Troubleshooting throttle circuit. Lets compare notes
08-23-2005 | 07:53 PM
#1
Troubleshooting throttle circuit. Lets compare notes
I am try to troubleshoot an intermittent "RC-OFF" conditions, that I think is being caused by my un-conventional throttle circuit on the Jet powered streetluge. Occasionally, when I let the throttle off quickly while traveling at speeds over 70 mph the P200 flames out. I was able to keep the ECU alive long enough to get back to the pit area a few times and each time the reason was RC-OFF. I have moved wires and banged things around trying to simulate road vibration with it running to see if maybe I had some loose wires or connections, but could not cause the condition. I am beginning to suspect the mechanical to electrical interface that controls the Pulses in to the ECU. Perhaps I do not have enough throttle range (min to max), causing it to be extra sensitive, although it seems like I have plenty.
Short description of circuit- Throttle cable pulls on a spring loaded Throttle Pot (potentiometer 0-500 ohms). Trim switch, switches in a 100 ohm resistor in series to the throttle pot. This feeds a PIC's chip programmed to make very stable pulses (simulates RC Receiver) that feeds the ECU (Jet Cat Version 5.0 )
Here are the numbers I get when doing the Learn RC procedure
Throttle @ minimum =683 to 688 (varies slightly due to mechanical slop returning throttle to minimum)
Trim @ Maximum = 794
Throttle @ Maximum= 1232
My assumption is that when I released the throttle, that the count would have to go below 794 to get an RC-Off condition
Throttle action seems to produce a steady up or down count as I move it throughout the range.
What numbers do you get? is there a norm? I dont think it matters what engine it is, just the ECU and Receiver combo
Thanks in advance for your help.
Bob
If you've missed it, I posted a link to the video of the drag race run from this weekend in the other thread and one of J34 powered jet cars
[link=http://www.jetluge.net/video.html/jetlugedragrace.wmv]Jet Luge Drag Race.[/link]
Short description of circuit- Throttle cable pulls on a spring loaded Throttle Pot (potentiometer 0-500 ohms). Trim switch, switches in a 100 ohm resistor in series to the throttle pot. This feeds a PIC's chip programmed to make very stable pulses (simulates RC Receiver) that feeds the ECU (Jet Cat Version 5.0 )
Here are the numbers I get when doing the Learn RC procedure
Throttle @ minimum =683 to 688 (varies slightly due to mechanical slop returning throttle to minimum)
Trim @ Maximum = 794
Throttle @ Maximum= 1232
My assumption is that when I released the throttle, that the count would have to go below 794 to get an RC-Off condition
Throttle action seems to produce a steady up or down count as I move it throughout the range.
What numbers do you get? is there a norm? I dont think it matters what engine it is, just the ECU and Receiver combo
Thanks in advance for your help.
Bob
If you've missed it, I posted a link to the video of the drag race run from this weekend in the other thread and one of J34 powered jet cars
[link=http://www.jetluge.net/video.html/jetlugedragrace.wmv]Jet Luge Drag Race.[/link]
08-23-2005 | 08:22 PM
#2
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From: Putnam Valley,
NY
RE: Troubleshooting throttle circuit. Lets compare notes
Bob, it seems that you are looking in the correct area, RC off is RC off, some how the ECU is seeing that command. If its only happening at speed maybe your pots cant take the vibration from the luge at speed. Does this problem happen when standing still? Nice to meet you at Liberty Bell, that Luge is cool.
Don
Don
08-23-2005 | 08:43 PM
#3
My Feedback: (85)
RE: Troubleshooting throttle circuit. Lets compare notes
Don has made some very valid points...Always check for a mechanical problem before getting into the electronics.
If it does turn out to be in your electronics interface that you made (voltage drops so low that the ECU sees it as an off state) you might want to contact Matt (aka Mr Matt). He knows the ins and outs of the JetCat engines and is an electronics genious. He represents JetCat in the turbine forum.
Kevin
If it does turn out to be in your electronics interface that you made (voltage drops so low that the ECU sees it as an off state) you might want to contact Matt (aka Mr Matt). He knows the ins and outs of the JetCat engines and is an electronics genious. He represents JetCat in the turbine forum.Kevin
08-23-2005 | 08:43 PM
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From: Ft Wayne, IN
RE: Troubleshooting throttle circuit. Lets compare notes
When I had such a problem with my RAM-100, I programmed the ECU with the trim at the middle, then after startup, I will bump the trim to max. Whenever you chop your throttle to min, your trim is at Max and above the low throttle shutoff hence preventing the turbine from sensing low throttle pulse which in turn will not allow it to shutdown.
