jim beam <spamvortex@bad.example.net> wrote in
news:Kv6dnSh54NJeE-_bnZ2dnUVZ_t-mnZ2d@speakeasy.net:

> Jim Yanik wrote:
>> "John Smith" <jsmith@yahoo.com> wrote in
>> news:Pcici.55$Hl2.23@newsfe12.lga:
>>
>>> Thanks, Jim. Your suggestions sound promising.
>>>
>>> Would high or low voltage out of the TPS trigger a trouble code? (I
>>> haven't had one with this problem.)
>>
>> the OUTPUT is supposed to vary with throttle position,0-~4.5V.If the
>> Reference input V went high(more than 5V),I suppose that could "set a
>> code",but I doubt it.
>> A code is probably generated if there's NO output V from the TPS.
>> Like if the ref V input failed or the TPS went open.
>>
>> If anyone knew the value of the variable resistor in the TPS,one
>> could sub a pot for it and see if that fixed(steadied) the idle.
>> Maybe a 10K or 50K linear pot.
>>> The igniter also sounds like a possible answer, especially given
>>> it's closeness to the hottest part of the engine. But replacing it
>>> will be a $130 gamble. Is there any way to test the igniter?
>>
>> Scope it's output,with an oscilloscope. See if the pulse train is too
>> jumpy or erratic.
>
> if it is, it's unlikely to be the igniter. the igniter's just an
> electronic power switch. like most other semicons, they usually
> either work, or they don't.

Since the igniter contains an IC to adjust the "dwell" time of the
transistor that is the actual power switch,it's possible for that IC to get
flaky at a high temp,or even at a narrow temp range.With electronics,
"either works or it doesn't" is not always true.

also,doesn't the igniter feed back data to the ECU,thru the tach output?


--
Jim Yanik
jyanik
at
kua.net

 

jim beam <spamvortex@bad.example.net> wrote in
news:Kv6dnSh54NJeE-_bnZ2dnUVZ_t-mnZ2d@speakeasy.net:

> Jim Yanik wrote:
>> "John Smith" <jsmith@yahoo.com> wrote in
>> news:Pcici.55$Hl2.23@newsfe12.lga:
>>
>>> Thanks, Jim. Your suggestions sound promising.
>>>
>>> Would high or low voltage out of the TPS trigger a trouble code? (I
>>> haven't had one with this problem.)
>>
>> the OUTPUT is supposed to vary with throttle position,0-~4.5V.If the
>> Reference input V went high(more than 5V),I suppose that could "set a
>> code",but I doubt it.
>> A code is probably generated if there's NO output V from the TPS.
>> Like if the ref V input failed or the TPS went open.
>>
>> If anyone knew the value of the variable resistor in the TPS,one
>> could sub a pot for it and see if that fixed(steadied) the idle.
>> Maybe a 10K or 50K linear pot.
>>> The igniter also sounds like a possible answer, especially given
>>> it's closeness to the hottest part of the engine. But replacing it
>>> will be a $130 gamble. Is there any way to test the igniter?
>>
>> Scope it's output,with an oscilloscope. See if the pulse train is too
>> jumpy or erratic.
>
> if it is, it's unlikely to be the igniter. the igniter's just an
> electronic power switch. like most other semicons, they usually
> either work, or they don't.

Since the igniter contains an IC to adjust the "dwell" time of the
transistor that is the actual power switch,it's possible for that IC to get
flaky at a high temp,or even at a narrow temp range.With electronics,
"either works or it doesn't" is not always true.

also,doesn't the igniter feed back data to the ECU,thru the tach output?


--
Jim Yanik
jyanik
at
kua.net

 

jim beam <spamvortex@bad.example.net> wrote in
news:Kv6dnSh54NJeE-_bnZ2dnUVZ_t-mnZ2d@speakeasy.net:

