Engine/Transmission (1998.5 - 2002) pyro

[Tractorat]

Is this normal ? I dont normally ever take a look at my pyro guage unless Im pulling my trailer, or maybe going up a steep hill



This morning I was driving down the freeway (unloaded) at about 60mph in overdrive. The grade was going downhill, but not exactly steep. I just happened to notice that my pyro gauge was reading about 200 degrees, and then dropped even below that. Is that normal ? I put on the 4" exhaust last year, and really havent driven it a lot since I did that. It probably does that all of the time, but Ive just never noticed.



When the road leveled out, it did come back to read 400d, and then up from there as the road began to climb. Other than that, it seems normal to me.

 

[klcammie]

I've seen 300 on a down hill while unloaded. never below that while running freeway speed. Where is pryo located before of after tubro? there is about a 300 dr difference.

 

[JR]

Even at an idle my egt gauge will rarely register below 275 unless it is very cold out. (Below zero) On a flat level stretch of road at 60mph I will see in the neighborhood of 550 - 600*

 

[cerberusiam]

Quite likely normal. If your foot or CC lifted off the throttel to keep speed down it probably zeroed the APPS. At that point you have idle fuel in an engine pump air for 1200-1300 rpms, not much heat goign to be generated at that point.

 

[Tractorat]

Thanks for the feedback. I suspected as such. And as I said, the only time Ive really looked at the pyro was when the truck was working harder.
I was surprised though, that it would go down so low. I didnt expect that.

 

[Cosmo]

That 300 degree thing is not accurate.

I moved my pyro from after to before and the EGTs went up about 100-150 at cruise, but WOT I went from seeing no higher than about 1200 degrees to over 1700.

 

[Tractorat]

I finally called the place the installed the gauges in the first place. He told me the wires on the back of the gauge could have come loose in the 2 years since I had them installed. So, I pulled the gauge out and "tightened" the wire terminals. I didn't think I really moved the nut at all. (he said to be gentle so as not to damage the gauge). But, when I put it back and went for a test drive, everything is back to normal.

 

[klcammie]

I know. the 300 degre is an estimate that is why I said ABOUT 300. Hey Tractorat glad to hear the problem was simple and is now fixed.

 

[Shelby Griggs]

I have mine pre turbo in the exhaust manifold, run as low as 200'ish on a long downgrade and about 600 or so on the flat, 60 MPH and no headwind. I believe Mr. Cummins once said 600 was most efficient at least back in the day when they were doing lots of testing, that does seem to give good mileage if I keep it around 600 degrees. I am running a digital SPA gauge, pretty responsive and has a resolution of 7 degrees. I drop a gear when I hit 1000 degrees pulling a grade, all has been good for 1/4 million miles.