Hi, I’m in the process of tuning my R53 mini on an EMU Black. I’m using V3 software and I’ve found that if the car is allowed to idle for a long time it gradually goes lean. Sometimes as much as 20% lean. Right now it’s pretty cold out where I live, around -5C.
I believe this is due to the sensor getting heat soaked in the manifold and reporting a higher IAT than is real. I haven’t verified this, but plan to eventually with a thermocouple. For now I’ve applied a bandaid fix of allowing the EMU to apply as much as +25% STFT which allows the fuel to stay on target even if there is heat soak, but this isn’t a good long term solution. It doesn’t ever seem to happen when I’m driving, only if the car is allowed to sit idling for a long time (~15 mins). I’m using the stock TMAP sensor, and sensor calibrations borrowed from the V2 software base map.
Does anyone have ideas on how to fix this issue? Thanks!
Can u post a pictur where the sensor exactly is mounted.
Beside a complex model, there is no real SW solution for a heat soaked sensor. The real solution is to move the sensor further away from the manifold or any metal parts.
With SW u judt can di bad workarounds…it is actually an HW issue.
Had the same problem with my 1.8t engine, where the iat sensor is in the metal manifold. I moved it to a plastic part further away and issue was gone.
Yes, the sensor is stock location and is a TMAP so it’s giving both pressure and temperature. It’s bolted into the aluminum intake manifold. The issue is that there isn’t really a place to put it that isn’t metal. The whole intake after the supercharger is metal.
I don’t know how it’s corrected in the factory ECU.
I have made the table -5 to 70C in 5C increaments and i add almost 10% fuel at 60celsius with the 20-30c being the 0% island. Since there is no way to disable IAT ideal Gas Law correction, because its in the algorithm of fuel caclulations. You can see how much IAT is ifluencing your situation by unplugging your IAT sensor and seeing the change in AFR from the Failsafe IAT value versus plugging in your IAT sensor back again. Also make sure your Charge Temp MAP is all set to 0.
Sometimes if the car has bad injection atomization (bad injection angle, large injectors with big fuel dropplets, low speed intake ports) even without changing IATs if the Intake manifold gets very hot you might get Rich AFR when you get REAL high Intake temps. That wil be because fuel can sufficiently atomize and efficiently burn.
E.x. I got that in a sierra cosworth where they have installed for some reason x8 1050cc’s that inject all together at idle with a custom intake that has the inejctor spray onto the intake port.
As discussed in the thread, this is no solution.
It will improve ur situation, but at cost of accuracy in fueling in any other situation. IAT is a relevant value for airmass calculation. Without, VE won’t make sense anymore.
But if u want to do it, u can set iat sensor curve to a fixed value. But sooner or later u will run into other issues with that.
I disagree that it can’t be fixed, this is the OEM sensor location so that means BMW has some kind of solution for this issue on the stock ECU. Weather or not the EMU can mimics that is a different story, it may not be easily possible to fix it on this ECU. We’re not looking to break the ideal gas law, I’m just trying to add a slight correction during heat soak.
There was a suggestion in there to create a custom correction that references MAP IAT to injector duty. I set this up with a user function so that the correction is only engaged at idle. Which works for now.
It needs a bit more tweaking, the user function needs to be more than just “in idle”. Really what it needs is a way to detect the scenario that causes heat soak. It’s better than it was before though, and this is how I’m going to leave it until I think of a better idea.
I have the same problem. I think it can be fixed with a compensation map when the speed is closer to 0, using a delta value based on outside temperature and intake temperature, to fix fueling for heat soak, starting, and idle issues.
This is what I did, a correction table that adds injector PW when we are in idle and IAT is high. This works ok but as soon as you start moving the issue immediately comes back. Will need to consider other options to make it work better but its not half bad.
honestly i think it may be better to just allow the STFT to take care of it, because the problem with my method is that the correction is only applied when at idle. As soon as you start moving the correction is immediately removed which causes the mixture to go lean faster than the STFT can react.
If you leave it controlled by STFT the trim can slowly react as the heat soak gradually goes away.
I came across this issue 5 years ago on my R53. I made a custom correction table that activates based on vehicle speed with certain delays. I can post my settings if you’re interested?
The other (expensive) option is to fit the TPE plastic manifold which I imagine would solve the issue.
Yes! If you’re willing to share I would be very appreciative! I’m especially curious how you’re implementing the delays. This would be a much better solution than what I’m using now.
Yes i agree the TPE manifold would probably help but i”m not looking to drop 1200€ right now haha
This is interesting, i coped the charge air temp map from the V2 base map and its super aggressive, at idle charge temp is mostly CLT, almost 80% CLT and only about 20% IAT.
This causes there to be a “shelf” in my VE when it switches from primarily CLT based to primarily IAT based.
I’m wondering if the basemap table for charge temp is incorrect or maybe shouldn’t be used at all….
