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Cold start driveability question

 
Old 02-27-2018, 07:54 PM
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Default Cold start driveability question

What is the stock 2001 LS ecu doing in this condition, and how can I fix it?


Driving after a cold start until the car warms up a bit, I get hesitation and bucking between 2,000rpm and 3,500rpm and in part throttle. If I give more than ~50% throttle, or go past 3,500rpm at any throttle position, normal acceleration occurs.


Other info

-This happened even when the car was 100% stock, and had no CEL.

-This does not happen after the oem temp gauge reaches around halfway to vertical position.

-This does not happen if cold starting in 50*F or hotter weather.

-This also did not happen at all while using an MS3basic unit.
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Old 02-27-2018, 08:03 PM
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It's doing exactly what it does.

Mine is the same way.
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Old 02-27-2018, 08:09 PM
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So this is a normal condition? It is super annoying, I don't like giving a cold engine lots of throttle just to accelerate normally.
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Old 02-27-2018, 09:56 PM
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Mine did this for a while, and then stopped. It doesn't make sense, but the only thing I changed was the battery...magically went away.
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Old 02-27-2018, 10:02 PM
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On further reflection, I'm fairly certain it has to do with the VTCS operation. I spent a long time messing around with it, even unplugged the VTCS solenoid, but that didn't fix it (made it worse actually). It was literally exactly what you describe, though, down to not happening above 50 degrees ambient. It went away after changing the battery, and was gone for over a year before I went to MS3.
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Old 02-27-2018, 10:39 PM
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Hm. I actually switched to a flat top as my first mod, because I though that would help. made no difference. I hate it so much, it's maddening.

I have had two different batteries, a stock replacement, and a Deka 14 pounder, no change.
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Old 02-27-2018, 11:06 PM
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I remember reading about the air temp sensor (in the airbox) fail but not badly enough to throw a code doing some weird stuff. Disconnect it, see if it changes - it probably will throw a code, but it might run better if it's getting bad readings.
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