--

Ray O
(correct punctuation to reply)

From: Jeff Strickland on 18 Feb 2010 15:42

From: Ray O on 22 Feb 2010 18:04

"Thee Chicago Wolf [MVP]" <.@.> wrote in message
news:h345o5lmfib8vvj5esld4bvohh60rmmuig(a)4ax.com...
> >"Thee Chicago Wolf [MVP]" <.@.> wrote in message
>>news:7hvqn5hn5mch7kgdoor45p766gre0f91t2(a)4ax.com...
>>> Hi all,
>>>
>>> Are there any sensors in the area of the throttle body? If so, are
>>> they easy to change?
>>>
>>> Thanks much for any replies.
>>>
>>> - Thee Chicago Wolf [MVP]
>>
>>Off the top of my head, the only sensor I can think of in the throttle
>>body
>>is the throttle position sensor. It is easy to change but not so easy to
>>adjust correctly after installing it but that shouldn't really be a
>>problem
>>because throttle position sensors do not fail often.
>>
>>Why do you ask?
>
> It's on my wife's car and I thought it had something to do with her
> check engine light. I say it because passing emissions I use the
> time-tested unplug the battery trick and am usually able to go 35-40
> miles before the light comes back on. I'd recently had some work done
> on her car and the mechanic said that the throttle body looked like it
> had never been serviced/cleaned and he used practically a whole can of
> cleaner degunking it. After this, I'd reset the check engine light and
> it didn't come back on for nearly 140 miles so I thought there might
> be something to it. HOWEVER, it recently came to my attention that
> there was a Federal lawsuit on 96-2002 Toyota's for EVAP related
> issues and to my knowledge my wife never got any recall noticed or
> ever had it serviced so I think that's all it is. I'd once replaced
> the gas cap with a new one thinking that might have been it but
> apparently it wasn't it either. Autozone scanned it once and they said
> it was the Coolant Temp Sensor but I replaced that and it didn't fix
> it either. I'm pretty sure it's the EVAP related thing.
>
> The recall I am referring to is this one:
> http://www.epa.gov/compliance/resources/cases/civil/caa/toyota.html
>
> - Thee Chicago Wolf [MVP]

There are basically 3 types of faults that will illuminate the check engine
light (technically known as a Malfunction Indicator Light, or "MIL"). On
the first type of fault, the computer has to see the same problem on 2
consecutive trips to avoid turning on the MIL for a random problem. Most
evap system faults have 2 trip detection logic.

The next type of fault has 1 trip detection logic, and as the name implies,
the computer only has to see the problem once to illuminate the MIL. An
example of this might be no signal from the vehicle's speed sensor.

The third type of fault is one that will damage the engine or transmission,
and the MIL will flash instead of just being steadily illuminated. The
computer will go into a failsafe mode and the vehicle should not be driven.

Back to MIL diagnosis... When you pull the main EFI fuse or clear the MIL
with a code scanner, the computer has to go through a system readiness
check, where basically, it wants to see a signal from every sensor, and in
the case of systems with 2 trip detection logic, see signals from those
sensors on 2 consecutive trips. There is a specific definition of "trip,"
where every sensor in the vehicle has a chance to warm up and do its magic.

The EVAP or evaporative emissions control system is designed to trap fumes
that would escape from the vehicle even while it is parked, mainly fumes
from the gas tank. The system checks to make sure that the gas tank is
sealed, and then a charcoal canister absorbs and stores fuel vapors. When
the engine is cold and started, the fumes are purged from the charcoal
canister and burned in the engine. Depending on the specific trouble code,
the problem could be that purge function is not operating correctly.

Rather than guess at what the specific problem on your wife's car is, the
smart thing to do is to have the codes scanned for free at someplace like
Autozone, write down the specific numerical codes, and post them here.
Although the codes point to systems like EVAP, there is a way to test just
about every sensor and actuator to see what actually needs replacing. If
you have the specific codes, I can try to explain how to check the related
parts.

