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NA-T SC300 out of storage. Drives well, but idles very lean

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Old 04-15-16, 10:37 PM
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myLEXsc400
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Default NA-T SC300 out of storage. Drives well, but idles very lean

So, I had my turbo sc300 in storage for the winter. I would occasionally start it up and drive it around the block a few times but it mostly sat. I took it out in march on a nice day, and all was great. Then I parked it again in the garage for another month without starting, and decided to take it out a couple days ago due to nice weather. Battery was completely dead, so i jump started it, pulled it forward out of the garage, and let it idle for about 10-15 minutes. It idled perfect, and a/f ratio was hovering around 15 to 16. when i got in the car to drive it, put it in gear, gave it gas and then coasted to a stop, the revs dropped and it started to idle weird and sputter a bit. The a/f ratio went full lean "---" and the car kept idling like this, so i turned it around and parked it back.

A couple days later (today) i decided to try the car our again. I decided to reset the ECU by pulling the 30 EFI fuse for a half hour. I also added 2.5 gallons of fresh 93 octane and half a bottle of octane booster (car was below a quarter tank and gas was about 4 months old I'd assume). Battery was dead again, so I jumped it and idle surged high, then hunted around for a bit and then started sputtering like it did before and idle was super lean, wideband reading "---" again. I then decided to drive it around for about 15-20 minutes, and the car drove great. No hesitation, linear power and good boost, but every time it went to idle it hunted for rmps, and sputtered again. Idle would range from 800-1200 varying every once in a while. Plus the car smells like fumes a lot.

What do you guys think it can be? Vacuum leak? I'm lost, and I'm not a mechanic, so don't know what to check. Any and all help appreciated.
Old 04-16-16, 10:44 AM
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emLEX
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Possibly your dead battery and poor alternator charging at idle?
Old 04-16-16, 07:28 PM
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CatManD3W
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Did you treat the gas....when it was stored......?

May have clogged up filter or injectors.

Try running some redline fuel system cleaner....Cost about $10....and it works awesome
Old 04-16-16, 08:11 PM
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BiGEZ
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If your battery went dead then your ECU is probably relearning the drive pattern. I recently disconnected my battery to install a head unit and had the same low/off idle for a bit. I drove it for about an hour and it cleared up. Drive it for a bit more and see if it smoothens out.
Old 04-17-16, 05:42 AM
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Studiogeek
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Originally Posted by BiGEZ
If your battery went dead then your ECU is probably relearning the drive pattern. I recently disconnected my battery to install a head unit and had the same low/off idle for a bit. I drove it for about an hour and it cleared up. Drive it for a bit more and see if it smoothens out.
+1! Same thing happened to mine ^

I hope that's all it is! :thumb:

It's gotta be basic!
Old 04-17-16, 09:26 AM
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t2d2
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Once you get this sorted out, invest $5 in a Harbor Freight battery tender for lengthy periods of storage. Your battery will thank you.
Old 04-19-16, 07:29 AM
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myLEXsc400
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Originally Posted by emLEX
Possibly your dead battery and poor alternator charging at idle?
Idk, usually if its poor battery or alternator charge then i would see lights trying to dim out or something, right?

Originally Posted by CatManD3W
Did you treat the gas....when it was stored......?

May have clogged up filter or injectors.

Try running some redline fuel system cleaner....Cost about $10....and it works awesome
The gas was originally about 5 months old when i took it out of the garage a week ago. It was at less then 1/4 tank. Then when i took it out again the next day i added 2 gallons of 93 octane and half a bottle of octane booster and drove it around for about 20 minutes.
I will check out the fuel system cleaner. Thanks!

Originally Posted by BiGEZ
If your battery went dead then your ECU is probably relearning the drive pattern. I recently disconnected my battery to install a head unit and had the same low/off idle for a bit. I drove it for about an hour and it cleared up. Drive it for a bit more and see if it smoothens out.
I had the battery disconnected last year when I stored the car for winter, and when I started it up it drove perfect. Nothing should have changed on the car since then, so idk why it would happen this time. I will drive it around again tomorrow, hopefully for a longer time.

Originally Posted by Studiogeek
+1! Same thing happened to mine ^

I hope that's all it is! :thumb:

It's gotta be basic!
Did it happen to your boosted car? What symptoms did your car experience?

Originally Posted by t2d2
Once you get this sorted out, invest $5 in a Harbor Freight battery tender for lengthy periods of storage. Your battery will thank you.
Yes, got one today actually. Now I just need to buy a new Interstate battery.
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