Search popular car performance websites and you'll probably uncover discussions on improving the grounding of a car's engine and associated parts.
There are wild claims about the results from doing this. Some people claims this does nothing. Others claim 5 horsepower and 19 foot pounds of torque. As with most things, the truth is probably in between.
However, there is a degree of logic that the modification can help the car run somewhat "better". Newer cars have a lot of electronics on them - lots of sensors to provide information to the car's ECU. If there's electrical noise in these signals, then the ECU *might* make poor decisions while adjusting things like fuel/air ratios, timing, etc. The ECU is the Engine Control Unit or a "computer" that's dedicated to making your car's engine run correctly.
In theory, improving the grounding reduces the resistance of the electrical path, and makes it more likely that the sensors, etc. will return clean information.
So, for $20 and a little wrench time, it's an easy mod to perform even if you don't really notice much difference in performance.
On my TL, I chose to "daisy-chain" the chassis, alternator, engine, throttle body and battery negative post together. You may decide to add or remove some of these locations.
Step 1: Obtain the Cables
I used four (4), 19" 4 gauge "switch to starter" cables for my grounding kit. I obtained these from Pep Boys for $4.50 each. Less than $20 including tax.
These cables come in a variety of lengths. Nineteen inches was the shortest I found, and forty the longest. These cables have plain terminals on both ends. These cables were only available in the ultra-sexy "Henry Ford" black. Doesn't really matter - you'll pretty much never see them - another reason not to spend lots of bucks for 'primo' cables.
Step 2: Remove Covers
Before you can do anything much on a TL, you need to remove the covers. The left and right covers simply pull off with an upward motion. The engine cover has 3 locks. These locks are rotated about 60 degrees counterclockwise to unlock them. The cover then lifts off.
Step 3: Safety First - Disconnect the Battery
You DO NOT want to short your car battery. Car batteries are capable of delivering hundreds of amps of current. While there is very little danger in being shocked - 12 volts is just not enough to overcome the electrical resistance of human skin - there is a VERY REAL danger of welding your favorite wrench to your car or otherwise damaging the car, tool or battery.
Be smart and disconnect the battery first!' This is another 10mm bolt.
Reminder: If you have a radio or other equipment that uses anti-theft codes, make sure you have them BEFORE disconnecting the battery! This TL has anti-theft codes for the radio and navigation system.
Step 4: Chassis Ground
I started with the chassis ground on the passenger side of the vehicle. If you look at the engine bay near the windshield washer fill, you will find a spot where Acura ran a ground cable from the engine to the body. This ground is secured with a 10mm bolt. Remove the bolt and add one end of one of the cables to the connection. Depending on how big the hole is in your cable terminal, you may want to add a washer to the stack.
Step 5: Alternator Ground
The chassis ground cable is run to the top of the alternator where a lovely bracket awaits an additional purpose in life. Remove this 10mm bolt and insert the 'other' end of the cable you just bolted to the chassis. You will also attach the engine cable here - so you have a stack of two cables you've added to the bracket bolt.
Routing of the cable from the chassis is not too critical, just run it so it doesn't rub hoses and is away from the belt.
Routing of the engine ground cable is "up", that is towards the rear of the engine compartment.
Don't tighten this bolt up yet, you may need to wiggle the cables around some for the best fit.
Add a washer to the stack if needed.
Step 6: Engine Ground
The engine ground cable that you just attached to the alternator is bent at a 90 degree angle to the right and run along bracket, under the coil wires. It easily reached the last bracket bolt on the driver's side of the engine. Again a 10mm bolt and the next cable leading to the throttle body is stacked. You can tighten this bolt up now - nothing much to adjust here.
Once this is in place, go back and tighten up the alternator bolt stack.
Step 7: Throttle Body
The throttle body cable continues its run from the engine toward the driver's side. It's then bend "90ish" degrees to the rear of the engine compartment toward the throttle body. The lower front throttle body bolt (12mm this time) is removed and the throttle body ground cable and final ground cable to the battery is attached. Be careful tightening this up as it is a steel bolt threaded into the aluminum manifold - no need to strip this out!
Again, route the cables sensibly and neatly!
Step 8: Battery Ground - the Final Link
The final link in the daisy chain is from the throttle body to the battery negative terminal. I removed the nut from the cable clamp and added the final cable terminal plus a washer (battery nut is fairly small). Once assembled but not tightened, put the battery terminal back on the battery (it will probably spark a little, don't freak) and tighten the assembly up. Again, run the cable neatly. The OEM battery ground cable runs about 6" to the chassis off the driver's side of the battery.
Step 9: Replace Covers and Crank Her Up!
Replace the covers and you're done. Crank up the car, enter your radio codes and any others and take it for a spin to enjoy... well, who knows what. If you think you get a real boost from this mod, I'd love to hear about it in the comments.