Temp Sensor Mod

Courtesy of Keman

Disclaimer:
This mod is for the hard-core creative types out there. Don't bring your car into the dealer with this mod in place, as they can legally void the warranty on your Computer, Wiring harness, and probably your ENTIRE engine. Run premium fuel only, and if you hear your engine pinging at any time after this mod, use a smaller capacity resister, or eliminate the modification entirely.

As some of you might have noticed, your ZX2 tends to be fairly weather dependant on it's scale of performance. Hotter weather means less dense air, and less fuel can be mixed with the air charge, and less power ensues. Plus, you turn on the A/C, which draws a good load on the engine. Luckily, when you stomp your foot to the floor to pass the mini-van owner who thinks that the papers in his glove-box are the deed titles to the fast lane, the A/C will disengage until you let off. Smart idea, Fords famous for it in their EEC-IV and EEC-V computer setups. One thing that did surprise me, is this little sensor shown below. It's an air intake temperature sensor. Now, the pic you see, is what MY sensor looks like. Notice the splice and the resister wired in? What's that? Your grinning wanting to know what I did... alright. =)

It's really simple. Give the above sensor a good tug and it will slide out of the big black air intake tube. Take a good look at it. If you hook an ohmmeter up to it, you will find that depending on it's temperature, it will read anywhere from 20K ohms (at about 90 degrees) to 35K ohms (at about 60 degrees). It measures the temperature of the air going into the ZX2. The PROBLEM... is that chances are if you've been running your car for a while- when you go to pull this sensor out, it, and everything else under the hood, will be around 110 degrees, or more. The computer listens to this sensor when determining how much ignition advance you should get. Given that your running 87 fuel. (hey, don't laugh, it's the computers default) it doesn't give a whole lot of advance. And there is plenty of room for advance if your running 92 gas. (Lets take advantage of some of that room) That combined with the overly hot conditions, means a real lacking for ignition advance. No wonder a superchips replacement chip with advanced timing did so well on our engine. Visit www.superchips.comfor a nice $200 chip which does a lot more than what this mod does. Now for some information I should explain for the heck of it:

Pinging, or predetonation, will occur with too much ignition advance and too little an octane figure. Pinging/Predetonation, is where the flame-front of the explosion in the cylinder strikes the piston as it's coming up, forcing the piston to compress the entire explosion. This is "bad". It will start out by destroying your piston rings, then bend rods, and finally punch a hole right through the piston, as I've seen when people run nitrous and don't let off when pinging occurs. You try compressing an explosion at 6000 rpm some time. Good luck.

On a normal engine, even on your engine, the spark plug fires before the piston is at top dead center, but.. the explosion is slow enough that the piston reaches "Top Dead Center" before the explosion wave hits it. Timing advance, fires the plug before the piston is at TDC, but sooner. And sooner. The faster the piston is moving up and down, the more the timing must be advanced to keep up, so that the explosion isn't happening while the piston is already travelling down. Gasoline only burns so fast. Octane, is a measurement of the volatility of fuel. The lower number, the more volatile it is, and the faster it explodes. So if you fire the spark plug too soon, with too low of an octane figure, the explosion wave will head towards the piston too quickly, and bam... "PING PING PING"... So the key, is to advance the timing just to the verge of pinging. The key really, is to run the timing to the type of fuel your using. But ford didn't design the ZX2 to run on Ultra-94 or Premium 92. With this mod, you can run that grade of fuel, and REALLY see some good results. Don't run this mod with 87 gas. =)

Stick a 5K ohm 1/2 watt, 5% tolerance resister (see: Radio Shack) INLINE with the temp. sensor, and it will force the computer to take into account the fact that everything under the hood is hot- but the air going into your ZX2 is not. The car springs to life, throttle response becomes very crisp, and the ZX2 pulls much harder and more reliably... with less atmospheric effects. I'm running a 10K ohm resister inline myself for even more ignition advance. So far, no problems. I used a "Two Position terminal block" available at your local radio shack for $2.19 US. to splice in and allow me to put a resistor in and not have to solder anything, and allow me to swap in new resistors very easily. The wiring block is two pieces of metal, each piece has two screws on it. Surrounded by plastic separators. Take off some of the electrical tape going to the sensor, cut one of the wires, strip it, put one wire on each side of the block. And "connect" the two terminals on the other side with the resis tor.

For now, it's just hanging there. When I find that a 10K ohm resistor doesn't give me any problems in a couple weeks I'll remove the block, solder the resistor in-line with the wire, and wrap it back up with electrical tape. Poof, I appear stock, and I bet the dealer would never even notice it even if they looked for it.

If you have any questions on this mod, or would like to attempt it yourelf, I'd be more than happy to answer them or help you.

- Keman