Low temps are not bad at all, I do not think that is the concern. I think the bigger concern is the accuracy at the lower temp readings. For example if you are wanting to let your turbo cool for a few minutes but, your gauge automatically drops to 150 degrees then you have no base to how much it really cooled off. I would be highly suprised if your temps should ever be less than about 225-250 degrees at idle and it would have to be cool outside to do that once the engine is warm. On startup it does take a second for the temp to come up but, once it is there it should not just fall to 150 deg.


Also heat and radiation can affect the thermocouple but, it would be very slight if any at all. I have played with them in a lot of ways and the heat and noise under the hood should not have any affect that you will ever notice.

 

They all have an amplifier or amplified circuitry. Trust me some are internal and some are external boxes like isspro but, they all have them. If they do not somehow then I do not see how they could even be reasonably accurate.

 

You are totally wrong.
I've installed dozens of pyros over the last thirty years until more recently none required any outside power thus no amp.
All the pyro gauge is a millivolt meter, the thermocouple a voltage generator whose voltage changes with temperature. The reason some of the "modern" pyros use an amp is so they can get away with a cheap gauge. The non-amplified gauges use a high quality gauge. The non-amplified gauges are 'on' all the time. With my non-amplified pyros I can even read the outside ambient temperature with just the gauge and thermocouple sitting on a rock.

 

make sure you didn't ground the pyro with the gauge wiring they need tobe grounded seperate.

 

Trudt me, the may not have an amplifier "chip" but, they have amplifier circuitry. I have taken apart plnety of gauges as well as worked with Stewart Warner and Autometer and plenty of other manufacturers when we started building them.

They do not need power because the filtered mV signal drives the stepper motor or whatever they are using to run the needle. So you are right they do not need additional power but, they are filtering/amplifying the signal or they will not be accurate.

Also remember with analog the best they are going to show you is in about 25deg resolution and most of them are not that good. So they do not have to be that spot on to work as they advertise them.

 

Sorry gzilla but what you describe, amplifying without additional power defies the laws of physics.
You're talking about a perpetual motion machine.

 

Wait, what about my truck?? "The Perpetual Motion Machine"

 

How far is the probe into the exhuast manifold ? Should be about an inch if I remember right.

 

I'm gonna go make some popcorn

 

I was gonna say something like that, but I figured the poor guy needs to figure out why his EGT's are reading low.

 

I already told you, your gauge is broken, send it back.

 

UPDATE: So I assume that everything is fine now. My gauge DOES have its own power and ground for the stepper motor. I ran new power/ground wires directly from the battery. Someone said that you shouldn’t ground the pyrometer with the ground for the lights. I don’t see how this could cause a problem because a ground is a ground is a ground, but I ran a new one from the battery to take that out of the possible problem. Anyway, I think my problem may have stemmed from not using the supplied inline fuse. When I hooked up the power wire originally, I just tapped into a constant power source that was already on a fuse. I assume, after hearing/reading that the gauge works off differential in resistances, that the supplied inline fuse provides a certain specific resistance. This resistance would be different when using a different fuse. So now the truck runs at what I assume to be normal, unloaded temperatures. At a stop light it will drop to around 275-300 if sitting there for more then 30 seconds. This sounds right to me as the manual says to let it idle for ~1 minute if running around unloaded.