> Jim Yanik wrote:
>> "John Smith" <jsmith@yahoo.com> wrote in
>> news:Pcici.55$Hl2.23@newsfe12.lga:
>>
>>> Thanks, Jim. Your suggestions sound promising.
>>>
>>> Would high or low voltage out of the TPS trigger a trouble code? (I
>>> haven't had one with this problem.)
>>
>> the OUTPUT is supposed to vary with throttle position,0-~4.5V.If the
>> Reference input V went high(more than 5V),I suppose that could "set a
>> code",but I doubt it.
>> A code is probably generated if there's NO output V from the TPS.
>> Like if the ref V input failed or the TPS went open.
>>
>> If anyone knew the value of the variable resistor in the TPS,one
>> could sub a pot for it and see if that fixed(steadied) the idle.
>> Maybe a 10K or 50K linear pot.
>>> The igniter also sounds like a possible answer, especially given
>>> it's closeness to the hottest part of the engine. But replacing it
>>> will be a $130 gamble. Is there any way to test the igniter?
>>
>> Scope it's output,with an oscilloscope. See if the pulse train is too
>> jumpy or erratic.
>
> if it is, it's unlikely to be the igniter. the igniter's just an
> electronic power switch. like most other semicons, they usually
> either work, or they don't.

Since the igniter contains an IC to adjust the "dwell" time of the
transistor that is the actual power switch,it's possible for that IC to get
flaky at a high temp,or even at a narrow temp range.With electronics,
"either works or it doesn't" is not always true.

also,doesn't the igniter feed back data to the ECU,thru the tach output?


--
Jim Yanik
jyanik
at
kua.net

 

Jim Yanik wrote:
> jim beam <spamvortex@bad.example.net> wrote in
> news:Kv6dnSh54NJeE-_bnZ2dnUVZ_t-mnZ2d@speakeasy.net:
>
>> Jim Yanik wrote:
>>> "John Smith" <jsmith@yahoo.com> wrote in
>>> news:Pcici.55$Hl2.23@newsfe12.lga:
>>>
>>>> Thanks, Jim. Your suggestions sound promising.
>>>>
>>>> Would high or low voltage out of the TPS trigger a trouble code? (I
>>>> haven't had one with this problem.)
>>> the OUTPUT is supposed to vary with throttle position,0-~4.5V.If the
>>> Reference input V went high(more than 5V),I suppose that could "set a
>>> code",but I doubt it.
>>> A code is probably generated if there's NO output V from the TPS.
>>> Like if the ref V input failed or the TPS went open.
>>>
>>> If anyone knew the value of the variable resistor in the TPS,one
>>> could sub a pot for it and see if that fixed(steadied) the idle.
>>> Maybe a 10K or 50K linear pot.
>>>> The igniter also sounds like a possible answer, especially given
>>>> it's closeness to the hottest part of the engine. But replacing it
>>>> will be a $130 gamble. Is there any way to test the igniter?
>>> Scope it's output,with an oscilloscope. See if the pulse train is too
>>> jumpy or erratic.
>> if it is, it's unlikely to be the igniter. the igniter's just an
>> electronic power switch. like most other semicons, they usually
>> either work, or they don't.
>
> Since the igniter contains an IC to adjust the "dwell" time of the
> transistor that is the actual power switch,it's possible for that IC to get
> flaky at a high temp,or even at a narrow temp range.With electronics,
> "either works or it doesn't" is not always true.

the added complexity compounds the problem, not mitigates it. ever had
computer componentry flake on you? one minute it's there, next it's
gone. pow.


>
> also,doesn't the igniter feed back data to the ECU,thru the tach output?

no, the ecu relies on the sensors in the distributor for rpm input. if
you think about it, the tach line is just a phased version of the ecu's
own output - not much good for ecu feedback purposes.

 

Jim Yanik wrote:
> jim beam <spamvortex@bad.example.net> wrote in
> news:Kv6dnSh54NJeE-_bnZ2dnUVZ_t-mnZ2d@speakeasy.net:
>
>> Jim Yanik wrote:
>>> "John Smith" <jsmith@yahoo.com> wrote in
>>> news:Pcici.55$Hl2.23@newsfe12.lga:
>>>
>>>> Thanks, Jim. Your suggestions sound promising.
>>>>
>>>> Would high or low voltage out of the TPS trigger a trouble code? (I
>>>> haven't had one with this problem.)
>>> the OUTPUT is supposed to vary with throttle position,0-~4.5V.If the
>>> Reference input V went high(more than 5V),I suppose that could "set a
>>> code",but I doubt it.
>>> A code is probably generated if there's NO output V from the TPS.
>>> Like if the ref V input failed or the TPS went open.
>>>
>>> If anyone knew the value of the variable resistor in the TPS,one
>>> could sub a pot for it and see if that fixed(steadied) the idle.
>>> Maybe a 10K or 50K linear pot.
>>>> The igniter also sounds like a possible answer, especially given
>>>> it's closeness to the hottest part of the engine. But replacing it
>>>> will be a $130 gamble. Is there any way to test the igniter?
>>> Scope it's output,with an oscilloscope. See if the pulse train is too
>>> jumpy or erratic.
>> if it is, it's unlikely to be the igniter. the igniter's just an
>> electronic power switch. like most other semicons, they usually
>> either work, or they don't.
>
> Since the igniter contains an IC to adjust the "dwell" time of the
> transistor that is the actual power switch,it's possible for that IC to get
> flaky at a high temp,or even at a narrow temp range.With electronics,
> "either works or it doesn't" is not always true.

