We have all heard the saying, “Timing is everything.” It’s absolutely true. Timing has an enormous effect on our lives. Walk into a restaurant on the right day and meet the love of your life. Idle in your driveway for 10 more seconds before you leave and avoid a head-on collision. The universe and the game of chance is a totally crazy concept. Most of it is completely out of our control. However, there is one sort of timing you can control and that is engine timing.
Timing a vehicle determines when each spark plug will fire during the rotation of the crank. It is crucial the spark plug doesn’t ignite while the piston is in the wrong position inside the cylinder. Getting engine timing just right not only ensures you don’t inadvertently harm your engine, but if the spark plug lights at the optimal moment, it can increase performance. Since we are all racecar drivers, performance is what we are looking for. Timing is a free way to get the most horsepower and torque possible.
For most vehicles, timing is adjusted by rotating the distributor clockwise or counterclockwise. By using a timing light aimed at the crank pulley, you can see where your timing is set, and add or subtract advance, the moment the spark plug lights prior to the piston hitting the top of the stroke. With computer-controlled vehicles, there are two types of advance. Mechanical advance — moving the distributor — and electronic advance, when the engine computer tells the coil to fire. To adjust the mechanical advance accurately using a timing light, it is imperative the ECU is not in electronic advance when you are making that adjustment. How do you know if the ECU is in electronic advance? You don’t.
On vintage Hondas, the factory provided an open connector in the wiring harness where you can insert a homemade jumper wire, which will ground the engine computer to tell it not to allow for electronic advance. This open connector is normally located in the right front foot well near the ECU. Accessing this location is troublesome, especially after you add a six-point roll cage. Trying to stand on your head and find this little wire and then try to connect a jury-rigged jumper wire or bent paperclip is not a good time. I knew there had to be a better way.
NASA NorCal racer Aj Gracy owns Performance In-Frame Tuning in Napa, Calif., and he helped wire our Honda Challenge car from the ground up. While we were designing the wiring looms for the car, we discussed adding a switch to the dash to replace the paperclip tool necessary to put the ECU into timing mode. The concept was simple, hard-wire two wires into the connectors where the jumper wire is usually temporarily placed, then connect the two wires to a switch on the dash. In one position, the switch would disconnect the wires — simulating the jumper wire being disconnected, allowing electronic advance — and the other switch position would connect the wires enabling the loop — electronic advance not allowed for mechanical engine timing.
We wired up the loop wires to a switch on the dash and labeled the switch for each of the two positions. Up was labeled “DIAG.” for diagnostics (loop engaged) and down was labeled “RACE” for full performance (loop disengaged). While we were at it, we added a supplemental check engine light next to the switch so if the ECU threw a code, we could decode that diagnostic trouble code by counting the number of times the light blinks. Yes, a 1990 Honda speaks its own version of Morse code for DTCs.
To quickly time our Honda Challenge car, all we had to do was flip the switch up to “DIAG.” and then connect a timing light to the battery under the hood, grab a 12 mm end wrench for the three bolts that hold the distributor in place and set the mechanical advance to around 12.3 degrees. While using a chassis dyno and adjusting timing and fuel pressure with a stock ECU, we were able to gain 3-to-8 horsepower. That may not sound like much, but in a series like Honda Challenge you take every ounce of power you can get.
Before we created our simple-to-use diagnostic switch, for years we used the paperclip method. Instead of a wire loop, we just jammed a paperclip into the wiring harness and hoped it was connecting to both sides and creating the ground we needed to turn off electronic advance. Now, instead of hoping and guessing if the connection is made, our switch works every time without a doubt.
Now when I get into the racecar, I look at my switches and ensure my diagnostic switch is down in the race position. On the radio, my crew chief will ask me while I’m on grid, “Race mode?” and I reply, “Yes, race mode on!” Then I know it’s time to go fast.
Adding a fixed switch to replace temporary wire loop was a simple idea we implemented to make our lives easier at the shop and at the track. Searching for a homemade wire loop or a paperclip in your toolbox and crawling upside down in the interior of a caged racecar just to ground the ECU to time a car is a waste of precious minutes. For a few dollars spent on wiring and a switch, we solved this problem and never looked back.