'98 Tacoma Bad Hesitation

"al" <abuonag.DeleteThis@msn.com> wrote in message
news:1194052016.066556.162760@z9g2000hsf.googlegroups.com...
> On Nov 2, 12:01 pm, Mcgiiver <case....DeleteThis@earthlink.net> wrote:
>> I have a '98 Tacoma with the 2.7 l engine. It idles fine and runs ok
>> at high speed , but right off idle it hesitates badly. Any ideas what
>> to look at to solve this problem? There are no obvious vacuum leaks in
>> hoses. I need help badly as driveability is getting bad.
>
> Presuming it's fuel injected, an aging oxygen sensor that is beginning
> to get lazy can cause this symptom. The sensor no longer switches
> rapidly enough at idle causing a non-optimal idle mixture which
> manifests itself in a hesitation when coming off idle. If you have a
> scan tool you can watch the oxygen sensor behavior to determine if
> that is the problem. Good luck. Al
>

Wouldn't that trigger the check engine light? Most everything does on that
system.
 >> Stay informed about: '98 Tacoma Bad Hesitation 

On Nov 3, 10:19 am, "Sam in Savannah" <georgia... RemoveThis @member.org> wrote:
> "DanG" <nos... RemoveThis @q.com> wrote in message
>
> news:6u-dnVrJT8pib7banZ2dnUVZ_h-vnZ2d@comcast.com...
>
>
>
>
>
> > "al" <abuo... RemoveThis @msn.com> wrote in message
> >news:1194052016.066556.162760@z9g2000hsf.googlegroups.com...
> >> On Nov 2, 12:01 pm, Mcgiiver <case... RemoveThis @earthlink.net> wrote:
> >>> I have a '98 Tacoma with the 2.7 l engine. It idles fine and runs ok
> >>> at high speed , but right off idle it hesitates badly. Any ideas what
> >>> to look at to solve this problem? There are no obvious vacuum leaks in
> >>> hoses. I need help badly as driveability is getting bad.
>
> >> Presuming it's fuel injected, an aging oxygen sensor that is beginning
> >> to get lazy can cause this symptom. The sensor no longer switches
> >> rapidly enough at idle causing a non-optimal idle mixture which
> >> manifests itself in a hesitation when coming off idle. If you have a
> >> scan tool you can watch the oxygen sensor behavior to determine if
> >> that is the problem. Good luck. Al
>
> > Wouldn't that trigger the check engine light? Most everything does on that
> > system.
>
> Clean the throttle body!- Hide quoted text -
>
> - Show quoted text -

maybe a throttle sensor. about $50 DIY.
 >> Stay informed about: '98 Tacoma Bad Hesitation 

"DanG" <nospam.DeleteThis@q.com> wrote in message
news:6u-dnVrJT8pib7banZ2dnUVZ_h-vnZ2d@comcast.com...
>
> "al" <abuonag.DeleteThis@msn.com> wrote in message
> news:1194052016.066556.162760@z9g2000hsf.googlegroups.com...
>> On Nov 2, 12:01 pm, Mcgiiver <case....DeleteThis@earthlink.net> wrote:
>>> I have a '98 Tacoma with the 2.7 l engine. It idles fine and runs ok
>>> at high speed , but right off idle it hesitates badly. Any ideas what
>>> to look at to solve this problem? There are no obvious vacuum leaks in
>>> hoses. I need help badly as driveability is getting bad.
>>
>> Presuming it's fuel injected, an aging oxygen sensor that is beginning
>> to get lazy can cause this symptom. The sensor no longer switches
>> rapidly enough at idle causing a non-optimal idle mixture which
>> manifests itself in a hesitation when coming off idle. If you have a
>> scan tool you can watch the oxygen sensor behavior to determine if
>> that is the problem. Good luck. Al
>>
>
> Wouldn't that trigger the check engine light? Most everything does on that
> system.
>
Clean the throttle body!
 >> Stay informed about: '98 Tacoma Bad Hesitation 

On Nov 2, 11:04 pm, "DanG" <nos....TakeThisOut@q.com> wrote:
> "al" <abuo....TakeThisOut@msn.com> wrote in message
>
> news:1194052016.066556.162760@z9g2000hsf.googlegroups.com...
>
> > On Nov 2, 12:01 pm, Mcgiiver <case....TakeThisOut@earthlink.net> wrote:
> >> I have a '98 Tacoma with the 2.7 l engine. It idles fine and runs ok
> >> at high speed , but right off idle it hesitates badly. Any ideas what
> >> to look at to solve this problem? There are no obvious vacuum leaks in
> >> hoses. I need help badly as driveability is getting bad.
>
> > Presuming it's fuel injected, an aging oxygen sensor that is beginning
> > to get lazy can cause this symptom. The sensor no longer switches
> > rapidly enough at idle causing a non-optimal idle mixture which
> > manifests itself in a hesitation when coming off idle. If you have a
> > scan tool you can watch the oxygen sensor behavior to determine if
> > that is the problem. Good luck. Al
>
> Wouldn't that trigger the check engine light? Most everything does on that
> system.

It might or might not set a code depending on how sluggish the oxygen
sensor is and what the ECM logic is that triggers a code. If there
are two oxygen sensors in your set-up, one in front of the catalytic
converter and one behind the converter, the ECM will compare the
switching rates between the two. A sufficiently sluggish front sensor
can trigger a code (a catalyic converter code by the way and not an
oxygen sensor code) if the two switching rates are far enough apart.
If there's only one oxygen sensor, an oxygen sensor code will be
triggered if the switching rate falls below a threshold. It all
depends on how sluggish the sensor is and what the ECM logic is. A
factory service manual should provide that information and a scan tool
can monitor the sensor switching activity. Both are extremely useful,
sometimes essential, to diagnosing such problems. Good luck. Al
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