Loose distributor bearing (felt using fingers) may cause the sensors no
longer work properly. Because this signal must be consistent, missing a
signal or adding too many signals could cause a bad firing timing. Keep in
mind that this signal is again modified by the ECU. For example, an RPM
spiking is probaly an indication that a normal sqaure wave width has suddenly
shrunk then, afterwards, go back to normal. The technician scope can pick
this up.

I recommend looking at the distributor, ECU and it's pipeline. Replacing the
igniter is merely a patch to the real underlying problem. -The low temp is
just probably an open thermostat.
Indi

>"Honda" <tjc@charter2.net>
> I have a 1993 Honda Civic that recently started displaying some weird
> ignition related problems.
>
> I noticed that sometimes the tach ocaissionally spikes during operation.
> The car also started to run rough one day and proceeded to get worse. I
> replaced the ignition module (the one in the distributor) and it fixed the
> problem (temporarily). About a month later, same thing (replaced another
> module). I have done this several times.
>
> I noticed that the car is running cooler than usual, and suspect a bad
> thermostat.
>
> My question is:
>
> Can a bad thermostat causing a low coolant temperature cause the kinds of
> problems with the ignition I am decribing here? (Theroetically, the
coolant
> temperature switch doesn't get hot enough, maybe causing the ignition to
> deliver too hot of a spark all the time, causing it to die prematurely?)
>
> HELP!
>
>

 

Loose distributor bearing (felt using fingers) may cause the sensors no
longer work properly. Because this signal must be consistent, missing a
signal or adding too many signals could cause a bad firing timing. Keep in
mind that this signal is again modified by the ECU. For example, an RPM
spiking is probaly an indication that a normal sqaure wave width has suddenly
shrunk then, afterwards, go back to normal. The technician scope can pick
this up.

I recommend looking at the distributor, ECU and it's pipeline. Replacing the
igniter is merely a patch to the real underlying problem. -The low temp is
just probably an open thermostat.
Indi

>"Honda" <tjc@charter2.net>
> I have a 1993 Honda Civic that recently started displaying some weird
> ignition related problems.
>
> I noticed that sometimes the tach ocaissionally spikes during operation.
> The car also started to run rough one day and proceeded to get worse. I
> replaced the ignition module (the one in the distributor) and it fixed the
> problem (temporarily). About a month later, same thing (replaced another
> module). I have done this several times.
>
> I noticed that the car is running cooler than usual, and suspect a bad
> thermostat.
>
> My question is:
>
> Can a bad thermostat causing a low coolant temperature cause the kinds of
> problems with the ignition I am decribing here? (Theroetically, the
coolant
> temperature switch doesn't get hot enough, maybe causing the ignition to
> deliver too hot of a spark all the time, causing it to die prematurely?)
>
> HELP!
>
>

 

I would definitely have to disagree with your coolant being a quart low
theory.

True that if coolant is low on some cars there might be no water availabe at
the appropriate temp sensors and the engine may be hotter than the guage
states. It is also true that coolant temperature is an input as to the
parameters in which an engine operates. HOWEVER this is not going to cause
a fuel injected vehicle to surge or run rough. It makes no sense. When you
start your vehicle and it is cold it certainly doesn't run rough or surge
and if it is hot it doesn't run rough or surge. The coolant sensors would
not cause a fuel injection system to operate outside it's programmed
parameters and cause driveability problems as you have described.