the added complexity compounds the problem, not mitigates it. ever had
computer componentry flake on you? one minute it's there, next it's
gone. pow.


>
> also,doesn't the igniter feed back data to the ECU,thru the tach output?

no, the ecu relies on the sensors in the distributor for rpm input. if
you think about it, the tach line is just a phased version of the ecu's
own output - not much good for ecu feedback purposes.

 

Jim Yanik wrote:
> jim beam <spamvortex@bad.example.net> wrote in
> news:Kv6dnSh54NJeE-_bnZ2dnUVZ_t-mnZ2d@speakeasy.net:
>
>> Jim Yanik wrote:
>>> "John Smith" <jsmith@yahoo.com> wrote in
>>> news:Pcici.55$Hl2.23@newsfe12.lga:
>>>
>>>> Thanks, Jim. Your suggestions sound promising.
>>>>
>>>> Would high or low voltage out of the TPS trigger a trouble code? (I
>>>> haven't had one with this problem.)
>>> the OUTPUT is supposed to vary with throttle position,0-~4.5V.If the
>>> Reference input V went high(more than 5V),I suppose that could "set a
>>> code",but I doubt it.
>>> A code is probably generated if there's NO output V from the TPS.
>>> Like if the ref V input failed or the TPS went open.
>>>
>>> If anyone knew the value of the variable resistor in the TPS,one
>>> could sub a pot for it and see if that fixed(steadied) the idle.
>>> Maybe a 10K or 50K linear pot.
>>>> The igniter also sounds like a possible answer, especially given
>>>> it's closeness to the hottest part of the engine. But replacing it
>>>> will be a $130 gamble. Is there any way to test the igniter?
>>> Scope it's output,with an oscilloscope. See if the pulse train is too
>>> jumpy or erratic.
>> if it is, it's unlikely to be the igniter. the igniter's just an
>> electronic power switch. like most other semicons, they usually
>> either work, or they don't.
>
> Since the igniter contains an IC to adjust the "dwell" time of the
> transistor that is the actual power switch,it's possible for that IC to get
> flaky at a high temp,or even at a narrow temp range.With electronics,
> "either works or it doesn't" is not always true.

the added complexity compounds the problem, not mitigates it. ever had
computer componentry flake on you? one minute it's there, next it's
gone. pow.


>
> also,doesn't the igniter feed back data to the ECU,thru the tach output?

no, the ecu relies on the sensors in the distributor for rpm input. if
you think about it, the tach line is just a phased version of the ecu's
own output - not much good for ecu feedback purposes.

 

