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I am experiencing a rough idle and bad fuel mileage and am hoping you fella’s can point me in the right direction after deciphering this live data file. I started from a dead stop and shortly after the 1-2 shift I had the pedal to the floor. I’m sure ya’ll will want more info so thank you for the help and fire away.
What mods have been done to this truck? Did you edit the file before posting it? Was this just a brief WOT run or something? Have you checked fuel pressure yet or looked for air in fuel?
What mods have been done to this truck? Did you edit the file before posting it? Was this just a brief WOT run or something? Have you checked fuel pressure yet or looked for air in fuel?
truck is stock
did not edit but it seems like I didn’t capture the entire run. I started from a dead stop and after the 1-2 shift I had it at WOT.
Fuel pressure drops to 55lbs during hard acceleration.
Have not checked for air in fuel.
Yeah I noticed 2 gaps of almost exactly 5 seconds of gap in the data. Pretty sure I've never seen that, at least not one that wasn't on purpose. @BWST how about you, ever seen gaps like that in the data stream? What I thought was strange is the first one is exactly 5 seconds to the millisecond, and the second is very close to exact also. I bet it's Skynet, the machines are almost ready to takeover.
I noticed your MAP PID did not report any data, but it was also logging in Hz instead of PSI. I would start by checking to make sure the MAP sensor is working. On a cold engine, with the engine off and ignition on, EBP, MAP and BARO should be within .5 PSI of each other. The odd ball is suspected bad and should be replaced or troubleshot.
Charted data is pasted below and chart is attached.
Recommend another log capturing about 1 minute of a warmed up idle. The short section of idle posted above looks smooth, but the fuel pulsewidth is unusually high at 3.44ms. Normal for a warmed-up engine with stock split shot injectors is about 2.75ms. IPR% and ICP are in the normal range for idle, so I'm questioning the data here.
Was your idle rough while you were taking this data?
The gaps in the data are strange as well. Like udsuth78 said, about 5 second gaps in two places, yet the data right at those jumps is normal. Look at VSS - it is increasing normally. If there was a 5 second gap in the data there, VSS would have jumped 15-20MPH on his WOT run.
Zooming out and looking again, there is missing data between several rows around this area. VSS increases normally in the green highlighted cells, then skips about 1MPH with each row of data (orange highlight).
So I don't trust this data file. This can sometimes be caused by a poor connection between the OBDII dongle and the OBDII port - we saw something like this with @ArmyLifer 's rig once. It was a bit different though - regular dropouts in the data.
What brand/model hardwired USB OBDII dongle are you using? You mentioned in your other thread you were using an ATOTO head unit hardwired to the OBDII via USB.
I noticed your MAP PID did not report any data, but it was also logging in Hz instead of PSI. I would start by checking to make sure the MAP sensor is working. On a cold engine, with the engine off and ignition on, EBP, MAP and BARO should be within .5 PSI of each other. The odd ball is suspected bad and should be replaced or troubleshot.
Charted data is pasted below and chart is attached.
MAP sensor is brand new Motorcraft from an online retailer. I guess I missed that the MAP needed to be set to psi so I will change that when I get home. I do know that it wasn’t reading so I unplugged a plugged in again. No change. Could there be something else causing it not to read?
Recommend another log capturing about 1 minute of a warmed up idle. The short section of idle posted above looks smooth, but the fuel pulsewidth is unusually high at 3.44ms. Normal for a warmed-up engine with stock split shot injectors is about 2.75ms. IPR% and ICP are in the normal range for idle, so I'm questioning the data here.
Was your idle rough while you were taking this data?
The gaps in the data are strange as well. Like udsuth78 said, about 5 second gaps in two places, yet the data right at those jumps is normal. Look at VSS - it is increasing normally. If there was a 5 second gap in the data there, VSS would have jumped 15-20MPH on his WOT run.
Zooming out and looking again, there is missing data between several rows around this area. VSS increases normally in the green highlighted cells, then skips about 1MPH with each row of data (orange highlight).
So I don't trust this data file. This can sometimes be caused by a poor connection between the OBDII dongle and the OBDII port - we saw something like this with @ArmyLifer 's rig once. It was a bit different though - regular dropouts in the data.
What brand/model hardwired USB OBDII dongle are you using? You mentioned in your other thread you were using an ATOTO head unit hardwired to the OBDII via USB.
yes, engine was warm for the idle time recorded. Wasn’t sure what kind of live data would be needed so I started with a dead stop rip. I can do a 1 minute data log this evening and post it as well. Dongle is a Chinese piece from Amazon. I can tell you the exact model and make later on.
It's possible that OBDII dongle is the problem then. Only a few are tested to work well with FORScan/FSL. Check Forscan.org or my FORScan Q&A thread for dongles that work.
As soon as you change the MAP units from Hz to PSI, that PID should begin to read valid data.
It's possible that OBDII dongle is the problem then. Only a few are tested to work well with FORScan/FSL. Check Forscan.org or my FORScan Q&A thread for dongles that work.
As soon as you change the MAP units from Hz to PSI, it should begin to read valid data.
I just ordered the BT dongle recommended by FORScan.org. Will be here Thursday. Thank you guys.
I am waiting for the BT dongle to get here but in the meantime I am gonna post a log of 1 min of idle with rough idle with the current set up. It may be bogus data but it also may show that the dongle is the difference. I’ll post the same idle data once I have the new adapter. Thank you again.
Definitely can see your rough idle there. Here is a comparison between your file and one from my truck. The vertical scales have been adjusted to better see the data:
Air in fuel is a good thing to rule out.
Does the idle smooth out if you unplug the ICP sensor?
If not, the next thing we recommend is to clean/reseal the IPR valve, or replace it with a Motorcraft part from a reputable seller. That part has a large effect on idle quality.
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