CaptainKrunch


"w_tom" <w_tom1@hotmail.com> wrote in message
news:3FE4C15E.315145C3@hotmail.com...
> Coolant a quart low will make temperature appear to be
> cooler as engine is overheating. Fuel injection system must
> know correct engine temperature to properly adjust fuel
> mixture. If engine temperature is hot and coolant appears
> cooler, then FI system has been observed to cause a cool
> engine to repeatedly surge and a warm engine to run rough -
> both while in idle. Why? FI system is only responding
> according to its inputs - because of a coolant shortage.
>
> How do you know engine is cool? Only from temp gauge on
> dash? Not good enough. What is the temperature of water by
> actually measuring inside radiator. A difference can exist
> between these two reading.
>
> Why, for gads sakes, were you wildly replacing the ignition
> module - and multiple times? If ignition module was bad, then
> simple test equipment would have made that obvious up front
> before wasting any money on new modules. If you don't
> specifically know what the problem is, then first get a
> responsible dealer or mechanic to, first, take some computer
> readings. Bottom line - it will cost less. And demand that
> printout so that you can also learn.
>
> Honda wrote:
> > I have a 1993 Honda Civic that recently started displaying some weird
> > ignition related problems.
> >
> > I noticed that sometimes the tach ocaissionally spikes during
> > operation. The car also started to run rough one day and proceeded
> > to get worse. I replaced the ignition module (the one in the
> > distributor) and it fixed the problem (temporarily). About a month
> > later, same thing (replaced another module). I have done this
> > several times.
> >
> > I noticed that the car is running cooler than usual, and suspect a
> > bad thermostat.
> >
> > My question is:
> >
> > Can a bad thermostat causing a low coolant temperature cause the
> > kinds of problems with the ignition I am decribing here?
> > Theroetically, the coolant temperature switch doesn't get hot
> > enough, maybe causing the ignition to deliver too hot of a spark
> > all the time, causing it to die prematurely?)
> >
> > HELP!

 

I would definitely have to disagree with your coolant being a quart low
theory.

True that if coolant is low on some cars there might be no water availabe at
the appropriate temp sensors and the engine may be hotter than the guage
states. It is also true that coolant temperature is an input as to the
parameters in which an engine operates. HOWEVER this is not going to cause
a fuel injected vehicle to surge or run rough. It makes no sense. When you
start your vehicle and it is cold it certainly doesn't run rough or surge
and if it is hot it doesn't run rough or surge. The coolant sensors would
not cause a fuel injection system to operate outside it's programmed
parameters and cause driveability problems as you have described.

CaptainKrunch


"w_tom" <w_tom1@hotmail.com> wrote in message
news:3FE4C15E.315145C3@hotmail.com...
> Coolant a quart low will make temperature appear to be
> cooler as engine is overheating. Fuel injection system must
> know correct engine temperature to properly adjust fuel
> mixture. If engine temperature is hot and coolant appears
> cooler, then FI system has been observed to cause a cool
> engine to repeatedly surge and a warm engine to run rough -
> both while in idle. Why? FI system is only responding
> according to its inputs - because of a coolant shortage.
>
> How do you know engine is cool? Only from temp gauge on
> dash? Not good enough. What is the temperature of water by
> actually measuring inside radiator. A difference can exist
> between these two reading.
>
> Why, for gads sakes, were you wildly replacing the ignition
> module - and multiple times? If ignition module was bad, then
> simple test equipment would have made that obvious up front
> before wasting any money on new modules. If you don't
> specifically know what the problem is, then first get a
> responsible dealer or mechanic to, first, take some computer
> readings. Bottom line - it will cost less. And demand that
> printout so that you can also learn.
>
> Honda wrote:
> > I have a 1993 Honda Civic that recently started displaying some weird
> > ignition related problems.
> >
> > I noticed that sometimes the tach ocaissionally spikes during
> > operation. The car also started to run rough one day and proceeded
> > to get worse. I replaced the ignition module (the one in the
> > distributor) and it fixed the problem (temporarily). About a month
> > later, same thing (replaced another module). I have done this
> > several times.
> >
> > I noticed that the car is running cooler than usual, and suspect a
> > bad thermostat.
> >
> > My question is:
> >
> > Can a bad thermostat causing a low coolant temperature cause the
> > kinds of problems with the ignition I am decribing here?
> > Theroetically, the coolant temperature switch doesn't get hot
> > enough, maybe causing the ignition to deliver too hot of a spark
> > all the time, causing it to die prematurely?)
> >
> > HELP!

 

I would definitely have to disagree with your coolant being a quart low
theory.

True that if coolant is low on some cars there might be no water availabe at
the appropriate temp sensors and the engine may be hotter than the guage
states. It is also true that coolant temperature is an input as to the
parameters in which an engine operates. HOWEVER this is not going to cause
a fuel injected vehicle to surge or run rough. It makes no sense. When you
start your vehicle and it is cold it certainly doesn't run rough or surge
and if it is hot it doesn't run rough or surge. The coolant sensors would
not cause a fuel injection system to operate outside it's programmed
parameters and cause driveability problems as you have described.

