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Old 12-17-2015, 02:13 PM   #1
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Default Gas mileage?

MSM bolt on, stock turbo, rx8 injectors, ms3

My wife has been driving this car in town (to and from work really) but no highway driving.

For some reason, she cannot get past 14 MPG's. It has to be an issue with my tune. I haven't really rode with her while she's driving. But I'm pretty sure even with bad driving, she should at least be getting 16-18's.

Before, she was getting 16 though, which was still bad, but man there has to be something else.

I've attached my tune, and she mainly just drives in town, so like the top speed is like 50.

Also, I don't know if this is the current tune. I don't have my tuning ECU on me at the moment, but I'm pretty sure it hasn't changed. I feel like I should add a bit more timing down low according to this tune.
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File Type: msq CurrentTune - Copy (2).msq (212.9 KB, 142 views)
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Old 12-17-2015, 02:19 PM   #2
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I'm at work so can't open your tune, but aside from the blatant/obvious stuff like leaning out the AFR target table, making sure your car actually hits the values it's triggering, making sure you're not warming up too rich, you'll also need to focus on the transients, so AE and EAE, since a lot of fuel is wasted in around town driving when the car is constantly pegging rich on throttle lift or throttle snap.

IIRC my MSM got 19-22 on E85 and about 22-26 on pump gas, all city driving just like you. On ID725 injectors.
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Old 12-17-2015, 02:29 PM   #3
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Okay, I'm going to have to steal the miata back. I do remember not getting AE dialed all the way in.

I mean what are the chances of her driving is so poor that she's getting terrible mileage?
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Old 12-17-2015, 02:52 PM   #4
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My experience is same as 18's. My commute is half lots of traffic lights in 35-45 MPH zones, and half 55 MPH zones. I always drive for fun (meaning gas pedal hits floor often) and get 24-26 MPG tank after tank.Car is presently about 180 WHP configuration.
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Old 12-19-2015, 10:06 PM   #5
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I would imagine my milage is 12 to 15. I do floor it quite a bit.
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Old 12-20-2015, 12:54 AM   #6
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A tune file doesn't help. We need a log.
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Old 12-20-2015, 12:16 PM   #7
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Driving like a cizilived human being, I get as much as 26mpg out of my build on 93. Spirited closer to 20-22. Haven't driven hard enough to calculate how it does as WOT over an extended period.
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Old 12-20-2015, 01:11 PM   #8
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Okay, so I started driving the miata today since my wife was off work. I realized what is going on. I adjusted the IAC a little to get the idle down a little lower, and noticed the wideband would go completely lean. I started adding fuel, and it would still go lean. The motor would obviously bog rich, but no change on the gauge.

I moved the iac back to where it was (roughly), and reverted back to the old tune before i touched anything. And drove it around. The UEGo would sometimes go rich in between shifts, but mainly sat at lean. Car ran kinda strange. So i turned EGO corrections off, and viola. Car runs pretty decent again.

So I guess my aem uego took a ****. Or I sprang an exhaust leak. EGO correction was maxing it to the rich side since the gauge was reading lean.

But the thing about it, was this morning as it was warming up, the was reading normal. Then as the car went warm, it went to crap.

Is it possible that the gauge was in warm up mode, and as it actually got hot, the sensor no longer reads? i'm pretty positive the gauge doesn't work until the sensor is warmed up. The UEGO in my R32 is virtually the same as well, at first it just sits at 15, then as the gauge warms up (10 seconds or so), then it begins to read like normal
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Old 12-20-2015, 02:09 PM   #9
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Don't treat the wideband like gospel at idle. Just tune for lowest vacuum.
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Old 12-20-2015, 02:21 PM   #10
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I don't, but i treat it as is when i'm cruising and it only shows lean
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Old 12-21-2015, 04:20 AM   #11
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Not too long ago, a customer of mine complained that this UEGO would stop working after 5-10 minutes after installing a new sensor (but the sensor never actually worked again after that 5-10 minutes. It turned out he was given the old 30-4100 gauge (made for the older LSU 4.2 sensor) but the box had the 30-4110 wiring and LSU 4.9 sensor. I don't think your case is the same though.
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Old 12-21-2015, 05:50 PM   #12
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Yeah, that's weird. I don't know how to differentiate between sensors either. It's been a long time. I'm just going to order the 17014 and hope for the best.
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Old 12-22-2015, 01:52 PM   #13
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Sumbitch.

Mine is a LS4.9 sensor
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Old 12-28-2015, 01:08 PM   #14
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So here's an update, new o2 sensor went in. Added some more timing, and pulled some more fuel. I drove it for about a 1/4 of tank, and got about 60 or so miles. So much better, almost doubled in fuel economy.

So my thing is this, maybe the wideband was taking a dump, and since it had EGO correction on, it was just adding fuel nonstop.
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Old 01-24-2016, 09:23 PM   #15
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Just an update. I moved the car over to accel pump. I used 100% map. Not only does the car run sooooo much better. Today I drove to San Antonio and back. Finally am getting stock gas mileage! 250 to the tank! Before I did anything to the car, I could only get 220-230. And as of recently 160-180. I'm totally ecstatic
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Old 01-24-2016, 10:10 PM   #16
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Use TPS instead. It's miles better.
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Old 01-25-2016, 12:21 PM   #17
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I tried fiddling around with TPS based Accel pump, but couldn't make odds or ends of it.
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Old 01-25-2016, 01:40 PM   #18
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I use MAP based and X-tau stuff, never liked TPS based myself.
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