Turbo miata showing hot temperatures

My miata has started to run hot according to the temp gauge, which is
not too surprising considering that we are already hitting close to 100
degrees. The car has a turbo running 9 pounds of boost, a large
intercooler, and has no accessories like A/C or power steering. The temp
gauge has been linearized (if someone could give a quick explanation of
what exactly this means I would appreciate it).

Anyway, the gauge goes up, but not past the water mark on the high end,
and will actually get cooler sometimes when I apply boost. I used a
friends red dot thermometer while the car's gauge was showing hot, and
everything was running pretty cool from the engine to the headers to the
intercooler, turbo, radiator, etc. The car also seems to be running
identically to the way it was before the gauge started reading high, and
the TEC-3 computer is showing no codes to indicate anything is wrong.
My first guess is a faulty gauge, but the fact that it is running
hotter just as the temperatures are soaring seems to be too much of a
coincidence. The car also has an exhaust temp. gauge that is showing
normal readings.

I need to do some research on the power list, but I was hoping someone
could offer some quick suggestions as to where to start. I was thinking
about checking the gauge first, replacing the thermostat and/or trying
to increase airflow into the engine compartment.
If anyone has a link to an aftermarket temp gauge that shows numbers
that will replace the stock gauge in the same location, that would be
great as well.

Thanks!

Pat

Here are some of the engine details if it matters:

'94 1.8L bottom end (8.8:1 compression)
'99 head & intake manifold
ARP head studs
ACT Extreme clutch
Flyin' Miata/Fidanza lighthweight flywheel
'99 Torsen differential (4.3:1), '00 axles & driveshaft
Flyin' Miata aluminum radiator
Coolant reroute to exit at rear of head
Mazdaspeed motor mounts
Linearized temp gauge, tach modified for quicker response
No AC, no PS

Tec3 ECU with latest software running full sequential
Momo steering wheel
5 point harnesses in addition to factory belts
CD player & headrest speakers
Boost (in eyeball vent) & EGT (below stereo) gauges

Garrett ball bearing GT2871R turbo w/ ATP turbo T3 .86 A/R exhaust housing
Tial 40mm external wastegate w/ .4 bar spring
ETD Racing "shorty" turbo header
Custom downpipe by Corky Bell w/ flex sections & wastegate joined in at Cat
Racing Mazda 3" high flow cat, bolt-in
Enthuza Racing 3" single outlet turbo exhaust
18"x8"x3" bar & plate intercooler from Bell Intercoolers
Silicone hose couplings, T-bolt clamps
Vishnu dual feed fuel rail
RC 550cc/min injectors

Quick check: is your front license plate mounted right in front of the
air-intake? That was my problem. When the ambient air temperature got above
about 30 Celsius the engine started running hot. I tried everything -
changing the thermostat and even the rad etc etc. It turned out to be the
restricted air-intake because of the position of the license plate (why on
earth did they put it right in front of the air-intake?!)

Moving the plate onto the nose using
http://www.mx5parts.co.uk/product_in...roducts_id/222 finally solved
the problem.

Eric

Eric Baber wrote:
> Quick check: is your front license plate mounted right in front of the
> air-intake? That was my problem. When the ambient air temperature got above
> about 30 Celsius the engine started running hot. I tried everything -
> changing the thermostat and even the rad etc etc. It turned out to be the
> restricted air-intake because of the position of the license plate (why on
> earth did they put it right in front of the air-intake?!)
>
> Moving the plate onto the nose using
> http://www.mx5parts.co.uk/product_in...roducts_id/222 finally solved
> the problem.
>
> Eric
>
>

Hi Eric,
there is no front license plate on this car most of the time.
We are supposed to have one installed in Texas, but I have been
driving here in Austin, TX for 20 years and have never been pulled over
for no front license plate by local police.
The highway patrol has enforced it on me, though with a warning each
time, so I usually put it back on when taking trips out of town,
especially to South Texas.

pat

pws > wrote:

>My miata has started to run hot according to the temp gauge, which is
>not too surprising considering that we are already hitting close to 100
>degrees.

Maybe crap build up in de cooling circuit? Mine was running hot,
but after de coolant burst through the heater hose, it is actually
running cool. I guess the burst blew some of the crap out.

> The car has a turbo running 9 pounds of boost, a large
>intercooler, and has no accessories like A/C or power steering. The temp
>gauge has been linearized (if someone could give a quick explanation of
>what exactly this means I would appreciate it).

I can offer a pretty good guess. As discussed before, the Miata
temp gauge is sitting in the center position from when the coolant
is luke warm until just before the steam pressure blows up the
engine. That is called a nonlinear response. I would assume a
linearized gauge is one that shows the *true* temperature.