Jim Yanik said the following on 6/13/2007 12:01 PM:
> "John Smith" <jsmith@yahoo.com> wrote in
> news%Sbi.12$SX1.4@newsfe12.lga:
>
>> Thanks, Spam. The fact that it always waits to start dying until
>> heating up suggests to me that something electronic is happening that
>> causes the computer instructions on where to set low idle get
>> interrupted somehow. The ignition, timing and idle all work perfectly
>> fine while the car is warming up. Also, they have been working fine on
>> short trips for the last few months. The problem only re-occured
>> after a longer drive at high speeds.
>>
>>
>> "spam" <nimbusters@centralpets.com> wrote in message
>> news:466efabb$0$5238$4c368faf@roadrunner.com...
>>> I am no expert, but I suggest you look at ignition and fuel (filter,
>>> timing, plugs, module). When was the last time you tuned it up?
>>>
>>>
>>>
>>>
>>> "John Smith" <jsmith@yahoo.com> wrote in message
>>> newseCbi.45$KN5.8@newsfe12.lga...
>>>> For almost a year I have been struggling with a recurring problem
>>>> that appears to be triggered by sustained driving on the highway.
>>>> It has come up three times now and I thought I had it fixed after
>>>> the second episode so I don't know what to try next.
>>>>
>>>> It's a 99 Accord LX 4 door 4 cyl 5-speed, 184,500 miles (lots of
>>>> highway driving).
>>>>
>>>> The problem is after the engine hits operating temperature, it
>>>> cannot idle at the bottom end -- when you slow down it just drops
>>>> off to zero RPMs and dies unless you feed it gas with the clutch
>>>> down. It first happened during an all-day drive last summer. I had
>>>> just changed the oil, filter and air filter for the trip. To try to
>>>> fix it, I replaced the spark plugs and the PCV, ran some injector
>>>> cleaner through, and replaced the coolant and the ignition coil.
>>>> That seemed to help a little and the car stopped dying so much but
>>>> still ran uncertainly at low RPMs. Then I took another long drive
>>>> (this time a warm day in December) and the same problem came back.
>>>> This time I switched out the ignition wires, distributor cap and
>>>> rotor. Lo and behold the car seemed almost back to normal. I have
>>>> driven it up to 50 miles at a time without incident. But this
>>>> weekend my son drove over an hour on the highway (warm abient temps,
>>>> too) and sure enough, it started dying again.
>>>>
>>>> There are no trouble codes being activated. I'm looking for a good
>>>> idea on what to try next and this group is a great help. Thanks in
>>>> advance for your suggestions.
>>>>
>>>
>>
>>
>
> Maybe you should monitor the reference voltage going to the Throttle
> Position Sensor(TPS)and the TPS output voltage.Perhaps the ref V is
> dropping(it's source is the ECU),or the TPS output is changing (bad TPS)and
> telling the ECU to lower the idle....to a point where it will not run
> properly.
> Take a "cold" reading on the reference V,then another when the engine
> starts to stumble. You'll have to backpin the connector.
>
> Or maybe the igniter (in the distributor)is the problem;perhaps altering
> the firing of the coil once it warms up.
>
I had a similar idle problem with a Dodge Caravan (3.0 liter Mitsubishi
Engine) that turned out to be a gummed up throttle body. There were no
engine failure lights, the idle speed would just drop to zero.

 

Jim Yanik said the following on 6/13/2007 12:01 PM:
> "John Smith" <jsmith@yahoo.com> wrote in
> news%Sbi.12$SX1.4@newsfe12.lga:
>
>> Thanks, Spam. The fact that it always waits to start dying until
>> heating up suggests to me that something electronic is happening that
>> causes the computer instructions on where to set low idle get
>> interrupted somehow. The ignition, timing and idle all work perfectly
>> fine while the car is warming up. Also, they have been working fine on
>> short trips for the last few months. The problem only re-occured
>> after a longer drive at high speeds.
>>
>>
>> "spam" <nimbusters@centralpets.com> wrote in message
>> news:466efabb$0$5238$4c368faf@roadrunner.com...
>>> I am no expert, but I suggest you look at ignition and fuel (filter,
>>> timing, plugs, module). When was the last time you tuned it up?
>>>
>>>
>>>
>>>
>>> "John Smith" <jsmith@yahoo.com> wrote in message
>>> newseCbi.45$KN5.8@newsfe12.lga...
>>>> For almost a year I have been struggling with a recurring problem
>>>> that appears to be triggered by sustained driving on the highway.
>>>> It has come up three times now and I thought I had it fixed after
>>>> the second episode so I don't know what to try next.
>>>>
>>>> It's a 99 Accord LX 4 door 4 cyl 5-speed, 184,500 miles (lots of
>>>> highway driving).
>>>>
>>>> The problem is after the engine hits operating temperature, it
>>>> cannot idle at the bottom end -- when you slow down it just drops
>>>> off to zero RPMs and dies unless you feed it gas with the clutch
>>>> down. It first happened during an all-day drive last summer. I had
>>>> just changed the oil, filter and air filter for the trip. To try to
>>>> fix it, I replaced the spark plugs and the PCV, ran some injector
>>>> cleaner through, and replaced the coolant and the ignition coil.
>>>> That seemed to help a little and the car stopped dying so much but
>>>> still ran uncertainly at low RPMs. Then I took another long drive
>>>> (this time a warm day in December) and the same problem came back.
>>>> This time I switched out the ignition wires, distributor cap and
>>>> rotor. Lo and behold the car seemed almost back to normal. I have
>>>> driven it up to 50 miles at a time without incident. But this
>>>> weekend my son drove over an hour on the highway (warm abient temps,
>>>> too) and sure enough, it started dying again.
>>>>
>>>> There are no trouble codes being activated. I'm looking for a good
>>>> idea on what to try next and this group is a great help. Thanks in
>>>> advance for your suggestions.
>>>>
>>>
>>
>>
>
> Maybe you should monitor the reference voltage going to the Throttle
> Position Sensor(TPS)and the TPS output voltage.Perhaps the ref V is
> dropping(it's source is the ECU),or the TPS output is changing (bad TPS)and
> telling the ECU to lower the idle....to a point where it will not run
> properly.
> Take a "cold" reading on the reference V,then another when the engine
> starts to stumble. You'll have to backpin the connector.
>
> Or maybe the igniter (in the distributor)is the problem;perhaps altering
> the firing of the coil once it warms up.
>
I had a similar idle problem with a Dodge Caravan (3.0 liter Mitsubishi
Engine) that turned out to be a gummed up throttle body. There were no
engine failure lights, the idle speed would just drop to zero.

