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Old 06-13-2015, 06:35 AM   #21 (permalink)
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Oh wow, I feel really stupid now. I couldn't open the stock ROM and just assumed the OFT tune was close. I then tried changing the extension and it worked. Turns out the OFT map runs richer in the midrange, and made some pretty bold VVT changes which I don't want to be throwing into the mix. Time to redo all my maps -_- I'll still flash these to test out the idle and lean burn, but if they work out I still need to redo everything.

Now that I am looking at the stock maps, it seems that my pulses were below 0.85 g/rev, but the engine would run closed loop enrichment anyways for god knows what reason. Maybe knock control, which I feel is pretty likely.


Last edited by serialk11r; 06-13-2015 at 06:40 AM..
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Old 06-13-2015, 06:38 AM   #22 (permalink)
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Old 06-13-2015, 03:53 PM   #23 (permalink)
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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

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Old 06-14-2015, 01:52 AM   #24 (permalink)
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Well, 9 hours of fiddling with tables later I get these nice smoothed out throttle maps (I did both maps because I couldn't figure out which one does what):



Time to give this a test drive!

EDIT: So other than the first bit of pedal travel feeling completely dead, I LOVE this throttle map. It's so easy and intuitive to get the right amount of power since I made the map actually use all of the pedal travel, and it's still responsive. I can hold the engine at any rpm I want with ease and the blips feel just like my cable throttle MR2. I'm rescaling the map a bit so I don't need to press as far down on the pedal to get power, but otherwise this is perfect.

I just tested a 16.8 AFR lean map and this one is a handful. Getting off idle is not a sure thing even at 700rpm, but it doesn't stall. I'm going to log this and swap to my VVT adjusted map to see if that one does any better. If not, I'll try more tip in enrichment. I'm not sure if I should be adding timing because it's already running kind of rough and adding spark advance would be attempting to light the mixture at a lower temperature, which doesn't seem good. Something to try for sure, when I get the VVT sorted out so I don't need to switch maps as many times.

At night it's easy to tell that the electrical system isn't doing so well below 600rpm, as the lights are constantly dimming.

The good news is that I filled a third of the tank with 87 and there's still no knock. I'm going to try a full tank of 91 next to see how that does on this map.

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Old 06-15-2015, 04:03 AM   #25 (permalink)
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Bad news, the 87 I added seems to be triggering some knock correction and reverting to the "safe" maps. Ignition advance multiplier is doing fine at 1.0, but I guess the car picked up a little knock or something. (EDIT: turns out "knock correction learn" refers to timing advance, so no knock, but my wonky fueling probably triggered the safe map?)

But even worse, the ECU seems to have figured out my lean burn shenanigans I was driving along the highway and was super happy to see the mpg meter around 41 at 60mph (so actually 46!), but then my mpgs started going down until they were even worse than the stock map after correcting for the reading difference. I glanced at my OFT and I could see the AFR going down until it stopped at 12.5!

I took the closest exit and reflashed the map. Same thing, car learns to idle at 16.8, then it starts running richer and richer. I think it's the post cat O2 sensor correcting the intentionally skewed readings coming from the front O2 sensors.

I've also decided that the weird engine behavior with a low idle target is a little too freaky with the nearly stalling and loss of electrical power. If I press the brake hard the engine stumbles, if I turn the steering wheel hard (electrically assisted) it also stumbles, and it keeps bouncing up to 700 and then down again. I'm going to try 600 for a bit and if I don't like it I'll go up a little more.

I've switched to a mostly stock map until I can review the logs in detail. That 41mpg carrot that got dangled in front of me has got me motivated, but I may have to physically cheat the post cat sensor to let the car run lean. Maybe 16.0 would be more acceptable to the engine and wouldn't trigger the enrichment.

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Old 06-16-2015, 05:32 AM   #26 (permalink)
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Alright I found some more tables that might do the trick:


Closed loop fueling compensation target. If "target" means anything close to what that word suggests then it should run lean. This should be much easier to log because the O2 sensor isn't being screwed around with as much. I added 1% to the O2 sensor reading for experimentation purposes (to see if the post-cat sensor correction happens again). Set the idle to 600rpm on this map, and made a 620rpm idle backup map if that idle still doesn't go well.

Made a couple more tweaks to the throttle mapping, I further sharpened the response overall to reduce the amount I'm stepping on the pedal and I also smoothed out the response at low rpm a bit more to try and get the revs to fluctuate a bit less on starts. Throttle response nirvana is near!
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Old 06-17-2015, 12:38 AM   #27 (permalink)
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Looked at the logs, turns out I'm wrong again and the ECU is still not cooperating.

First of all with VVT, I took out some exhaust cam retard thinking it would help reduce exhaust pumping loss and improve combustion quality, but it appears the EGR effect from having more overlap is extremely important for reducing pumping losses!

For 0.3g/sec mass airflow at 2600rpm or so (and thus, equal engine load), with intake at -10 deg advance and exhaust at 25 deg retard, MAP is around 6.0psi. With intake at 20 deg advance and exhaust at 35 deg retard, same load/MAF reading, MAP tends to be reading around 6.4 psi.

Setting the CL fueling target compensation tables made the engine run a little lean of stoich on the freeway but not anywhere I told it to.
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Old 06-17-2015, 12:57 AM   #28 (permalink)
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Enjoying the write up!!!

Sounds like your engine likes the extra overlap?

So is the ecu resetting itself??? Also is the A and B tables min octane, and high octane tables, based on low knock logs?
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Old 06-17-2015, 09:10 AM   #29 (permalink)
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Quote:
Originally Posted by pgfpro View Post
Enjoying the write up!!!

Sounds like your engine likes the extra overlap?

So is the ecu resetting itself??? Also is the A and B tables min octane, and high octane tables, based on low knock logs?
I imagine when there's 2 tables A and B that generally does refer to something like that, or maybe a normal and limp-home mode. I have no knock registered though, since my fuel has so much ethanol in it (on that note, one of the few E85 stations in the Bay Area is on the way home from work, conveniently).

It seems like fueling compensation target is more like a closed loop AFR fluctuation allowance meant for calibrating the fuel trims, since the AFRs are just all over the place at cruise now. I'm going to revert those tables and see how much O2 sensor scaling the engine will tolerate.

And I don't think the engine "likes" overlap, it can just take more of it You can find the development papers for the IS350's 2GR-FSE engine which mention how the new direct injection system allows 21% charge dilution with internal EGR, 2x as much as the MPFI engine. I'm going to revert the exhaust VVT maps and keep the intake retarded to -10 and see what that does. If it doesn't cause an increase in vacuum I'll keep that because less charge dilution is better for combustion. It is however possible that it'll increase vacuum because during overlap the higher pressure in the exhaust system can cause extra exhaust to blow into the intake tract, vs. just trapping more exhaust in the cylinder at the beginning of the intake stroke.
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Old 06-17-2015, 03:39 PM   #30 (permalink)
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