Diagnostic help please

[acecase09]

Well I am reaching out to anyone who reads this for ideas. I am not in anyway bashing CSC or their support, they have been great, and they are doing everything they can.

First a few facts. I am by no means an inexperienced mechanic. I have 30 years of experience. I am also an IBEW wireman/ welder by trade. I have a 2019 RX3 with 786 miles. Shortly before the 500 miles was up, the speedo quit displaying speed and the abs quit. It was found while checking battery connections that a frame screw had been put through the + cable and was causing an intermittent ground. There is a pic of that attached. CSC sent me a new ABS unit, which controls both the abs and the speedo display.

Right after that, about 550 miles in, the bike would not idle down and continued to climb in rpm on its own until it hit rev limiter or it was shut off. Fun ride home let me tell ya, it had no power, bogged, popped and surged.

You can see that in this link:



Note on above, I did not blip the throttle, it did that itself.

I checked all connections and cleaned the O2 sensor and the O2 sensor did the trick. Joey from CSC sent me a new O2 sensor. Another fact is that I bought a brand new motorcycle to ride while I was doing/having some extensive work done on my truck. Its my primary ride to and from work, therefore, I kinda have to ride it.

A day or two after I cleaned the sensor, waiting on the new one from CSC, it dii it again. In the shop, I noticed that the crankcase vent tube was full of liquid, which turned out to be gas. Checking the oil revealed the crankcase to have a substantial amount of fuel in it. On the phone with Joey at CSC, he figured the Injector was leaking. He sent me an injector and loaned me a scan tool as well as including a new oil filter and oil.

Now I have been riding and racing for 25 years. I carried an AMA supersport license for years. I have ridden just about anything that can be ridden. My impression of the RX3 was it doesn’t feel smooth, its buggy to start, and there should be more power. I also thought the fuel economy was a joke. 60-70 mpg, not even close. I chalked it up to the fact is was Chinese and it is not a BMW, Ducati or even a Honda. After replacing the Injector, O2 sensor and oil, I took it out. It was like a new machine. I spent 7 hours ridding offroad and it was running like a $15K motorcycle. For the first time since I bought it, I was truly happy with my purchase.

Then yesterday on the way home from work, this video was taken.



It was idling high and had no power. It never over revved like it did before, but was struggling to do 35 mph. I left the highway and got on some dirt, so I would not get run over and had to stop for 5-10 min for a train. When I restarted it, idle was normal, however it was still not running smooth. At constant throttle, it was surging and falling slightly. Listen to the video above, trying to throttle up, it shuts off, hard. After the train, here is what it was doing:





This morning on the way into work, it was not running perfect, and power was a little low, but it got me to work with no issues. I am expecting to ride home in some heavy rain, so that might be more of an adventure than I want. I am in Jackson SC, 29831 if you want to pull up our weather and see what is in the forecast.

In the area where I am we have a couple of bike shops. All of them have a 3-5 month lead time on repairs. Well the four good ones do. The others are ok for tires and such, but nothing that involves brain function. Because of that I am stuck working on this myself.

Writing this, I have not heard back from CSC yet, that are not open and were closed Monday. I intend to take the scan tool with me and next time it act up, check the live data. I am interested in the throttle position sensor value, but am open to anything. No codes have been found, stored, pending or historic. Throttle position sensor value was normal when I tested it. Charging system and battery have been extensively monitored and tested, both are in excellent health. O2 sensor and Injector were replaced. Every connector in the wiring harness was checked for tension and engagement. I need Ideas. What do you think I should check? My only two thoughts is a going bad throttle sensor or the intermittent ground damaged the ecm unit.

Again, CSC has done and is doing everything they can to help me. They haven’t offered to replace the thing yet, but other than being a little slow on the email replies, they are being top notch.

[Working_ZS]

A couple things that i would check right off the bat:

1. Check for a vacuum leak; this would allow un-metered air into the engine and the ECU is picking this up via the O2 sensor, feeding in more fuel and causing the RPMs to rise. To do this, use starting fluid/ether to spray around the intake area and see if the engine RPMs changes when you do so. Also, use the scantool to look at the short and long term fuel trims. If they are more than 10% positive, there is definitely a leak somewhere.

2. Pull the inspection port covers for the timing chain and see if it is off a tooth or two. Also check the timing chain for excessive slack.

