I just wanted to post this because this forum helped me a lot in diagnosing the issues I was having with my engine,
2003 F115 with ~950 hours started randomly sputtering, surging, and stalling above 4000RPM, running under 4000 it seemed to run fine, all signs pointed to a classic clogged VST issue, so I removed the VST tank to check the filter, filter was fairly clean, so I went ahead and replaced the pump while I had it apart as well. Threw it all back together and had the same issue...
OK... went and got a fuel pressure tester, took her out on the water and fuel pressure was steady the entire time it was bucking and jerking, hmm fuel ruled out, changed spark plugs, checked all wires and connections to coils and plugs, all look good. Same issue.
Hooked up YDS to the motor, all looked OK, brought my laptop out on the water, once I got it up to higher RPM I could see YDS battery voltage drop to ~3-4volts, TPS drop to ~.5 volts, and throttle opening move into the negative range.
OK all very weird... Removed and checked all connections to ECU, no issues there.
During my testing I also noticed that the motor sometimes would not shut off when I switched the key to off position, I would have to kill it with the battery switch itself. Weird. (I later noticed that many people with a failing ECU had this issue)
While I was messing around with the connections I had YDS hooked up at the same time, I noticed that when I bumped the ECU the voltage would move from ~12.5v down to ~3-4 and TPS voltage would also get all out of wack
I was able to replicate the issue by just tapping on the ECU with a screwdriver. I unbolted the ECU from the motor and was able to get it to work properly if I held steady pressure on the center of the ECU body...
All signs pointed to bad ECU, luckily I was able to track one down locally, swapped it out, and all is right in the world.
I know it is a rare part to have go bad on you, but I just want to let you guys know that it does happen and YDS was crucial in determining the issue!
So if you are having a strange issue that you believe is ECU related, dont be afraid to tap on that thing and see if you can replicate the issue!
Thanks for all the help and I hope this helps some poor sap like me in the future in figuring out their issues with their F115
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Screen caps from YDS
Note the wacky battery voltage, TPS voltage, and throttle opening angle.
I confirmed voltage was good going into the ECU itself, and confirmed TPS voltage was correct using my multimeter
Tapping the ECU with my screwdriver instantly changed the voltages back to normal and fixed the throttle opening angle, very easy to see the change on YDS
2003 F115 with ~950 hours started randomly sputtering, surging, and stalling above 4000RPM, running under 4000 it seemed to run fine, all signs pointed to a classic clogged VST issue, so I removed the VST tank to check the filter, filter was fairly clean, so I went ahead and replaced the pump while I had it apart as well. Threw it all back together and had the same issue...
OK... went and got a fuel pressure tester, took her out on the water and fuel pressure was steady the entire time it was bucking and jerking, hmm fuel ruled out, changed spark plugs, checked all wires and connections to coils and plugs, all look good. Same issue.
Hooked up YDS to the motor, all looked OK, brought my laptop out on the water, once I got it up to higher RPM I could see YDS battery voltage drop to ~3-4volts, TPS drop to ~.5 volts, and throttle opening move into the negative range.
OK all very weird... Removed and checked all connections to ECU, no issues there.
During my testing I also noticed that the motor sometimes would not shut off when I switched the key to off position, I would have to kill it with the battery switch itself. Weird. (I later noticed that many people with a failing ECU had this issue)
While I was messing around with the connections I had YDS hooked up at the same time, I noticed that when I bumped the ECU the voltage would move from ~12.5v down to ~3-4 and TPS voltage would also get all out of wack
I was able to replicate the issue by just tapping on the ECU with a screwdriver. I unbolted the ECU from the motor and was able to get it to work properly if I held steady pressure on the center of the ECU body...
All signs pointed to bad ECU, luckily I was able to track one down locally, swapped it out, and all is right in the world.
I know it is a rare part to have go bad on you, but I just want to let you guys know that it does happen and YDS was crucial in determining the issue!
So if you are having a strange issue that you believe is ECU related, dont be afraid to tap on that thing and see if you can replicate the issue!
Thanks for all the help and I hope this helps some poor sap like me in the future in figuring out their issues with their F115
----
Screen caps from YDS
Note the wacky battery voltage, TPS voltage, and throttle opening angle.
I confirmed voltage was good going into the ECU itself, and confirmed TPS voltage was correct using my multimeter
Tapping the ECU with my screwdriver instantly changed the voltages back to normal and fixed the throttle opening angle, very easy to see the change on YDS