>Anyway, the gauge goes up, but not past the water mark on the high end,
>and will actually get cooler sometimes when I apply boost. I used a
>friends red dot thermometer while the car's gauge was showing hot, and
>everything was running pretty cool from the engine to the headers to the
>intercooler, turbo, radiator, etc. The car also seems to be running
>identically to the way it was before the gauge started reading high, and
>the TEC-3 computer is showing no codes to indicate anything is wrong.

I would think that the Tec is right. You are just seeing the *true*
temperatures for the first time.

Then again, I could be wrong and you buy a new engine.

> My first guess is a faulty gauge, but the fact that it is running
>hotter just as the temperatures are soaring seems to be too much of a
>coincidence. The car also has an exhaust temp. gauge that is showing
>normal readings.

Not related.

>I need to do some research on the power list, but I was hoping someone
>could offer some quick suggestions as to where to start. I was thinking
>about checking the gauge first, replacing the thermostat and/or trying
>to increase airflow into the engine compartment.
>If anyone has a link to an aftermarket temp gauge that shows numbers
>that will replace the stock gauge in the same location, that would be
>great as well.

That is of course the way to go. But if I knew one, it would probably
already be on my car. (Assuming it looks the same as OEM.)

Leon

--
Leon van Dommelen Bozo, the White 96 Sebring Miata .)
REMOVE THE "z"s -> www.dommelen.net

"EXIT THE INTERSTATES" (Jamie Jensen)

Leon van Dommelen wrote:

> I would think that the Tec is right. You are just seeing the *true*
> temperatures for the first time.
>
> Then again, I could be wrong and you buy a new engine.

Come on Leon, when have you, (or a computer), ever been wrong? ;-)


> That is of course the way to go. But if I knew one, it would probably
> already be on my car. (Assuming it looks the same as OEM.)
>
> Leon

It seems like VDO, Autometer, or one of the other gauge companies would
see a big enough market for an OEM-look replacement temp gauge with
numbers for the miata since there are so many enthusiasts out there.
However, like you, I have never seen one. I would definitely pay $50.00
to $100.00 for one if it becomes available.

Thanks Leon, I'll check the cooling circuit and thermostat first.

Pat

>>I need to do some research on the power list, but I was hoping someone
>>could offer some quick suggestions as to where to start. I was thinking
>>about checking the gauge first, replacing the thermostat and/or trying
>>to increase airflow into the engine compartment.
>>If anyone has a link to an aftermarket temp gauge that shows numbers
>>that will replace the stock gauge in the same location, that would be
>>great as well.

Not a gauge, but Davis Instrument manufactures a gizmo (Carchip E/X)
that plugs into the car's ODB II port and records trip data and up to
four engine parameters (if the vehicle is ODB II compliant, like a
stock Miata is)

You can download trip data for analysis on any PC. It is a trip and
driver monitor, so use with caution unless you want to find out if
your significant other is driving around with the rev limiter pegged.

Only complaint I have about it is that I can't put back the dash cove
unless you cut finger recess molding on it, that that hole is mostly
invisible anyway.

You can pick one up at Autozone or Sears, and of course, Ebay.

M. Cantera wrote:

>
> Not a gauge, but Davis Instrument manufactures a gizmo (Carchip E/X)
> that plugs into the car's ODB II port and records trip data and up to
> four engine parameters (if the vehicle is ODB II compliant, like a
> stock Miata is)
>
> You can download trip data for analysis on any PC. It is a trip and
> driver monitor, so use with caution unless you want to find out if
> your significant other is driving around with the rev limiter pegged.
>
> Only complaint I have about it is that I can't put back the dash cove
> unless you cut finger recess molding on it, that that hole is mostly
> invisible anyway.
>
> You can pick one up at Autozone or Sears, and of course, Ebay.


This is a heavily modified miata with a Tec-3 engine management system.
I haven't looked at all of the features it has yet, but it probably
monitors top speeds and that sort of thing, it seems to do everything
else from adjusting the turbo boost levels, the timing, the air/fuel
mixture, fuel flow per injector, etc, etc., all from a laptop showing
the engine working in real time using a dashboard gauge layout, it is
really very cool.
You can have the passenger make adjustments to the timing as you drive
to see the immediate effects, something that is obviously impossible
with the stock setup.
There is no more factory rev limiter, you use the computer to set it
anywhere from way below the miata's stock max rpm all the way up to
20,000 rpm, though I believe that I would have a smoking ruin of an
engine long before then. ;-) I have it set at 7500 rpm max right now.