CaptainKrunch


"w_tom" <w_tom1@hotmail.com> wrote in message
news:3FE4C15E.315145C3@hotmail.com...
> Coolant a quart low will make temperature appear to be
> cooler as engine is overheating. Fuel injection system must
> know correct engine temperature to properly adjust fuel
> mixture. If engine temperature is hot and coolant appears
> cooler, then FI system has been observed to cause a cool
> engine to repeatedly surge and a warm engine to run rough -
> both while in idle. Why? FI system is only responding
> according to its inputs - because of a coolant shortage.
>
> How do you know engine is cool? Only from temp gauge on
> dash? Not good enough. What is the temperature of water by
> actually measuring inside radiator. A difference can exist
> between these two reading.
>
> Why, for gads sakes, were you wildly replacing the ignition
> module - and multiple times? If ignition module was bad, then
> simple test equipment would have made that obvious up front
> before wasting any money on new modules. If you don't
> specifically know what the problem is, then first get a
> responsible dealer or mechanic to, first, take some computer
> readings. Bottom line - it will cost less. And demand that
> printout so that you can also learn.
>
> Honda wrote:
> > I have a 1993 Honda Civic that recently started displaying some weird
> > ignition related problems.
> >
> > I noticed that sometimes the tach ocaissionally spikes during
> > operation. The car also started to run rough one day and proceeded
> > to get worse. I replaced the ignition module (the one in the
> > distributor) and it fixed the problem (temporarily). About a month
> > later, same thing (replaced another module). I have done this
> > several times.
> >
> > I noticed that the car is running cooler than usual, and suspect a
> > bad thermostat.
> >
> > My question is:
> >
> > Can a bad thermostat causing a low coolant temperature cause the
> > kinds of problems with the ignition I am decribing here?
> > Theroetically, the coolant temperature switch doesn't get hot
> > enough, maybe causing the ignition to deliver too hot of a spark
> > all the time, causing it to die prematurely?)
> >
> > HELP!

 

I would definitely have to disagree with your coolant being a quart low
theory.

True that if coolant is low on some cars there might be no water availabe at
the appropriate temp sensors and the engine may be hotter than the guage
states. It is also true that coolant temperature is an input as to the
parameters in which an engine operates. HOWEVER this is not going to cause
a fuel injected vehicle to surge or run rough. It makes no sense. When you
start your vehicle and it is cold it certainly doesn't run rough or surge
and if it is hot it doesn't run rough or surge. The coolant sensors would
not cause a fuel injection system to operate outside it's programmed
parameters and cause driveability problems as you have described.

CaptainKrunch


"w_tom" <w_tom1@hotmail.com> wrote in message
news:3FE4C15E.315145C3@hotmail.com...
> Coolant a quart low will make temperature appear to be
> cooler as engine is overheating. Fuel injection system must
> know correct engine temperature to properly adjust fuel
> mixture. If engine temperature is hot and coolant appears
> cooler, then FI system has been observed to cause a cool
> engine to repeatedly surge and a warm engine to run rough -
> both while in idle. Why? FI system is only responding
> according to its inputs - because of a coolant shortage.
>
> How do you know engine is cool? Only from temp gauge on
> dash? Not good enough. What is the temperature of water by
> actually measuring inside radiator. A difference can exist
> between these two reading.
>
> Why, for gads sakes, were you wildly replacing the ignition
> module - and multiple times? If ignition module was bad, then
> simple test equipment would have made that obvious up front
> before wasting any money on new modules. If you don't
> specifically know what the problem is, then first get a
> responsible dealer or mechanic to, first, take some computer
> readings. Bottom line - it will cost less. And demand that
> printout so that you can also learn.
>
> Honda wrote:
> > I have a 1993 Honda Civic that recently started displaying some weird
> > ignition related problems.
> >
> > I noticed that sometimes the tach ocaissionally spikes during
> > operation. The car also started to run rough one day and proceeded
> > to get worse. I replaced the ignition module (the one in the
> > distributor) and it fixed the problem (temporarily). About a month
> > later, same thing (replaced another module). I have done this
> > several times.
> >
> > I noticed that the car is running cooler than usual, and suspect a
> > bad thermostat.
> >
> > My question is:
> >
> > Can a bad thermostat causing a low coolant temperature cause the
> > kinds of problems with the ignition I am decribing here?
> > Theroetically, the coolant temperature switch doesn't get hot
> > enough, maybe causing the ignition to deliver too hot of a spark
> > all the time, causing it to die prematurely?)
> >
> > HELP!

