2015 Vortech GT poor idle quality - Ford Mustang Forum
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post #1 of 4 (permalink) Old 02-12-2019 Thread Starter
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2015 Vortech GT poor idle quality

I have a 2015 Gt with a Vortech supercharger, Pypes off road headers and a Lund tune. it runs and drives great. When it gets colder than about 30 degrees the idle drops from a steady 750rpm down to a stumbling 650rpm or so. It only happens when it's cold. I checked the blow off valve and it seems fine, all connections seem tight.... I'm mot sure what it could be. Any ideas what I should check?

2011 Black 5.0 GT/CS manual, Tech pkg, HID, Comfort pkg
1/4"wheel spacers, GT500 exhaust, AEM intake, BAMA tune, Amsoil

1995 5.0 cobra clone. BBK full exhaust, BBK intake, 70mm throttle body. (sold)
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post #2 of 4 (permalink) Old 02-13-2019
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Is this a new development or has it been present awhile. How long?

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post #3 of 4 (permalink) Old 02-13-2019
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just a SWAG -- but it could have something to do with the Mass Air Flow (MAF) "transfer function" in the tune. The MAF sensor is supposed to send a signal to the computer that tells it how much air is coming in; and those readings can be affected by the temperature of the incoming air, because of how the sensor actually works. The tune defines some math, aka "transfer function" that is used to convert the readings to mass of incoming air. I'm guessing the low incoming air temperature might be throwing off that math.

Based on that guess, a phone call to Lund to describe and discuss the problem, might shed some light.

| 2010 GT coupe | Daily Driver with some Steeda and GT500 take-off stuff for the occasional track day
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post #4 of 4 (permalink) Old 02-13-2019
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Like jbert said. I was kind of getting to that point. if you have been driving the car in this climate and this tune and never had a problem before then that’s not it. if you just started this climate or just got this tune and that’s when it started then It can definitely be tuning
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