Toyota MR2 Message Board - View Single Post - mr2's. fires. ground potential. what you NEED to be doing to your car right now.

TomsMR2 · 02-15-2009, 07:15 AM

we've all heard stories about mr2's going up in flames! its heart breaking for the most part.. but the truth is, its very largely preventable!

many mr2s over the years have gone up in flames due to car fires.. sometimes its due to age, sometimes its due to poor mods and swaps. in this day and age its not uncommon to have a chassis with a completely different drive train in it. thats all fine and dandy, theres nothing inherently wrong with swapping drivetrains.

however, the grounds on these cars are CRITICAL.

as most of you know.. mr2's have a battery in the front of the car, in what we call the "frunk". this is the main power source for all critical power. while great for weight balance, this can create a problem with providing high amperage draw circuits, such as the starter, with an appropriate ground path.

a lot of people dont understand what "ground potential" is. to simplify the concept.. a ground is a ground is a ground is a ground. a ground wire from the negative terminal to the chassis is just as good as a ground from the negative terminal to the engine block, or the transmission.

what happens in an engine.. the engine block grounds itself to the head via the studs, the engine block grounds itself to the transmission because it physically touches metal to metal, and is bolted securely. because of that, the head is equally grounded to the transmission, through the block, and vise verse. this is called "ground potential". since all components are jointed, very securely, though a LOT of metal, they all have the same potential to carry electricity back to the battery.

they just need a something between them, and the battery to carry electricity!

this makes all those components good grounds! toyota knows this and has provided a simple ground strap from the chassis to the transmission.. a connection more than adequate to be safe and secure.

what happens is that people do swaps, or just old age kicks into effect, they leave that critical ground loose, or connect it poorly, or get corrosion between the points. electricity still does its thing and finds another path back to the battery.. usually through the throttle cable, or other greased, highly flammable lines! this causes fires almost every time!

the end result is a bad fire.. all because of one, very simple connection missing... the ground back to the battery.

so whats this mean to you? this means YOU can prevent your car from electrical failure and fires.. extremely easily, and cheaply! everything electronic in your car will last longer if you put effort into your ground system. i seriously havent even changed a single light bulb in my car in 7 years.. secure grounds make secure components.. and secure components last longer, give better fuel economy, and run smoother.. not to mention safer.

so to the meat and potatoes. in your frunk, connect a thick wire, 8ga or lower is good.. from the negative terminal to ANYWHERE in your frunk. theres multiple threaded holes, choose any of them. sand the paint off before you make the connection, you can apply dielectric grease (sold as "spark plug grease" at autoparts stores) to prevent rust. now clean up the existing factory ground wire too, sand down that connection and apply grease. this gives a good metal to metal ground in the frunk.. which grounds your battery to the entire chassis.

now your WHOLE chassis is a very good, reliable ground! lets move to the engine.

toyota provided us with a good ground here again.. but lets freshen it up. they're old cars now, corrosion happens! remove your airbox (na's and turbos have it in the same location, its applicable to both). you will see a black, fat wire connected under it. unbolt that connection and sand off wire terminal, and sand the chassis where it bolts to as well.. again apply grease.

this really covers you for most things.. but lets take it a step further. this is VERY cheap insurance against many, many problems.. buy another ground wire from the autoparts store and connect it to your engine. you can use any hole on your engine, transmission, or cylinder head. again, theres a bunch of pre threaded holes to use, connect it to any of them. since youve already grounded your chassis to your battery, any part of the frame becomes an excellent ground!

you've created what toyota calls "redundant grounds". they're just safety backups, just in case. modern toyotas have already done these steps for you because it makes reliable cars.. it creates an equal ground potential throughout the car.

this might cost you 15 or 20 bucks in wires, and 15 or 20 minutes of your time. but it WILL save cars!

lets not see any more lost projects this year!