 

CaptainKrunch wrote:
>
> I would definitely have to disagree with your coolant being a quart low
> theory.

I too will have to disagree on that.

>
> True that if coolant is low on some cars there might be no water availabe at
> the appropriate temp sensors and the engine may be hotter than the guage
> states.

Not even. The sensor for the gauge on that car is on the thermostat
housing, low down on the engine block, so you will have to be seriously
low on coolant before the sensor will get dry. If it does go dry and the
engine overheats, the sensor will get hot as well, and you most
certainly will se the temp gauge heading north. If you burst a hose and
loose all your coolant you definitely will want the gauge to show you
that the engine is overheating, and this is exactly what it does.

 

CaptainKrunch wrote:
>
> I would definitely have to disagree with your coolant being a quart low
> theory.

I too will have to disagree on that.

>
> True that if coolant is low on some cars there might be no water availabe at
> the appropriate temp sensors and the engine may be hotter than the guage
> states.

Not even. The sensor for the gauge on that car is on the thermostat
housing, low down on the engine block, so you will have to be seriously
low on coolant before the sensor will get dry. If it does go dry and the
engine overheats, the sensor will get hot as well, and you most
certainly will se the temp gauge heading north. If you burst a hose and
loose all your coolant you definitely will want the gauge to show you
that the engine is overheating, and this is exactly what it does.

 

CaptainKrunch wrote:
>
> I would definitely have to disagree with your coolant being a quart low
> theory.

I too will have to disagree on that.

>
> True that if coolant is low on some cars there might be no water availabe at
> the appropriate temp sensors and the engine may be hotter than the guage
> states.

Not even. The sensor for the gauge on that car is on the thermostat
housing, low down on the engine block, so you will have to be seriously
low on coolant before the sensor will get dry. If it does go dry and the
engine overheats, the sensor will get hot as well, and you most
certainly will se the temp gauge heading north. If you burst a hose and
loose all your coolant you definitely will want the gauge to show you
that the engine is overheating, and this is exactly what it does.

 

CaptainKrunch wrote:
>
> I would definitely have to disagree with your coolant being a quart low
> theory.

I too will have to disagree on that.

>
> True that if coolant is low on some cars there might be no water availabe at
> the appropriate temp sensors and the engine may be hotter than the guage
> states.

Not even. The sensor for the gauge on that car is on the thermostat
housing, low down on the engine block, so you will have to be seriously
low on coolant before the sensor will get dry. If it does go dry and the
engine overheats, the sensor will get hot as well, and you most
certainly will se the temp gauge heading north. If you burst a hose and
loose all your coolant you definitely will want the gauge to show you
that the engine is overheating, and this is exactly what it does.

 

It is just that only hours before, we solved the exact same
problem on a Toyota. We had just put one quart of coolant
into the Toyota whose sensors said the engine was running cool
- but the water in radiator was boiling - bubbling hot.
Refilling the cooling system solved a surging and unstable
idle, and increased heat to the heater core.

FI system needs the exact engine temperature to provide
proper operation. With low coolant, the FI system was not
functioning properly causing surging when cool and unstable
operation when engine was 'long term operation' warm.

Its only a theory for the Civic. It was reality for the
Toyota.

BTW, all Hondas have a bleed valve at top of engine so that
air pocket does not remain inside engine. If coolant is low,
then the air pocket should be bled at this valve.

CaptainKrunch wrote:
> I would definitely have to disagree with your coolant being a quart
> low theory.
>
> True that if coolant is low on some cars there might be no water availabe at
> the appropriate temp sensors and the engine may be hotter than the guage
> states. It is also true that coolant temperature is an input as to the
> parameters in which an engine operates. HOWEVER this is not going to cause
> a fuel injected vehicle to surge or run rough. It makes no sense. When you
> start your vehicle and it is cold it certainly doesn't run rough or surge
> and if it is hot it doesn't run rough or surge. The coolant sensors would
> not cause a fuel injection system to operate outside it's programmed
> parameters and cause driveability problems as you have described.
>
> CaptainKrunch

 

It is just that only hours before, we solved the exact same
problem on a Toyota. We had just put one quart of coolant
into the Toyota whose sensors said the engine was running cool
- but the water in radiator was boiling - bubbling hot.
Refilling the cooling system solved a surging and unstable
idle, and increased heat to the heater core.