3. Check the ignition coil and wire for high voltage leakage. Use a screw driver wrapped with a wire clamped to a ground to do this. A test light will also work.

4. Inspect the idle air stepper motor/throttle valve and its passage. If they are dirty, clean them.

5. Disconnect your throttle cable and make sure it is not binding.

6. Use the scantool to check the output of the throttle position sensor at idle. If it changes without any throttle input, it's bad.

[Working_ZS]

One more thing - have you done the 500 mile valve clearance check and adjustment? If not, do so. If you have, you may want to check it again, just to make sure that a lock nut has not loosened and allowed an adjuster screw to move.

[acecase09]

Originally Posted by Working_ZS

A couple things that i would check right off the bat:

1. Check for a vacuum leak; this would allow un-metered air into the engine and the ECU is picking this up via the O2 sensor, feeding in more fuel and causing the RPMs to rise. To do this, use starting fluid/ether to spray around the intake area and see if the engine RPMs changes when you do so. Also, use the scantool to look at the short and long term fuel trims. If they are more than 10% positive, there is definitely a leak somewhere.

2. Pull the inspection port covers for the timing chain and see if it is off a tooth or two. Also check the timing chain for excessive slack.

3. Check the ignition coil and wire for high voltage leakage. Use a screw driver wrapped with a wire clamped to a ground to do this. A test light will also work.

4. Inspect the idle air stepper motor/throttle valve and its passage. If they are dirty, clean them.

5. Disconnect your throttle cable and make sure it is not binding.

6. Use the scantool to check the output of the throttle position sensor at idle. If it changes without any throttle input, it's bad.

Thanks for the info. I have always used a unlit propane torch to check for vacuum leaks. My bike did not respond to any area so I think it's tight. As for the valves, they are right in spec. I will check them again, but I doubt they have moved. As for the throttle cable, I took it loose from the cam and it was still acting screwy. As for the throttle sensor, scan tool shows a .001 variation from rest. When you twist and hold, it's rock steady. I intend to plug it in to scanner next time it acts up, but in rain, not really an option. As for the map or whatever zong calls it, I haven't checked anything other than the connection. Checked just now when I walked by parking lot and no liquid in vent tube drain, and oil level constant. So improvement there. Thank you again for the ideas, I will look at it again tonight.

[Working_ZS]

Based on what you've said, I would definitely be looking at the idle air stepper motor and its passages. You've eliminated a vacuum leak, via the propane, and ruled out the throttle cable by disconnecting it. Yet you are still down on power, so that leaves valves, air fuel mixture, via the throttle body, and timing/ignition. In one of your videos, I did notice a regular misfire, so I would definitely check out the ignition coil and its wire for high voltage leaks. Also, it seems obvious, but check the compression of the engine. Who knows, it could just be a loose spark plug or bad terminal on the high tension lead. I recall a few RX3 owners who have had problems with the coil wire terminal not connecting firmly to the spark plug.

As for the throttle body, which includes the idle air stepper motor, you might just ask CSC to send you a new one altogether, rather than mess with the one that you have. With only 768 miles on it, it is probably not that dirty, which leaves a possible bad throttle body or bad stepper motor. Just because it's new, doesn't mean that it is good. It's probably easier to just change out the whole assembly, if you can get one from CSC, which most likely will not be a problem. If you had an oscilloscope, you could tap into the ECU to stepper motor wire and see if the ECU is actually commanding the valve to open, raising the idle like it does, as well as seeing if it is active at higher throttle positions, when it should not be, which would let too much air into the engine. Definitely check those fuel trims, via the scantool, so that you can find out if the engine is running lean or rich. That will tell us a lot.

[acecase09]

I talked to CSC and they are sending a new throttle body. Given that I just changed the injector, that will pretty much replace every sensor. If the problem still exists, we will replace the ECU. The ECU could have been damaged by the intermittent short in the + cable. I have the scan tool in the luggage and when it acts up again, I will screen shot all the live data fields. Right now, everything is showing normal.

As for the spark plugs and wire, they are good as is the compression and leak down.

Thank you again for the info, I will keep this updated as it happens. Thanks again to CSC for the support and help.

[acecase09]

Update:

I received the throttle body and installed it. Seems to be fine , but haven't ridden it. We are flooded here. Roads are either closed or gone. I am hoping to get out this weekend.