Are you a hockey player for the team that your signature suggests? I happen
to work fairly close to where that team plays and live close to where the
team practices. I have a code scanner and can pull the codes for you as it
only takes about 30 seconds. (no charge).
--

Ray O
(correct punctuation to reply)

From: Jeff Strickland on 22 Feb 2010 19:38

"Thee Chicago Wolf [MVP]" <.@.> wrote in message
news:df45o51qs6mrqr473aldr3pml8ho8r0h07(a)4ax.com...
> >"Thee Chicago Wolf [MVP]" <.@.> wrote in message
>>news:7hvqn5hn5mch7kgdoor45p766gre0f91t2(a)4ax.com...
>>> Hi all,
>>>
>>> Are there any sensors in the area of the throttle body? If so, are
>>> they easy to change?
>>>
>>> Thanks much for any replies.
>>>
>>> - Thee Chicago Wolf [MVP]
>>
>>
>>Why would you want to change it?
>
> It's on my wife's car and I thought it had something to do with her
> check engine light. I say it because passing emissions I use the
> time-tested unplug the battery trick and am usually able to go 35-40
> miles before the light comes back on. I'd recently had some work done
> on her car and the mechanic said that the throttle body looked like it
> had never been serviced/cleaned and he used practically a whole can of
> cleaner degunking it. After this, I'd reset the check engine light and
> it didn't come back on for nearly 140 miles so I thought there might
> be something to it. HOWEVER, it recently came to my attention that
> there was a Federal lawsuit on 96-2002 Toyota's for EVAP related
> issues and to my knowledge my wife never got any recall noticed or
> ever had it serviced so I think that's all it is. I'd once replaced
> the gas cap with a new one thinking that might have been it but
> apparently it wasn't it either. Autozone scanned it once and they said
> it was the Coolant Temp Sensor but I replaced that and it didn't fix
> it either. I'm pretty sure it's the EVAP related thing.
>
> The recall I am referring to is this one:
> http://www.epa.gov/compliance/resources/cases/civil/caa/toyota.html
>
> - Thee Chicago Wolf [MVP]

Before you do ANYTHING with the Check Engine Light, you have to find out WHY
it is on. You MUST pull codes before you pick up a wrench.

I suggest buying your own scan tool, you can get one for about $75 that will
do most of the stuff that people are likely to even want to try to address
at home. You can spend more if you want more information, but any scan tool
is better than none.

The Check Light can come on for literally hundreds of different reasons, and
if you're inclined to buy a shopping cart full of parts in the hopes that
one of them will fix the problem, you'd be better off buying a scan tool and
then buying the right part.

99% of the time, the scan tool will point you in the right direction and the
first part you buy is the last part you will need to buy. There are
occasions where an upstream sensor makes a downstream sensor throw a code,
but it's a relative rarity for this to happen.

If you pull codes and the engine seems to be running fine, then make a list
of the codes that come up, then reset them -- the scan tool will do this for
you. Drive a while and if the light comes on again, pull codes again and
write a new list. Fix whatever is on both of the lists. That generally works
pretty well.

There are tests you can do, or you can trust that the car will tell you
where it hurts. Personally, I've had excellent results doing what the
machine tells me to do. I've never had the computer tell me the Framis Riser
Control is on the fritz, then found that it was downstream from the Whatzit
Valve, which was the real problem. Be aware, this does happen, but it hasn't
happened to me.