 

Jim Yanik said the following on 6/13/2007 12:01 PM:
> "John Smith" <jsmith@yahoo.com> wrote in
> news%Sbi.12$SX1.4@newsfe12.lga:
>
>> Thanks, Spam. The fact that it always waits to start dying until
>> heating up suggests to me that something electronic is happening that
>> causes the computer instructions on where to set low idle get
>> interrupted somehow. The ignition, timing and idle all work perfectly
>> fine while the car is warming up. Also, they have been working fine on
>> short trips for the last few months. The problem only re-occured
>> after a longer drive at high speeds.
>>
>>
>> "spam" <nimbusters@centralpets.com> wrote in message
>> news:466efabb$0$5238$4c368faf@roadrunner.com...
>>> I am no expert, but I suggest you look at ignition and fuel (filter,
>>> timing, plugs, module). When was the last time you tuned it up?
>>>
>>>
>>>
>>>
>>> "John Smith" <jsmith@yahoo.com> wrote in message
>>> newseCbi.45$KN5.8@newsfe12.lga...
>>>> For almost a year I have been struggling with a recurring problem
>>>> that appears to be triggered by sustained driving on the highway.
>>>> It has come up three times now and I thought I had it fixed after
>>>> the second episode so I don't know what to try next.
>>>>
>>>> It's a 99 Accord LX 4 door 4 cyl 5-speed, 184,500 miles (lots of
>>>> highway driving).
>>>>
>>>> The problem is after the engine hits operating temperature, it
>>>> cannot idle at the bottom end -- when you slow down it just drops
>>>> off to zero RPMs and dies unless you feed it gas with the clutch
>>>> down. It first happened during an all-day drive last summer. I had
>>>> just changed the oil, filter and air filter for the trip. To try to
>>>> fix it, I replaced the spark plugs and the PCV, ran some injector
>>>> cleaner through, and replaced the coolant and the ignition coil.
>>>> That seemed to help a little and the car stopped dying so much but
>>>> still ran uncertainly at low RPMs. Then I took another long drive
>>>> (this time a warm day in December) and the same problem came back.
>>>> This time I switched out the ignition wires, distributor cap and
>>>> rotor. Lo and behold the car seemed almost back to normal. I have
>>>> driven it up to 50 miles at a time without incident. But this
>>>> weekend my son drove over an hour on the highway (warm abient temps,
>>>> too) and sure enough, it started dying again.
>>>>
>>>> There are no trouble codes being activated. I'm looking for a good
>>>> idea on what to try next and this group is a great help. Thanks in
>>>> advance for your suggestions.
>>>>
>>>
>>
>>
>
> Maybe you should monitor the reference voltage going to the Throttle
> Position Sensor(TPS)and the TPS output voltage.Perhaps the ref V is
> dropping(it's source is the ECU),or the TPS output is changing (bad TPS)and
> telling the ECU to lower the idle....to a point where it will not run
> properly.
> Take a "cold" reading on the reference V,then another when the engine
> starts to stumble. You'll have to backpin the connector.
>
> Or maybe the igniter (in the distributor)is the problem;perhaps altering
> the firing of the coil once it warms up.
>
I had a similar idle problem with a Dodge Caravan (3.0 liter Mitsubishi
Engine) that turned out to be a gummed up throttle body. There were no
engine failure lights, the idle speed would just drop to zero.