No significant other to worry about right now, my miata's babe magnet
seems to be malfunctioning. I'll have it checked out next week. :-)

Pat

I've glanced at the specs of that unit not too long ago (user's manual
mostly) I do remenber this: That unit allows you to map and modify the
engine behavior (or screw it up royally) using a laptop on the fly.
Back to the original topic about running hot: I do remeber the
trigger points of the cooling fan are settable (to do this it has to
monitor the coolant temperature, that is a standard ODB II parameter).
and the user's manual has a table of the datastream (i.e. the byte
order for a scan cycle and what they are, so you can monitor anything
that is hooked up to the control unit) with a reference to outputinig
the data to other applications, such as a spreadsheed. it may require
some figuring out, but you should be able to get listing of whatever
your engine is doing (it many help if you know any control systems
engineers)

I did not see any refences to connecting a windows CE or Palm Pilot
device as a handheld monitoring and logging device though I thing that
would be very usefull for monitoring operating conditions.

Good luck




On Tue, 21 Jun 2005 04:27:31 GMT, pws > wrote:

>
>This is a heavily modified miata with a Tec-3 engine management system.
>I haven't looked at all of the features it has yet, but it probably
>monitors top speeds and that sort of thing, it seems to do everything
>else from adjusting the turbo boost levels, the timing, the air/fuel
>mixture, fuel flow per injector, etc, etc., all from a laptop showing
>the engine working in real time using a dashboard gauge layout, it is
>really very cool.
>You can have the passenger make adjustments to the timing as you drive
>to see the immediate effects, something that is obviously impossible
>with the stock setup.
>There is no more factory rev limiter, you use the computer to set it
>anywhere from way below the miata's stock max rpm all the way up to
>20,000 rpm, though I believe that I would have a smoking ruin of an
>engine long before then. ;-) I have it set at 7500 rpm max right now.
>
>No significant other to worry about right now, my miata's babe magnet
>seems to be malfunctioning. I'll have it checked out next week. :-)
>
>Pat

pws > wrote:

>M. Cantera wrote:
>
>>
>> Not a gauge, but Davis Instrument manufactures a gizmo (Carchip E/X)
>> that plugs into the car's ODB II port and records trip data and up to
>> four engine parameters (if the vehicle is ODB II compliant, like a
>> stock Miata is)
>>
>> You can download trip data for analysis on any PC. It is a trip and
>> driver monitor, so use with caution unless you want to find out if
>> your significant other is driving around with the rev limiter pegged.
>>
>> Only complaint I have about it is that I can't put back the dash cove
>> unless you cut finger recess molding on it, that that hole is mostly
>> invisible anyway.
>>
>> You can pick one up at Autozone or Sears, and of course, Ebay.
>
>
>This is a heavily modified miata with a Tec-3 engine management system.
>I haven't looked at all of the features it has yet, but it probably
>monitors top speeds and that sort of thing, it seems to do everything
>else from adjusting the turbo boost levels, the timing, the air/fuel
>mixture, fuel flow per injector, etc, etc., all from a laptop showing
>the engine working in real time using a dashboard gauge layout, it is
>really very cool.

If it like my Link ECU, it also outputs coolant temperature.

Leon

>You can have the passenger make adjustments to the timing as you drive
>to see the immediate effects, something that is obviously impossible
>with the stock setup.
>There is no more factory rev limiter, you use the computer to set it
>anywhere from way below the miata's stock max rpm all the way up to
>20,000 rpm, though I believe that I would have a smoking ruin of an
>engine long before then. ;-) I have it set at 7500 rpm max right now.
>
>No significant other to worry about right now, my miata's babe magnet
>seems to be malfunctioning. I'll have it checked out next week. :-)
>
>Pat

--
Leon van Dommelen Bozo, the White 96 Sebring Miata .)
http://www.dommelen.net/miata
EXIT THE INTERSTATES (Jamie Jensen)

Leon van Dommelen wrote:

>
> If it like my Link ECU, it also outputs coolant temperature.
>
> Leon
>

I haven't had as much time to check it out as I would like, but I should
have time to look at it soon and learn some more about it.

As a test, I took out the driver's side turn signal and noticed
immediate cooling improvement (according to the gauge) once I reached
speed. It is still creeping up at stop lights, but not dangerously so,
and I have a feeling that, as you said, I am simply seeing a true
reading of the temp since the gauge is now "linearized" (without
numbers, grrrr....), and it makes sense for it to go up some during a
stop in this extremely hot weather even with the fans working properly.

Just as a side note on the temp gauge, my friend's GMC pickup has a
gauge that shows actual numbers and registers hotter or cooler according
to temperature, so I am assuming it is linearized instead of an idiot
gauge. I guess neither Mazda nor the aftermarket auto gauge companies
can manage to accomplish such a feat for us.

Pat