02-15-2009, 07:15 AM	#1 (permalink)
TomsMR2 Formerly Tom Brokaw Join Date: Feb 2005 Location: Bay Area Posts: 2,497 Thanks: 8 Thanked 233 Times in 168 Posts Blog Entries: 1 iTrader Rating: (0/0% )	mr2's. fires. ground potential. what you NEED to be doing to your car right now. we've all heard stories about mr2's going up in flames! its heart breaking for the most part.. but the truth is, its very largely preventable! many mr2s over the years have gone up in flames due to car fires.. sometimes its due to age, sometimes its due to poor mods and swaps. in this day and age its not uncommon to have a chassis with a completely different drive train in it. thats all fine and dandy, theres nothing inherently wrong with swapping drivetrains. however, the grounds on these cars are CRITICAL. as most of you know.. mr2's have a battery in the front of the car, in what we call the "frunk". this is the main power source for all critical power. while great for weight balance, this can create a problem with providing high amperage draw circuits, such as the starter, with an appropriate ground path. a lot of people dont understand what "ground potential" is. to simplify the concept.. a ground is a ground is a ground is a ground. a ground wire from the negative terminal to the chassis is just as good as a ground from the negative terminal to the engine block, or the transmission. what happens in an engine.. the engine block grounds itself to the head via the studs, the engine block grounds itself to the transmission because it physically touches metal to metal, and is bolted securely. because of that, the head is equally grounded to the transmission, through the block, and vise verse. this is called "ground potential". since all components are jointed, very securely, though a LOT of metal, they all have the same potential to carry electricity back to the battery. they just need a something between them, and the battery to carry electricity! this makes all those components good grounds! toyota knows this and has provided a simple ground strap from the chassis to the transmission.. a connection more than adequate to be safe and secure. what happens is that people do swaps, or just old age kicks into effect, they leave that critical ground loose, or connect it poorly, or get corrosion between the points. electricity still does its thing and finds another path back to the battery.. usually through the throttle cable, or other greased, highly flammable lines! this causes fires almost every time! the end result is a bad fire.. all because of one, very simple connection missing... the ground back to the battery. so whats this mean to you? this means YOU can prevent your car from electrical failure and fires.. extremely easily, and cheaply! everything electronic in your car will last longer if you put effort into your ground system. i seriously havent even changed a single light bulb in my car in 7 years.. secure grounds make secure components.. and secure components last longer, give better fuel economy, and run smoother.. not to mention safer. so to the meat and potatoes. in your frunk, connect a thick wire, 8ga or lower is good.. from the negative terminal to ANYWHERE in your frunk. theres multiple threaded holes, choose any of them. sand the paint off before you make the connection, you can apply dielectric grease (sold as "spark plug grease" at autoparts stores) to prevent rust. now clean up the existing factory ground wire too, sand down that connection and apply grease. this gives a good metal to metal ground in the frunk.. which grounds your battery to the entire chassis. now your WHOLE chassis is a very good, reliable ground! lets move to the engine. toyota provided us with a good ground here again.. but lets freshen it up. they're old cars now, corrosion happens! remove your airbox (na's and turbos have it in the same location, its applicable to both). you will see a black, fat wire connected under it. unbolt that connection and sand off wire terminal, and sand the chassis where it bolts to as well.. again apply grease. this really covers you for most things.. but lets take it a step further. this is VERY cheap insurance against many, many problems.. buy another ground wire from the autoparts store and connect it to your engine. you can use any hole on your engine, transmission, or cylinder head. again, theres a bunch of pre threaded holes to use, connect it to any of them. since youve already grounded your chassis to your battery, any part of the frame becomes an excellent ground! you've created what toyota calls "redundant grounds". they're just safety backups, just in case. modern toyotas have already done these steps for you because it makes reliable cars.. it creates an equal ground potential throughout the car. this might cost you 15 or 20 bucks in wires, and 15 or 20 minutes of your time. but it WILL save cars! lets not see any more lost projects this year!