Joined: Nov 2016

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I was at the tuner getting my twin turbo setup tuned and when these Derale fans were turned on bank 1 would lean out on my dual wideband and on the tuners wideband.
this was condition at idle.
i am running a stock alternator 102 amp after an unsuccessful try with a truck alternator.
Both fans are wired to a fuse block that connects to the battery via 1/0 gauge and the alternator, as well as the drivers side battery post.
Has anyone seen a condition like this before?
I don’t know if I need more amperage or if I have a grounding issue. Everything seems to work fine just seeing this condition when the fans are on. When only one fan is on the bank still leans out, Just not as badly and as quickly.
i also did a battery relocate to the trunk when building this if that is good info.

Joined: Jun 2016

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From: Central Cal.

Joined: Sep 2007

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Joined: Apr 2002

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From: So.Cal.

Joined: Nov 2016

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I don’t believe the fans are on either air filter and they are pusher fans with filters over each turbo where the stock battery was and right next to the stock fuse panels under the hood.
i just ordered and put on a 175A high output alternator and that didn’t seem to fix the issue. Seems like both banks lean out to where the HTR on each of my dual wideband comes back on. Shut the fans down and my car on wideband goes to normal.
i used -0 gauge for a positive to a distribution block in the front and grounded -0 to a thick cast iron mount that holds exhaust that also bolts to the frame. Should I take that apart and clean and check it?
i have -4 AWG from alternator to the distribution block about 1.5 ft away and -4 from my distribution block to the fuse panel. This spans from the stock battery location down around the radiator and then back up to the fuse panel battery post.
i also used the 2 stock ground wires that connected to the battery in the stock position and bolted those to the holes in the frame that were there from the factory.

Joined: Apr 2012

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From: SF Bay Area

How are the wide bands configured? Is there 1 on each bank? Or is it possible bank 2 is also lean but undetected? If so, I would check fuel pump voltage and ground there as well. PCM voltage drop?

Joined: Apr 2002

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From: So.Cal.

Joined: Nov 2016

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[QUOTE=s30.hybrid;19960809]There is one wide band per bank and per turbo. I just ran the car again with a new 175 amp alternator and both banks were going lean.