2018 Mustang GT - Large EQ Cmd swings and opposite EQ Actual
2018 GT Auto, PMAS 120 CAI and LTH. Car got dealer reflashed to ditch SCT Tune (drove fine, just VERY edgy and aggressive at PT), loaded new CAI/LTH tune, and immediately something seemed off. Cruised home fine but with intermittent roughness and soft throttle response only driving lightly.
EQ Commanded goes very rich and lean in oscillating waves for seemingly no apparent reason. EQ Actual reacts slowly and seems to spend a lot of time being opposite.
We learned shortly after that the car from previous owner deleted IMRC pods from back (though not seeing usual Delete kit, just missing).
- Made initial IMRC Disabled / Open changes - car would not stay running.
- Added some Gen 2 logic to the MPs and VCT tables, same - would not stay running.
- Changed to just IMRC Disabled and turned off related DTCs, car ran fine-ish for very short test drive but EQ issue remains.
Is this just IMRC tuning challenges? Would this cause the EQ Cmd to fluctuate randomly even with DTCs off? No other work has been done on the car between a decent SCT tune and the Dealer stock reflash.
Here are 2 logs (initial dealer driver and short spin) and stock file with CAI and LTH mods.
I don?t think it is the IMRC delete alone because it?s actually driving just fine off idle and Part Throttle.
What else would cause EQ commanded to slowly drift down into .70 lambda range and as lean as 1.35 lambda? (All at idle, light load, and throttle inputs albeit) ?
Yeah, saw that on a Chevy, but it was bank to bank working against each other. In this case, it?s only actual versus commanded, and bank to bank stay together with only slight variances.
And, it seems to only happen at low loads, and not all the time. Will give it check all the same. Thx
IMRC's can be tricky to delete in the tuning, but the issue you're seeing with EQ cmd is due to poor MAF calibration. Your fuel trims are all wonky, especially at 500 ms period. See attached graph.trims vs period.JPG
Agreed but that is where the challenge was coming from, it was registering very inconsistent Trims with considerable swings both directions (pretty slowly I?d add) so the trims were averaging down into small numbers over time, so I suspect 500 had fewer cell hits for averaging and registered when it was in a lean mood? lol.
There was no confidence in moving the trims from the Transfer function beyond and blanket add.
The fickleness does diminish where low rpm is extra lean after startup but acts more normal after some driving.
I can now see that Commanded seems to be a more real time response to Trims rather than simply what the target is (as more typical in earlier generations.
Will continue to play with IMRC changes otherwise. Thx again.
Yes, eq commanded has the fuel trim added to the desired, so at a fuel trim of 30% it would be 1.3 commanded eq ratio. The maf flow is the same way. If you want the actual airflow you have to divide out the fuel trim (Assuming your injector data is accurate).
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