08-23-2005 | 09:13 PM
#5
RE: Troubleshooting throttle circuit. Lets compare notes
Only happens when I "Chop" ( I like that term) the throttle to minimum when trying to slow from high speed motion. I can not replicate the prob no mater how hard I slap the luge and throttle around sitting still with the turbine running. All of your ideas are valid, but I need to see if the ECU count for each position of trim/ throttle is even in the ballpark since i have nothing to compare to. My question was sort of a survey of notes to see what several other pilots get on their varied setups for the learn RC Parameters. I would like to make mine somewhere in the average of the info I get and then try it again. I have thought of "padding the trim" if need be but would rather not. I will be in touch with Mr Matt also, he has been great help with everything.
Although not a genious, I am also a, so called "WIZ" in the electronics design and real life production of both RF and digital circuits and systems for the Naval Research Lab in DC. I am not saying that as a bragging statement, believe me, I am just letting people know incase you also need help in troubleshooting. I am green and wet behind the ears when it comes to the R/C world's specific components, but have extensive experience in solving RFI / EMI problems on the ground and in space, for example. I would like to give as much as I have taken from this forum.
thanks
bob
Although not a genious, I am also a, so called "WIZ" in the electronics design and real life production of both RF and digital circuits and systems for the Naval Research Lab in DC. I am not saying that as a bragging statement, believe me, I am just letting people know incase you also need help in troubleshooting. I am green and wet behind the ears when it comes to the R/C world's specific components, but have extensive experience in solving RFI / EMI problems on the ground and in space, for example. I would like to give as much as I have taken from this forum.
thanks
bob
08-23-2005 | 09:26 PM
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From: winter springs,
FL
RE: Troubleshooting throttle circuit. Lets compare notes
Next time it does this, use the gsu to play back the last 8 seconds of the run. From that data you can possibly see where the "stick" command was. I assume that stick down and trim down would show a 0 or similar and stick full up shows a 100. I know when I fly my KC the stick position is always reading 100.....
From this data you can see if the ecu is getting erroneous data, or true user input.
Or I could be an Idiot.......
Later
From this data you can see if the ecu is getting erroneous data, or true user input.
Or I could be an Idiot.......
Later
08-23-2005 | 10:04 PM
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From: Milton,
ON, CANADA
RE: Troubleshooting throttle circuit. Lets compare notes
Hi Bob
It sounds to me like your throttle pot is over travelling when you release the throttle. Follow Ghostrider's suggestion about adjusting the trim point.
Ed
ORIGINAL: lugebob
I am try to troubleshoot an intermittent "RC-OFF" conditions, that I think is being caused by my un-conventional throttle circuit on the Jet powered streetluge. Occasionally, when I let the throttle off quickly while traveling at speeds over 70 mph the P200 flames out. I was able to keep the ECU alive long enough to get back to the pit area a few times and each time the reason was RC-OFF. I have moved wires and banged things around trying to simulate road vibration with it running to see if maybe I had some loose wires or connections, but could not cause the condition. I am beginning to suspect the mechanical to electrical interface that controls the Pulses in to the ECU. Perhaps I do not have enough throttle range (min to max), causing it to be extra sensitive, although it seems like I have plenty.
Short description of circuit- Throttle cable pulls on a spring loaded Throttle Pot (potentiometer 0-500 ohms). Trim switch, switches in a 100 ohm resistor in series to the throttle pot. This feeds a PIC's chip programmed to make very stable pulses (simulates RC Receiver) that feeds the ECU (Jet Cat Version 5.0 )
Here are the numbers I get when doing the Learn RC procedure
Throttle @ minimum =683 to 688 (varies slightly due to mechanical slop returning throttle to minimum)
Trim @ Maximum = 794
Throttle @ Maximum= 1232
My assumption is that when I released the throttle, that the count would have to go below 794 to get an RC-Off condition
Throttle action seems to produce a steady up or down count as I move it throughout the range.
What numbers do you get? is there a norm? I dont think it matters what engine it is, just the ECU and Receiver combo
Thanks in advance for your help.
