I was wondering if the data those of you who log fuel pressure get is a little noisy. For example I am using analog 2 for my fuel pressure and I will see values vary 6-8psi under full boost. This happens on the order of a few tenths of a second and my AFR stays fairly consistent. Is this just a case of the sampling?
For what it's worth the setup is a built B18C1 with a TR3030R turbo. I'm running ID 1000s, a fuel lab mini regulator, and a walbro 400lph (but I was also seeing this with my stealth340 pump and stock fpr). My base fuel pressure is around 40psi cold but drops to about 35psi when warm. I will use today as an example: fuel pressure went from 66psi to down 60psi up to 68psi in between 2-3 tenths of a second. This was top of 3rd gear at 20psi. As reference my AFR went from 11.8 down to 11.7 then up 11.9 at the same time.
TIA
Fuel pressure data log data question
Re: Fuel pressure data log data question
I would be more interested in seeing voltage at the fuel pump than actual pressure. Something definitely doesn't sound right. hook up a volt meter to the fuel pump leads and watch that during a pull. You may need larger gauge wiring to the fuel pump.. run a relay if you do that.
you might have a ripped diaphragm in your regulator, or leaky reference line? I doubt you're running out of pump.. you shouldn't be on that turbo at that pressure.
you might have a ripped diaphragm in your regulator, or leaky reference line? I doubt you're running out of pump.. you shouldn't be on that turbo at that pressure.
00' ITR turbo
b18c, manley 9:1, manley rods, supertech block guard welded in, stock head, AFI manifold, T67
b18c, manley 9:1, manley rods, supertech block guard welded in, stock head, AFI manifold, T67
Re: Fuel pressure data log data question
I haven't checked voltage at the pump on a pull yet but I do have a 30 amp relay and 10gauge wire for the pump (should have mentioned that). I double checked it and even rewired part of it to make sure that wasn't the problem. The fact that the AFR isn't really changing is what is making me wonder if it is something with the sensor.
I'm using a 0-100psi transducer I got from Innovate Motorsports. I think I have the voltage to psi conversion correct (it matches the FPR gauge at idle) but I cannot seem to find any information on the conversion formula. My next idea was to check the voltage at the pump when I get on it. I will have to have a passenger for that though. If the voltage is fine I am going to try one of the AEM transducers instead. I have already replaced the fuel filter and the pump is brand new. The fact that this was happening with the stock FPR and Stealth 340 pump makes me think a ripped diaphragm is not the issue,.
Thanks for your response.
I'm using a 0-100psi transducer I got from Innovate Motorsports. I think I have the voltage to psi conversion correct (it matches the FPR gauge at idle) but I cannot seem to find any information on the conversion formula. My next idea was to check the voltage at the pump when I get on it. I will have to have a passenger for that though. If the voltage is fine I am going to try one of the AEM transducers instead. I have already replaced the fuel filter and the pump is brand new. The fact that this was happening with the stock FPR and Stealth 340 pump makes me think a ripped diaphragm is not the issue,.
Thanks for your response.
Re: Fuel pressure data log data question
yeah you're right I re-read your post last night, definitely not a regulator issue.
It might be the transducer. I'm not sure how much noise you're getting and what the actual sampling rate is. If it's just a little blip for a tenth of a second, I'd say sampling error. I've always noticed my fuel pressure gauge holds solid if boost is at a stable pressure, but I'm sure the needle moves a bit.. but not 8 psi like what you're seeing.
Lot of variables.. not fun to troubleshoot.
It might be the transducer. I'm not sure how much noise you're getting and what the actual sampling rate is. If it's just a little blip for a tenth of a second, I'd say sampling error. I've always noticed my fuel pressure gauge holds solid if boost is at a stable pressure, but I'm sure the needle moves a bit.. but not 8 psi like what you're seeing.
Lot of variables.. not fun to troubleshoot.
00' ITR turbo
b18c, manley 9:1, manley rods, supertech block guard welded in, stock head, AFI manifold, T67
b18c, manley 9:1, manley rods, supertech block guard welded in, stock head, AFI manifold, T67
Re: Fuel pressure data log data question
I have been pulling my hair out for a week now. I appreciate your help. I didn't get to take it out for a pull today but I will try to do it tomorrow to see what pump voltage does. On Thu I will be putting the car back on the dyno to see if it is still doing it in fourth gear, that is where the lean issues were really showing up before. I want to video the mechanical fuel pressure gauge on the reg to see if it is showing the same fluctuations. My guess is they will not show up. If that is the case I will try a new transducer.Jan Niemi wrote:yeah you're right I re-read your post last night, definitely not a regulator issue.
It might be the transducer. I'm not sure how much noise you're getting and what the actual sampling rate is. If it's just a little blip for a tenth of a second, I'd say sampling error. I've always noticed my fuel pressure gauge holds solid if boost is at a stable pressure, but I'm sure the needle moves a bit.. but not 8 psi like what you're seeing.
Lot of variables.. not fun to troubleshoot.
Re: Fuel pressure data log data question
The transducer might also need a snubber because the pulses in the fuel rail might be causing havoc on the load cell inside the transducer.
I also found in my past life as a test engineer that transducers are sensitive to proper grounding, ground loops, general electrical noise, large error bands, drifting, non-linearity and other problems. It's tough to find instruments suitable to permanently sit on a car engine and work like they should not to mention being connected to a data collection device that can accurately convert the signal.
I also found in my past life as a test engineer that transducers are sensitive to proper grounding, ground loops, general electrical noise, large error bands, drifting, non-linearity and other problems. It's tough to find instruments suitable to permanently sit on a car engine and work like they should not to mention being connected to a data collection device that can accurately convert the signal.
00' ITR turbo
b18c, manley 9:1, manley rods, supertech block guard welded in, stock head, AFI manifold, T67
b18c, manley 9:1, manley rods, supertech block guard welded in, stock head, AFI manifold, T67
Re: Fuel pressure data log data question
Jan Niemi wrote:The transducer might also need a snubber because the pulses in the fuel rail might be causing havoc on the load cell inside the transducer.
I also found in my past life as a test engineer that transducers are sensitive to proper grounding, ground loops, general electrical noise, large error bands, drifting, non-linearity and other problems. It's tough to find instruments suitable to permanently sit on a car engine and work like they should not to mention being connected to a data collection device that can accurately convert the signal.
I can say I think the ground is good. It is grounded to the thermo housing and that is nice and clean. I even used a dab of dielectric grease just to make sure. The pulse idea is interesting to me because the stock Honda rail has something on it to deal with the pulses, correct? The sensor is isolated from most of the engine vibration, I have it in the line just after the fuel filter, mounted on the firewall. I used a 6an nitrous solenoid 1/8npt port.