FI system needs the exact engine temperature to provide
proper operation. With low coolant, the FI system was not
functioning properly causing surging when cool and unstable
operation when engine was 'long term operation' warm.

Its only a theory for the Civic. It was reality for the
Toyota.

BTW, all Hondas have a bleed valve at top of engine so that
air pocket does not remain inside engine. If coolant is low,
then the air pocket should be bled at this valve.

CaptainKrunch wrote:
> I would definitely have to disagree with your coolant being a quart
> low theory.
>
> True that if coolant is low on some cars there might be no water availabe at
> the appropriate temp sensors and the engine may be hotter than the guage
> states. It is also true that coolant temperature is an input as to the
> parameters in which an engine operates. HOWEVER this is not going to cause
> a fuel injected vehicle to surge or run rough. It makes no sense. When you
> start your vehicle and it is cold it certainly doesn't run rough or surge
> and if it is hot it doesn't run rough or surge. The coolant sensors would
> not cause a fuel injection system to operate outside it's programmed
> parameters and cause driveability problems as you have described.
>
> CaptainKrunch

 

It is just that only hours before, we solved the exact same
problem on a Toyota. We had just put one quart of coolant
into the Toyota whose sensors said the engine was running cool
- but the water in radiator was boiling - bubbling hot.
Refilling the cooling system solved a surging and unstable
idle, and increased heat to the heater core.

FI system needs the exact engine temperature to provide
proper operation. With low coolant, the FI system was not
functioning properly causing surging when cool and unstable
operation when engine was 'long term operation' warm.

Its only a theory for the Civic. It was reality for the
Toyota.

BTW, all Hondas have a bleed valve at top of engine so that
air pocket does not remain inside engine. If coolant is low,
then the air pocket should be bled at this valve.

CaptainKrunch wrote:
> I would definitely have to disagree with your coolant being a quart
> low theory.
>
> True that if coolant is low on some cars there might be no water availabe at
> the appropriate temp sensors and the engine may be hotter than the guage
> states. It is also true that coolant temperature is an input as to the
> parameters in which an engine operates. HOWEVER this is not going to cause
> a fuel injected vehicle to surge or run rough. It makes no sense. When you
> start your vehicle and it is cold it certainly doesn't run rough or surge
> and if it is hot it doesn't run rough or surge. The coolant sensors would
> not cause a fuel injection system to operate outside it's programmed
> parameters and cause driveability problems as you have described.
>
> CaptainKrunch

 

It is just that only hours before, we solved the exact same
problem on a Toyota. We had just put one quart of coolant
into the Toyota whose sensors said the engine was running cool
- but the water in radiator was boiling - bubbling hot.
Refilling the cooling system solved a surging and unstable
idle, and increased heat to the heater core.

FI system needs the exact engine temperature to provide
proper operation. With low coolant, the FI system was not
functioning properly causing surging when cool and unstable
operation when engine was 'long term operation' warm.

Its only a theory for the Civic. It was reality for the
Toyota.

BTW, all Hondas have a bleed valve at top of engine so that
air pocket does not remain inside engine. If coolant is low,
then the air pocket should be bled at this valve.

CaptainKrunch wrote:
> I would definitely have to disagree with your coolant being a quart
> low theory.
>
> True that if coolant is low on some cars there might be no water availabe at
> the appropriate temp sensors and the engine may be hotter than the guage
> states. It is also true that coolant temperature is an input as to the
> parameters in which an engine operates. HOWEVER this is not going to cause
> a fuel injected vehicle to surge or run rough. It makes no sense. When you
> start your vehicle and it is cold it certainly doesn't run rough or surge
> and if it is hot it doesn't run rough or surge. The coolant sensors would
> not cause a fuel injection system to operate outside it's programmed
> parameters and cause driveability problems as you have described.
>
> CaptainKrunch