Bob
If you've missed it, I posted a link to the video of the drag race run from this weekend in the other thread and one of J34 powered jet cars
[link=http://www.jetluge.net/video.html/jetlugedragrace.wmv]Jet Luge Drag Race.[/link]
I am try to troubleshoot an intermittent "RC-OFF" conditions, that I think is being caused by my un-conventional throttle circuit on the Jet powered streetluge. Occasionally, when I let the throttle off quickly while traveling at speeds over 70 mph the P200 flames out. I was able to keep the ECU alive long enough to get back to the pit area a few times and each time the reason was RC-OFF. I have moved wires and banged things around trying to simulate road vibration with it running to see if maybe I had some loose wires or connections, but could not cause the condition. I am beginning to suspect the mechanical to electrical interface that controls the Pulses in to the ECU. Perhaps I do not have enough throttle range (min to max), causing it to be extra sensitive, although it seems like I have plenty.
Short description of circuit- Throttle cable pulls on a spring loaded Throttle Pot (potentiometer 0-500 ohms). Trim switch, switches in a 100 ohm resistor in series to the throttle pot. This feeds a PIC's chip programmed to make very stable pulses (simulates RC Receiver) that feeds the ECU (Jet Cat Version 5.0 )
Here are the numbers I get when doing the Learn RC procedure
Throttle @ minimum =683 to 688 (varies slightly due to mechanical slop returning throttle to minimum)
Trim @ Maximum = 794
Throttle @ Maximum= 1232
My assumption is that when I released the throttle, that the count would have to go below 794 to get an RC-Off condition
Throttle action seems to produce a steady up or down count as I move it throughout the range.
What numbers do you get? is there a norm? I dont think it matters what engine it is, just the ECU and Receiver combo
Thanks in advance for your help.
Bob
If you've missed it, I posted a link to the video of the drag race run from this weekend in the other thread and one of J34 powered jet cars
[link=http://www.jetluge.net/video.html/jetlugedragrace.wmv]Jet Luge Drag Race.[/link]
08-24-2005 | 12:37 AM
#8
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RE: Troubleshooting throttle circuit. Lets compare notes
Hi Bob,
I would look at you trim switch, to make sure it is not having some vibration problem. Also, I am not so sure how hard it is to do, but you can modify the trim circuit to get more of a difference between the low trim shutoff and low throttle (high trim position). You really can't mess it up, cause if you enter a trim value in that is out of range, the ECU will not learn it. Once the high trim is learned, the ECU linearizes the remaining range you have from high trim to full throttle. You loose a bit of throttle resolution but that is completely irrelevant in what we are doing.
But remember if that throttle trim switch is glitching, no matter how large a difference there is between the low throttle trim shutoff and high trim, you are still going to get a shutdown.
Did you program the PIC? If so you might want to add some low pass filtering to the pot input.
Good luck,
I would look at you trim switch, to make sure it is not having some vibration problem. Also, I am not so sure how hard it is to do, but you can modify the trim circuit to get more of a difference between the low trim shutoff and low throttle (high trim position). You really can't mess it up, cause if you enter a trim value in that is out of range, the ECU will not learn it. Once the high trim is learned, the ECU linearizes the remaining range you have from high trim to full throttle. You loose a bit of throttle resolution but that is completely irrelevant in what we are doing.
But remember if that throttle trim switch is glitching, no matter how large a difference there is between the low throttle trim shutoff and high trim, you are still going to get a shutdown.
Did you program the PIC? If so you might want to add some low pass filtering to the pot input.
Good luck,
08-24-2005 | 07:23 AM
#9
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From: South Plainfield, NJ
RE: Troubleshooting throttle circuit. Lets compare notes
Bob,
You may also want to use a variable speed vibrator to test your components. I've had receiver problems that would only show up when hit with certain freqs.
Can you put a lighter spring on the pot?
Mark
You may also want to use a variable speed vibrator to test your components. I've had receiver problems that would only show up when hit with certain freqs.
Can you put a lighter spring on the pot?
Mark
08-24-2005 | 09:10 AM
#10
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RE: Troubleshooting throttle circuit. Lets compare notes
Yes of course the pot could also have some vibration problem, if you want to eleiminate the pot go to an optical encoder for the throttle. Of course I do not really know how much throttle control you really need, maybe a 3 position switch or something.
08-24-2005 | 11:15 AM
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From: Ft Wayne, IN
RE: Troubleshooting throttle circuit. Lets compare notes
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