Help!! (from the north country)

"Andrew Stephenson" <ames@deltrak.demon.co.uk> wrote in message
news:1165689891snz@deltrak.demon.co.uk...[color=blue]
> In article <d3fdd$457af3d6$47c2b532$14646@msgid.meganewsservers.com>
> rokigawaATtristarassociatesDOTcom "Ray O" writes:
>[color=green]
>> The other thing that has me puzzled is the nature of the knock
>> sensor. Toyota uses a piezo-electric crystal inside the knock
>> sensor, and the crystal is struck or twisted, a static spark is
>> emitted. I don't know much about those crystals, but I can't
>> imagine how they can send a signal without a physical force,
>> i.e., knocking, exerted on them. [...][/color]
>
> AFAIK, you are correct. The mechanical energy of deformation
> becomes electrical energy. No change in deformation, no spark.
>
> Possible useful data: IIRC, the source impedance of the piezo/e
> crystal is very high. A large serial resistance could probably
> be tolerated (guess: several tens of kilo-ohms); but it wouldn't
> take much shunt leakage (ie, across the wires carrying the pulse
> away) for the pulse to be crippled. Think of a battery with high
> internal resistance -- but _really_ high.
>
> Excessive shunt capacitance would also slug the pulse -- though I
> don't see how anyone could _accidentally_ introduce that into an
> established design. OTOH, if there were significant extra serial
> resistance, such from a manky connection, less shunt capacitance
> could slug the pulse. Shunt capacitance could be caused by using
> a non-standard cable, especially screened and excessively long.
> NB: This paragraph is speculative; it may also contain nuts.
> --
> Andrew Stephenson
>[/color]

This info seems to make it even less likely that the bad knock sensor would
make the ECM retard timing. In other words, a bad knock sensor is more
likely to keep timing too advanced, not too retarded.
--

Ray O
(correct punctuation to reply)

Ray O wrote:[color=blue]
> "googleisfun" <thecarpenter333@yahoo.com> wrote in message
> news:1165579991.839138.273590@80g2000cwy.googlegroups.com...[color=green]
> > Help, my 1995 Corolla has a very weak heating system. I am freezing
> > driving to work up in the north country. What are the potential reasons
> > for this "lukewarm" heater? Any regular maintenance for heaters?
> >[/color]
>
> There are 2 probable causes for insufficient heater output.
>
> If the engine coolant temperature gauge on the instrument panel reads cold,
> then the thermostat is probably stuck in the open position and a replacement
> thermostat will probably fix the problem. If the coolant is more than 2
> years old, have it replaced while changing the thermostat.
> Yes, the temp gauge never moves from cold...unless the car is idle and then the needle will move up. But always reads cold when driving. The coolant is about two years old, also, but the temp gauge read cold even after new coolant was put in.
> Another potential cause is a heater control valve that is stuck in the
> closed or partially closed position, especially if the engine coolant is
> reaching normal operating temperature. The heater control valve is located
> on the firewall. If you are not familiar with what it looks like, the
> easiest way to find it is to have someone inside move the temperature
> control back and forth from cold to hot while you look at the connections
> for the hoses about the same diameter as a garden hose on the firewall
> between the engine and passenger compartments. You should see a metal cable
> moving a lever about 2 inches long. The cable/lever is attached to the
> heater control valve, and that allows hot coolant to pass through to the
> heater core. If the cable is detached from the lever or the cable does not
> move the lever, then there is a problem with the controls. You can try
> manually moving the lever one way or the other to see if the heater works.
> By the way, it is not necessary to have the engine running while you look
> for the heater control valve, and it is probably safer if it is not running.
>
> Good luck!
> -- Thanks I will see if I can find this on the firewall, try to move it around to see if it is stuck or something
>
> Ray O
> (correct punctuation to reply)[/color]

"googleisfun" <thecarpenter333@yahoo.com> wrote in message
news:1165716010.774302.245560@j72g2000cwa.googlegroups.com...[color=blue]
>
> Ray O wrote:[color=green]
>> "googleisfun" <thecarpenter333@yahoo.com> wrote in message
>> news:1165579991.839138.273590@80g2000cwy.googlegroups.com...[color=darkred]
>> > Help, my 1995 Corolla has a very weak heating system. I am freezing
>> > driving to work up in the north country. What are the potential reasons
>> > for this "lukewarm" heater? Any regular maintenance for heaters?
>> >[/color]
>>
>> There are 2 probable causes for insufficient heater output.
>>
>> If the engine coolant temperature gauge on the instrument panel reads
>> cold,
>> then the thermostat is probably stuck in the open position and a
>> replacement
>> thermostat will probably fix the problem. If the coolant is more than 2
>> years old, have it replaced while changing the thermostat.[/color][/color]
[color=blue][color=green]
>> Yes, the temp gauge never moves from cold...unless the car is idle and
>> then the needle will move up. But always reads cold when driving. The
>> coolant is about two years old, also, but the temp gauge read cold even
>> after new coolant was put in.[/color][/color]

If the temp gauge reads cold and there is no heat from the heater, then the
most likely cause is a thermostat stuck in the open position. If you do the
repair yourself, get enough new coolant for the capacity of your cooling
system, a new thermostat, and a new thermostat housing. Take the old
coolant to an appropriate recycling or waste disposal facility. Carefully
clean the surfaces where the old gasket was with a gasket scraper or razor
blade, being careful to avoid gouging the aluminum housing. Orient the new
thermostat exactly the same way as the old one, with the spring facing down
and the jiggler valve oriented the same way as the old one. With the heater
control in the full hot position, re-fill the radiator, leave the cap off,
and start the engine. Watch the coolant level in the radiator, and as it
drops, slowly top it off until it does not drop any more. Replace the
radiator cap and fill the coolant overflow bottle to the hot mark. Watch
the overflow bottle over the next few days and top off as needed.

If you elect to have someone do the work for you, ask for the old thermostat
so you can see what it looks like when it is stuck open.
[color=blue][color=green]
>> Another potential cause is a heater control valve that is stuck in the
>> closed or partially closed position, especially if the engine coolant is
>> reaching normal operating temperature. The heater control valve is
>> located
>> on the firewall. If you are not familiar with what it looks like, the
>> easiest way to find it is to have someone inside move the temperature
>> control back and forth from cold to hot while you look at the connections
>> for the hoses about the same diameter as a garden hose on the firewall
>> between the engine and passenger compartments. You should see a metal
>> cable
>> moving a lever about 2 inches long. The cable/lever is attached to the
>> heater control valve, and that allows hot coolant to pass through to the
>> heater core. If the cable is detached from the lever or the cable does
>> not
>> move the lever, then there is a problem with the controls. You can try
>> manually moving the lever one way or the other to see if the heater
>> works.
>> By the way, it is not necessary to have the engine running while you look
>> for the heater control valve, and it is probably safer if it is not
>> running.
>>
>> Good luck!
>> -- Thanks I will see if I can find this on the firewall, try to move it
>> around to see if it is stuck or something
>>
>> Ray O
>> (correct punctuation to reply)[/color][/color]

It sounds more like the thermostat is stuck open.

Good luck!
--

Ray O
(correct punctuation to reply)