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Old 08-07-2018, 05:05 AM   #1
105Charlie
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Default Electrical cutoff resets LH2.4?

Hi

I have a cutoff switch fitted to my B200FT converted volvo 343 and I've just read that disconnecting the power to the ECUs resets them? I assume this means every time I get in the car it needs to relearn and therefore runs less than optimally.

I can't find any further info on this so just looking for some confirmation!

Cheers
-Charlie
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Old 08-07-2018, 06:51 AM   #2
MadDog_945
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yep it resets on power cutoff
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Old 08-07-2018, 10:24 AM   #3
105Charlie
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yep it resets on power cutoff
foooooooooooook.

Well looks like I'll have to rewire it onto the constant side of the switch. On a standard engine with just a boost hike I'm guessing it won't affect much

Thanks for the quick response!
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Old 08-07-2018, 10:38 AM   #4
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yep it resets on power cutoff
Just to follow up on this, I'm assuming it would just be a single pin over to the live side to give it the constant? If so what colour/pin should I be looking for? Not sure on the year of the boxes so assume this might be a silly question.
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Old 08-07-2018, 01:29 PM   #5
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We'll stock 2.4 volvo cars have a 30 amp fuse that supplies power to the Fuel ECU constantly and that keeps the ECU from losing it's learned fuel requirements. Here there are no 343's ever sold so no clue where that fuse is or what harness your even running or even if 343's even came with lh2.4 stock.

You say you converted it. Did you convert the wiring harness to say a 240 lh 2.4 harness? Those have a 30 amp fuse in the 2.4 harness right by the battery or later ones after 91 have them in the fuse panel.

You say you put in a cut off switch. A cut off switch where to what? The main constant power to the ECU? We'll get rid of that and wire it up constantly then....
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Old 08-08-2018, 09:12 AM   #6
105Charlie
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Originally Posted by sbabbs View Post
We'll stock 2.4 volvo cars have a 30 amp fuse that supplies power to the Fuel ECU constantly and that keeps the ECU from losing it's learned fuel requirements. Here there are no 343's ever sold so no clue where that fuse is or what harness your even running or even if 343's even came with lh2.4 stock.

You say you converted it. Did you convert the wiring harness to say a 240 lh 2.4 harness? Those have a 30 amp fuse in the 2.4 harness right by the battery or later ones after 91 have them in the fuse panel.

You say you put in a cut off switch. A cut off switch where to what? The main constant power to the ECU? We'll get rid of that and wire it up constantly then....
343s never ran LH2.4 - swapped in the engine and wired up the ECUs using parts of the loom. Cutoff is from the main battery line to the rest of the wiring so cuts everything.

I will run the constant fuel ecu wiring to the live side of the switch via a fuse. Does the ignition box not need the constant as it doesn't learn?
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Old 08-08-2018, 11:04 AM   #7
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The EZK ignition box also needs a permanent feed to store learned adaptive stuff:

http://ipdown.net/jetronic.info/tiki...s+and+Diagrams
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Old 08-10-2018, 11:19 PM   #8
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curious, why would you need a switch to disconnect the battery? easier while working on stuff I guess, but for regular use?
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Old 08-11-2018, 12:25 PM   #9
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Quote:
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curious, why would you need a switch to disconnect the battery? easier while working on stuff I guess, but for regular use?
Racecars will have them for safety. Or maybe he has one for storage.
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