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14.7+ AFR for idle with a Turbo? EGO Temp Sensors?

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14.7+ AFR for idle with a Turbo? EGO Temp Sensors?

Old 11-28-2018, 04:06 PM
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Lightbulb 14.7+ AFR for idle with a Turbo? EGO Temp Sensors?

Why is it not okay to run normal 14.7 to 15.7 AFR's at idle and low load cruise with a turbocharged engine?

What I've gathered is you run the risk of increasing exhaust gas oxygen temps, which in turn can harm the turbo and shorten it's overall life-span.

I currently have a Flyin' Miata 2.5" turbo downpipe the 1st bung from the turbo is a regular o2 sensor and the furthest bung away from the turbo is where my AEM wideband O2 is located (You can imagine my lamba delay signals are about 5 to 8) . On tuner studio, it has 2 readings for EGO temp sensors, so I assume TunerStudio is thinking my O2&WB sensors are EGO temp sensors (Are they able to read EGO temps too?) but the readings don't seem to be accurate. For example 1 of them never shows less than 1400, even at cold start. And doesn't go past 1477 or so. And the other one always says like 1778-1787, without ever going below or above that range.

Ultimately, I'm wondering if O2/WBO2 sensors can read EGO temps for megasquirt tuning. Because I'd like to bring the AFR's (fuel consumption) to mimic more of a OEM fuel map while out of boost. The turbo is a little laggy anyway it's a GT2871R ebay replica. So if this is safe, this would be very beneficial to gas mileage. Rather than idling at 12.5 just because I have a turbo.

If anybody could explain the dangers of this to be with some detail it would be awesome. Thanks and happy holidays
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Old 11-28-2018, 04:25 PM
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I haven't heard anyone say that those AFRs are not ok.

Your wideband sensors are not EGT sensors.

You should probably set up your ecu properly.
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Old 11-28-2018, 04:29 PM
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It is okay if the engine is happy. I ran ~15.5-16 idle and cruise. Spark likes to be advanced a bit the leaner you go. There are very little differences to a turbo engine out of boost and a N/A engine. Not sure why you're idling at 12.5.

Post a log of this "EGO temp". Unless you're using a CAN wideband that broadcasts temp, most O2 controllers send AFR data over a 0-5V signal wire.
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Old 11-28-2018, 04:41 PM
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EGO stands for Exhaust Gas Oxygen. It is not a temperature, nor is it related to EGT (exhaust gas temperature) in any way.

Your car will idle just fine at 14.7:1.

No offense, but your post indicates a lack of understanding of even the most basic functionality of ECUs and O2 sensors. Until you are up to speed on the basics, I would advise enlisting the help of a professional.
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Basically I've come over to the camp of "If something is a reliability problem on the track, just ask Andrew and do what he says".
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Old 11-28-2018, 04:53 PM
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lol, just check his other posts.
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Old 12-07-2018, 05:30 PM
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Hmmm Okay. Here's another question. If you can run normal NA AFR Target values for a boosted car, while under 100kPa, Can you do the exact same for ignition?
Like in example, can I grab the www.megasquirtpnp.com 94-95 NA tuner base spark map and blend/round the numbers that are 100kpa or less and put them into my turbo spark map, and expect the same drivability and longevity/reliability as just using the original spark map. Yes or No and if so, how come?

I know this sounds like a stupid obvious question, but for some reason, every thing i've read and watched up to this point, and learned from, has always made it clear that you can't and shouldn't do that...|

But if I CAN, then shiii... It'd be NICE having that extra ign advance in the off-boost map... It would definitely add some kick in there, until I can afford a authentic dyno day, from all this street tuning.

Edit: Nevermind ,looking back at this, this truly was a dumb question. Ya'll can move on. Do not mind me

Last edited by NASSEX; 12-07-2018 at 07:33 PM.
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Old 12-07-2018, 10:19 PM
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Yes. Absolutely.
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