Electrical Problems in Rain

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This is a fresh build.

Im having some electrical problems and they get more serious when driving in the rain, Like everytime I turn my heater motor on or off while dataloging...It will lockup the s300 and Im then forced to restart it by shutting the car off and then back on for it to work again. I drove the car once in heavy rain and all my electronics went haywire....Like when I would turn my windsheild wipers on the gauge cluster would completely cut out, Then if I turned them off it would come right back.

The rain also affects the way the car runs....It would lean out hard and then go back to normal and repeat, Keep in mind everything on this engine is new.

I feel like the electrical problems may be a grounding issue but thats just a guess, I need to resolve this issue over the winter so I can get the car tuned in the spring.

Here's all the info I could think of off hand.

1997 Honda Civic DX Hatchback
B18A1 Bottom
B16A2 Top
CTR Cams
Skunk2 Intake Manifold
Blox 66mm Throttlebody
Magnecor Plug Wires
Timing is 16 Degree's BTDC
New Map Sensor
AEM Wideband o2
AEM Short ram air intake
New Blox TPS Sensor
Blox FPR
RC 310 Injectors
LS Stock Fuel Rail
OBD2A To OBD1 Conversion Harness
Hondata S300
Aftermarket Crank Pulley
99' SI Gauge Cluster
New Heater Core
No radio connected

Just about every seal in the car leaks water when its raining.

400 Watt power inverter hooked directly to the battery,Those wires do run parallel with the engine wire harness coming through the firewall into the cab. (It has a manual power switch)

EVAP Purge Control Solenoid Valve bypassed.

Dash is Not Completely Put Back Together, Still some wires hanging around for things like the lighter.

My rear defrost doesnt work, I havent tested to see if its getting correct voltage.

Previous owner removed rear window wiper, No idea if those wires are still just hanging out touching somthing they shouldnt be.

Oil and Wideband Gauge power are tied into an ignition wire that comes up to the ignition module (Where your key goes).

The mass ground for the vehicle is bolted underneath the passenger side dash to the sub frame, But there is paint there...Its not bare metal.

All paint under the hood is new, So all grounds under the hood are also touching paint..Not bare metal.

Any help is greatly needed and appreciated.


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I had also read some posts with similar circumstances, where the ICU under the dash had gotten wet from the windshield seal leaking water onto it.

You guys think thats a possability?
Well its not going to be wet, The car has been in storage for 3 months...I just dont want to wait until im driving the car in a big rain to track down the problem.

Im looking for people who have experienced somthing similar to this and what they did to fix it.
Also check those wires that are hanging around the dash. They might be grounding or when they aren't supposed to or vice verse
once had wires coming in threw the firewall and water was flowing down them near the ECU, caused the car to stall out a few times :p
I had that problem in my camaro once it was under my pass. fender and there was a little tiny wire exposed and it was jumping off stuff when it was raining or I hit a big puddle
My engine would cut out sounded like a shotgun gauges would go crazy
bad grounds will cause the wierdest sh*t. also make sure the tube that drains condensation (and any water that gets through ur fresh air flap) from ur heating/air conditioning unit is connected, or you'll get moisture all around the passenger floorboard.
your valve cover doesnt look grounded and redo all grounds they need bare metal it aint truely grounded on paint
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