M130 rich/lean at very low load

I have a UTV with a M130 I'm chasing a odd issue. At very light load. 4k rpm and 40kpa 10-15 mph. The closed loop keeps wanting to max out pulling fuel -20%. I keep removing more and more fuel with no change to trim. I'm to the point of lean that it surges and stumbles when accelerating from this area of the map. I tried to richen up the lambda aim in this area since I had it at 1.0 and no change. Really itching my head on this one.

Can you upload a log (or point us to where we could download it) showing the problem?

Are there any other compensations active?

What is the Fuel Mixture Aim at this operating condition?

I don't see any other corrections. I feel like it's falsely seeing rich since the more fuel I pulled the worse it's ran. Around 18:00 you can see it. It's a super slow cruise in a neighborhood. I can't think of how it could be false, I thought maybe 1.0 lambda was to lean and causing it to miss and see the fuel.

A mis-fire (non-combustion) will read lean, not rich.

Is there any chance your changes are actually not going into the ECU? How are you making the changes (typing a value, using "=" math, using page up/down keyboard keys)? Are you saving your changes before disconnecting the ECU? I will admit, I've done that plenty of times myself.

I will look at your data tomorrow morning.

First, are your injectors ID1300cc (as noted in the comments), or 1700cc as selected for Fuel Injector Primary Calibration? If they are 1300cc, I would certainly change that in M1 Tune->Initial Setup->Injectors

Your Inlet Manifold Pressure Sensor Diag is "Translation Minimum" . I would have expected it to use Inlet Manifold Pressure Estimate Main, but that doesn't seem to be happening (first it's calibrated for Normally Aspirated, and secondly it shows much lower pressure that what is in your log). I would check with JRR on the behavior in this condition.

Have you considered using the Engine Efficiency Throttle table for the trim? This is probably what will allow you to fix this condition.

You also have a "Invalid Limit Angle" on your Fuel Cyl 1 Prim Out Diag. So I suspect your Injection Timing is not setup correctly. (M1->Tuning->Fuel Timing worksheet). Since you are running Flex Fuel (looks like E72 in this log), you might need to make sure the Alternative Fuel Timing and Alternative Fuel Timing Blend are correct. I would try changing Fuel Timing Primary Limit to 180.

The injectors are now 1700. I also changed my map sensor to a 4 bar and on E now. I feel this issue is new with these changes I have the low calibration set to 50kpa at .40v, I am below that I believe. Maybe I should adjust the settings there. I believe I have fuel timing at 460 both e85 and 91 Oct. Thank you!

The MAP Sensor translation table will extrapolate data off either end of the calibration table, so it will continue to read below the 50kPa value. The warning is triggered so that the tuner is aware of the sensor going outside of it's tuned parameters.

BlackRex that's how I read it. I did see somebody mention doing the extrapolation themselves to stay out of the warning. I didn't know if any of that info was current. Thank you!

Extrapolation on a linear calibration is quite easy to do, if you tell me your high and low values I can give you the extrapolated data.

In the logging, when the data extrapolates past your calibration, it flatlines at 42.8kpa, which would indicate that the sensor is not capable of measuring below this value (the diagnostic low is not triggered, meaning you haven't reached the diag low voltage)

Looking at the calibration you are running some kind of 4 bar Bosch flange mount sensor? Something like an 0 281 002 576?

Most of these 4 bar sensors were designed of use on diesels or charge pipes, so do not read below 40-50kpa a.

In this case, your sensor will not be suitable for giving you the resolution required for accurate load sensing at light load/overrun conditions. Ideally you would want a sensor capable of reading down to 20kpa

Yes it’s the bolt on map sensor with air temp. I assumed it went lower than 50kpa and .4v but now looking at the spec sheet it flat lines at .4v. I ordered a separate pressure sensor that’ll do down to zero kpa. Thank you!

Thank you! The better map sensor fixed my issue. Low load is nice and smooth now and fuel map looks much better