From: Jeff Strickland on 22 Feb 2010 19:43

"Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message
news:hlv2ib$gf2$1(a)news.eternal-september.org...
>
> "Thee Chicago Wolf [MVP]" <.@.> wrote in message
> news:h345o5lmfib8vvj5esld4bvohh60rmmuig(a)4ax.com...
>> >"Thee Chicago Wolf [MVP]" <.@.> wrote in message
>>>news:7hvqn5hn5mch7kgdoor45p766gre0f91t2(a)4ax.com...
>>>> Hi all,
>>>>
>>>> Are there any sensors in the area of the throttle body? If so, are
>>>> they easy to change?
>>>>
>>>> Thanks much for any replies.
>>>>
>>>> - Thee Chicago Wolf [MVP]
>>>
>>>Off the top of my head, the only sensor I can think of in the throttle
>>>body
>>>is the throttle position sensor. It is easy to change but not so easy to
>>>adjust correctly after installing it but that shouldn't really be a
>>>problem
>>>because throttle position sensors do not fail often.
>>>
>>>Why do you ask?
>>
>> It's on my wife's car and I thought it had something to do with her
>> check engine light. I say it because passing emissions I use the
>> time-tested unplug the battery trick and am usually able to go 35-40
>> miles before the light comes back on. I'd recently had some work done
>> on her car and the mechanic said that the throttle body looked like it
>> had never been serviced/cleaned and he used practically a whole can of
>> cleaner degunking it. After this, I'd reset the check engine light and
>> it didn't come back on for nearly 140 miles so I thought there might
>> be something to it. HOWEVER, it recently came to my attention that
>> there was a Federal lawsuit on 96-2002 Toyota's for EVAP related
>> issues and to my knowledge my wife never got any recall noticed or
>> ever had it serviced so I think that's all it is. I'd once replaced
>> the gas cap with a new one thinking that might have been it but
>> apparently it wasn't it either. Autozone scanned it once and they said
>> it was the Coolant Temp Sensor but I replaced that and it didn't fix
>> it either. I'm pretty sure it's the EVAP related thing.
>>
>> The recall I am referring to is this one:
>> http://www.epa.gov/compliance/resources/cases/civil/caa/toyota.html
>>
>> - Thee Chicago Wolf [MVP]
>
> There are basically 3 types of faults that will illuminate the check
> engine light (technically known as a Malfunction Indicator Light, or
> "MIL"). On the first type of fault, the computer has to see the same
> problem on 2 consecutive trips to avoid turning on the MIL for a random
> problem. Most evap system faults have 2 trip detection logic.
>
> The next type of fault has 1 trip detection logic, and as the name
> implies, the computer only has to see the problem once to illuminate the
> MIL. An example of this might be no signal from the vehicle's speed
> sensor.
>
> The third type of fault is one that will damage the engine or
> transmission, and the MIL will flash instead of just being steadily
> illuminated. The computer will go into a failsafe mode and the vehicle
> should not be driven.
>
> Back to MIL diagnosis... When you pull the main EFI fuse or clear the MIL
> with a code scanner, the computer has to go through a system readiness
> check, where basically, it wants to see a signal from every sensor, and in
> the case of systems with 2 trip detection logic, see signals from those
> sensors on 2 consecutive trips. There is a specific definition of "trip,"
> where every sensor in the vehicle has a chance to warm up and do its
> magic.
>
> The EVAP or evaporative emissions control system is designed to trap fumes
> that would escape from the vehicle even while it is parked, mainly fumes
> from the gas tank. The system checks to make sure that the gas tank is
> sealed, and then a charcoal canister absorbs and stores fuel vapors. When
> the engine is cold and started, the fumes are purged from the charcoal
> canister and burned in the engine. Depending on the specific trouble
> code, the problem could be that purge function is not operating correctly.
>
> Rather than guess at what the specific problem on your wife's car is, the
> smart thing to do is to have the codes scanned for free at someplace like
> Autozone, write down the specific numerical codes, and post them here.
> Although the codes point to systems like EVAP, there is a way to test just
> about every sensor and actuator to see what actually needs replacing. If
> you have the specific codes, I can try to explain how to check the related
> parts.
>
> Are you a hockey player for the team that your signature suggests? I
> happen to work fairly close to where that team plays and live close to
> where the team practices. I have a code scanner and can pull the codes
> for you as it only takes about 30 seconds. (no charge).
> --
>

TAKE RAY UP ON THE OFFER! Run, do not walk, to Ray's house -- okay, drive
over -- and let him give you his two cents worth.

I gave you some pretty good tips, but they really only amount to about two
cents. Ray's got at least a dime's worth of tips that he just offered.

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