I just wanted to throw out a 'heads up' regarding something I found on my otherwise pristine car.
A bit of background...
My car was bought and driven in Houston, Tx for the first 10 years of it's life so it's no rust belt baby. Back in Houston, I ran a nitrous kit and routed the nitrous line through the PCM wiring harness grommet beneath the PCM. Nice and clean. Later on (2007) I put a Turbo charger on and routed the Vacuum/Boost gauge through the same grommet along with various wires for Line Lock, Manual fan switch, etc. This really crowded the grommet and it didn't really fit well in the hole in the firewall but , "oh well" thought I....

The other day, I was under the car working on replacing my clutch and while under there, to my horror, I saw several rust through holes in the passenger side floor board, right where the floorboard starts to merge up to the firewall. Cussing, I got out my electric wire brush and scuffed off the areas paint, primer, etc then painted it with POR 15 (Paint over rust). This was just to stop the immediate rust from flourishing. Then, two days ago, I pulled up the carpet in that area. Damn it... There's a black plastic piece that floats above the firewall with foam on the back of it, I suppose for sound deadening purpases. It was as saturated with water as a kitchen sponge in a restaurant. The entire area beneath was wet and rusted out even worse than I expected based on the view from under the car. The ONLY way that water could have gotten in there was from rain/carwash water coming down the firewall and entering where that grommet was. There was no real indication inside the cab of the car that the carpet was continually saturated because of the rubber backed factory floor mats 'hid' the condition.

I just want to tell you guys that have routed stuff through that grommet to have a look at ..
a. The grommets sealing
b. The floorboard beneath the carpet in the passenger side.

I don't want to see you guys run into this hard to fix situation without being forwarned.

I've since sealed that grommet area. I've also sanded down the entire interior area, placed fiberglass mat (from a fiberglass mat patch kit) there. Sanded it all down after it dried and painted it inside and out with more POR 15.

 

Good heads up...I drilled a hole up high on the driver side of the firewall not to far from the oil pressure sender area. Haven't seem to have any issues from putting it there.

 

Thanks for the consideration Dave!

 

I had the same problem when I ran my SLP fan switch through there.

 

when my nitrous line ran in that hole same issue. wet all the time and it smelled. so i fixed that real quick