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serialk11r · 06-13-2015, 03:53 PM

Good news, everything I tuned seems to work as intended!

I probably burned a third of a gallon testing this but it'll pay for itself in no time. Turns out the OFT throttle map completely sucks so that's going to be some work to fix.

So first, lower idle speed. It works totally fine, but the problem is the second I turn the fan on it bumps back up to 700rpm. I believe the ECU targets 14V from the alternator and the engine is only barely capable of producing 14V to power the basic electronics around 600rpm. If I switch on the headlights or fan, then the voltage drops momentarily to 13.9V and then the idle goes back up to 700. 550rpm is about the limit in terms of driveability, the engine runs reasonably smooth but there's noticeable hesitation and vibration when you stab the throttle to rev the engine back up, I may increase it to like 575 target because it seems like there's diminishing returns.

At 550rpm stoichiometric, the fuel flow rate goes down to about 11cc/min, or 0.174gph

(BTW I think I made a wrong calculation earlier in the thread when I said the engine idles at 0.17x gph, it was like 13cc/min which works out to ~0.20gph.)

Even better news is that when I switched to the lean burn map, the fake fuel flow rate only barely went up and the MAF reading was still around 2.1g/sec (fluctuating of course but it might have gained 0.1 on average), meaning the lean idle is saving me at least 5% fuel!

I then tried turning the AC on. At 700rpm AC on, the MAF reads about 3.2g/sec stoichiometric, but on the lean map it also reads 3.2g/sec! The lean map then basically does not require any more airflow, which is amazing.

Did 2 7000rpm pulls in 1st gear, it's still very smooth, although like I said my tank currently has 25% ethanol so there shouldn't be any knock. I'm going to keep the 600rpm idle + 1.1 lambda map on my car and dilute the tank with 87 gas to get some more data. I need to log the car on the freeway to see if the cat temp is okay and how much mpg I picked up, but I have a good feeling that I'm already at my 45mpg target

06-13-2015, 03:53 PM	#23 (permalink)
serialk11r Master EcoModder Join Date: Jan 2012 Location: United States Posts: 1,756 spyder2 - '00 Toyota MR2 Spyder Thanks: 104 Thanked 407 Times in 312 Posts	Good news, everything I tuned seems to work as intended! I probably burned a third of a gallon testing this but it'll pay for itself in no time. Turns out the OFT throttle map completely sucks so that's going to be some work to fix. So first, lower idle speed. It works totally fine, but the problem is the second I turn the fan on it bumps back up to 700rpm. I believe the ECU targets 14V from the alternator and the engine is only barely capable of producing 14V to power the basic electronics around 600rpm. If I switch on the headlights or fan, then the voltage drops momentarily to 13.9V and then the idle goes back up to 700. 550rpm is about the limit in terms of driveability, the engine runs reasonably smooth but there's noticeable hesitation and vibration when you stab the throttle to rev the engine back up, I may increase it to like 575 target because it seems like there's diminishing returns. At 550rpm stoichiometric, the fuel flow rate goes down to about 11cc/min, or 0.174gph (BTW I think I made a wrong calculation earlier in the thread when I said the engine idles at 0.17x gph, it was like 13cc/min which works out to ~0.20gph.) Even better news is that when I switched to the lean burn map, the fake fuel flow rate only barely went up and the MAF reading was still around 2.1g/sec (fluctuating of course but it might have gained 0.1 on average), meaning the lean idle is saving me at least 5% fuel! I then tried turning the AC on. At 700rpm AC on, the MAF reads about 3.2g/sec stoichiometric, but on the lean map it also reads 3.2g/sec! The lean map then basically does not require any more airflow, which is amazing. Did 2 7000rpm pulls in 1st gear, it's still very smooth, although like I said my tank currently has 25% ethanol so there shouldn't be any knock. I'm going to keep the 600rpm idle + 1.1 lambda map on my car and dilute the tank with 87 gas to get some more data. I need to log the car on the freeway to see if the cat temp is okay and how much mpg I picked up, but I have a good feeling that I'm already at my 45mpg target Last edited by serialk11r; 06-13-2015 at 04:04 PM..