slowbutsteady
New Member
The engine runs okay at idle (600 RPM). At high idle the vehicle sounds like it is missing and the engine shakes and rpm sways from 1200 to 1500. The vehicle is not drive-able. The throttle is very touchy and can jump rpms from 1800 to 2500 and race. It seems to be able to manage max rpms so there is some control. I've seen others have had this problems but rarely do people seem to post the solution. I will take the time to do this as this H1 is my daily driver and I am stuck until fixed.
The problem got worse over a period of a week. At first it occurred a bit after start up. Then the RPMs swung a bit (about every 4-6 seconds about 10%. Now the swing is so great that the vehicle takes off to 50 MPH and then drops to 30 then back up to 40 and all over the place. The same thing happens (erratic rpm) i I leave the vehicle in Park and select different idle speeds.
So far I have:
1) Cleaned the air filter.
2) Checked the fuel filter.
3) I connected a 1/4" clear hose to the return line on the IP and there were no bubbles. Good fuel flow and it was clear.
4) I have pulled grounds, cleaned and tightened.
5) I am about to check optical sensor on IP or put an oscilloscope on signal lines to look for problems.
6) I checked the system data from a logger (ScanXL Professional) and I don't see any bad sensors.
7) The engine is reporting no error codes.
8) I tried another FSD (relocated, D-type) and same issues.
I will check the fuel pressure tomorrow and return line pressure.
I'd like not to replace the IP unless necessary. I can try to swap the ECM. I'd like any input on what I could look at that could explain the problem.
I will share what I find here and any signal waveforms if you have suggestions. This is the most annoying problem yet.
The problem got worse over a period of a week. At first it occurred a bit after start up. Then the RPMs swung a bit (about every 4-6 seconds about 10%. Now the swing is so great that the vehicle takes off to 50 MPH and then drops to 30 then back up to 40 and all over the place. The same thing happens (erratic rpm) i I leave the vehicle in Park and select different idle speeds.
So far I have:
1) Cleaned the air filter.
2) Checked the fuel filter.
3) I connected a 1/4" clear hose to the return line on the IP and there were no bubbles. Good fuel flow and it was clear.
4) I have pulled grounds, cleaned and tightened.
5) I am about to check optical sensor on IP or put an oscilloscope on signal lines to look for problems.
6) I checked the system data from a logger (ScanXL Professional) and I don't see any bad sensors.
7) The engine is reporting no error codes.
8) I tried another FSD (relocated, D-type) and same issues.
I will check the fuel pressure tomorrow and return line pressure.
I'd like not to replace the IP unless necessary. I can try to swap the ECM. I'd like any input on what I could look at that could explain the problem.
I will share what I find here and any signal waveforms if you have suggestions. This is the most annoying problem yet.