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Jon,
I think we are at the same spot except for the part where EGT is higher from compressed air rather than from combustion. I don't think this is thermodynamically possible.
http://static.howstuffworks.com/gif/...two-stroke.gif
If this is the illustration of the power stroke and allowing for expansion of the gas of combustion vs the same thing happening less the fuel and said gas, the heat generated by combustion is obviously higher than that of compression (although the air is heated past the auto-ignition temperature of the fuel). I just don't understand why the heat would be higher rather than lower?
And I am not trying to be a pain in the Lew, it just intuitively doesn't seem that way (to me). But I reserve the right to be wrong. :)
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JDUB,
It relates to the volume of gases entering the exhaust manifold.
I presume you accept the fact that at idle, there is no temperature registered on the pyros.
Because you posted it earlier the jake when employed causes the virtual cessation of fuel flow.
So from the above we know an idling engine will not have an exhaust gas flow sufficiently hot in a volume necessary to register on the pyros, but we know an engine at higher RPM, without combustion (none can take place with the jake engaged) will register, and therefore the temperature rise can only be attributed to the heat of compression.
Now can we agree?
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Well almost. I am saying that there is enough temperature to register when idling, it is most likely that the pyro is showing it and nobody notices it or that the pyro lacks sufficient resolution to account for it properly.
But what I am saying is that if you were going down a hill with the Jake brake off, the EGT would be higher than with the Jake brake operating. If I were not 8 hours in any direction from a decent hill I would test it and note the temps but we can table the discussion until Santa Fe and resume with empirical data.
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Old timer's disease at work here.
My pyros, with the jake off and my foot off the gas pedal, coasting down a hill, would drop to the bottom of the scale.
Same situation, but with the jake on the low setting, one needle would be down the bottom of the scale and the pyro on the side the jake was functioning would be up around 300 (if my brain isn't yet fried from all the bling I am installing).
What am I missing in your understanding of this?
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Well, to end the thread sorta where it started, I am now officially on my first trip. I'm in Salt Lake City at KOA (nice place), but definately had no jake brake at all. Had a few good downhills from CA through Utah, but would slow to about 40, downshift to 3rd, and that would hold couple of fairly steep downgrades.
Definately don't want to do this forever. The tech at Country Coach last week indicated they could wire the jake to bypass the CC control boards, and I think I'm going to call them tomorrow about that.
They cannot see me up in Oregon until September, if I make an appointment right now. I even spoke with the bus-conversion service manager, but he wouldn't/couldn't get me in earlier. He did indicate if I got the control boards up to him that they would repair them in a matter of a few days.
Unfortunately, I'm not sure whether or not things are actually worse on the coach, after Prevost attempted to fix the air conditioner and jake issue. Several things which used to work are no longer functional, and a couple of things seem magically healed.
I still haven't called the people mentioned earlier in the thread, but may do so tomorrow. Main energy was getting here in open piece. Wife is taking training this week while I stay in the bus, and work remotely.
Anyway, the bus ran great and got here smoothly, and in the end result, that's what I was hoping for. I'll get these control board issues figured out with time.
Ray
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Ray,
I know how exciting that first trip is - congratulations. Hopefully you'll get the rest of the bugs out and put this behind you and add many miles down the road.
Mike
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Ray, Sorry I'm so slow on the response. I just located my two spare cards for our 93 CC. One is a "dimmer card" used in the lighting circuits and the other is a controller for the locks and lights. No help to you.
Some of your strange happenings may be caused by dirty contacts on the card sockets or the cables on the rear of the panel that the cards plug into. On ours, there are numerous large mollex style connectors just overhead the panel (which will swing out for access to the rear, if you haven't done that yet) and I've had to pull some of these connectors apart, clean them and push them back together. I've pulled all of the cards and cleaned the sockets they seat in as my "electronics compartment" as I call it was pretty dusty. Locate a good quality electrical contact cleaner that is safe for all plastics and pull each card (suggest you power down the coach first) and clean the socket and the fingers on the card. Best to do this one card at a time so as not to confuse which card came from which slot.
The large plastic connectors will "slide apart" as well as unplug (male and female). This allows you to pull one pair of wires and reassemble the connector without the questionable wire. Again, be careful not to mix up the wires. Don't let the smoke out!
If you don't have a layout of your coach showing which card does what and what slot is wired for which function, check with CC for a copy from there files. They should have that on file and it seems all coaches are different. These documents will also identify which wire number goes where and what function it performs. Very important information to have. Those wire numbers have saved me a lot of time troubleshooting problems.
Enjoy your trip. Life on the road in a Prevost is the best!
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Thanks for the note Mike. Country Coach actually called me today. I guess they are back from the rally, and are trying at least to give me some guidance on what's going on.
They had me get into the mother board box (first bay), and check a relay there. It turns out I have the wrong power coming down to the main relay which switches a lot of the electronics, so many things are going on when they should be off, and off when they should be on.
He then had me open the lower door on drivers side (where the washer fluid is), and he believes the mother board in there might be wired wrong. Unfortunately, it's a bear to get to, and it appears that perhaps someone directly soldered some of the connections here, instead of being attached to connectors.
But, they believe this inverted signal is also at the root of my jake break. They indicated the jake break switching only happens when the ignition is on, and since mine is working inverted, I have no jake. it would be sure nice to get this going correctly!
But, it sounds like we may be onto something.
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Does your pyro guage have pollished stainless bezzle with visor with a engraved chrome faceplate? Hmmmmmmmmmmmm?