No Cost Performance Upgrades to a ZX2...

ZX2 Dedicated Discussion Performance Modifications
1

Looking for free power improvements? Here’s a few suggestions…

  1. Weight Removal - dump out any items from the interior or trunk that you deem inconsequential since 15lbs of weight equals 1hp of added power approx. Gas mileage goes up too. I usually remove the spare, jack, false floor, and carpet from the trunk for less weight and added trunk space when i need it. I’ve never had a flat on any of my zx2’s so to me a can of tire sealant and a aaa card make more sense. Newer cars with the tire pressure sensors are starting to delete spare tires from their trunks as well. If you don’t have rear passengers then the seat belt assemblies and retractors are good for another 10lbs or so as well. I’d leave the seats in just because I like the car to “look” like its stock. Also, the glove box door has a 3lb steel plate inside it that can be easily removed. There is more places to shave lbs, so check the weight removal post for them.

  2. Unplug the knock sensor and reset the computer (pcm). This little gem adjusts the engine timing if it senses any vibrations on the motor that are similar to preignition. Now like the spare tire, this is a safety precautionary item that is there to keep you from doig bad things to your car, but just like a spare tire, it is only needed if you’re not careful. The knock sensor is there to retard ignition timing (decrease power) in the event that the motor is having pre-detonation, spark knock, or pinging. All one has to do is listen for it and if you hear excessive pinging, all you need to do is decrease the throttle until it stops, and start using a higher octane gas on the next fillup. Note: light pinging over a short duration is no big deal, nobody’s ever lost a motor over that so don’t freak if you hear it.

  3. Remove the intake resonators - Take the frame mounted air filter housing off and then unbolt and remove the milk jug sized resonator under it. While you have the filter housing off, hacksaw the opening at about where the “r” in air filter is and re-install it. As for the upper resonator, since this is “no cost”, take it off and remove the white plastic insert thats inside and re-install it. If you are willing to shed a few bucks, a visit to youur home depot or a local muffler shop will get you a straight tube that has 2 1/2" on one side and 2 5/8" on the other. I’d replace that chintzy elbow with a 2 1/2" neoprene or silicone elbow too since the stock one gets pretty small at that point too.

  4. IAT sensor relocation (1998-early 1999 only) - If you have the little guy that sits by itself in the intake tube (it has 2 wires running to it), unplug it and relocate it to in front of the radiator support so it’s measuring cool, unheated air. The ghetto versiuon will have you duct taping it as far as the stock harness wires will let you stretch it forward. A sanitary job will require a grommet and a drill bit, as well as additional wire and but connectors to lengthen the wire. At that point, I’d drill a hole in the metal cavity where the lower resonator was and have the sensor facing out toward the front bumper. nice cool air there…

more to come…

2

  1. Increasing Throttle body airflow… This little mod allows about 10% more air at full throttle. It involves removing the throttle body and removing the tps sensor, throttle plate, and shaft. Once apart, take the throttle shaft and grind/dremel off the upper “speed bump” on the shaft. The exosting screws can still be used but they will be too long, so to shorten the screws, sample screw the throttle plate to the shaft, and grind off the remaining part of the screw that is sticking out. Then unscrew them and re-assemble the throttle body. Lay the throttle plate over the remaining part of the throttle shaft and screw it down with the shorter screws, taking care to center the plate. Once in place it would be a good idea to peen the bottoms of the screws or add some blue loctite to prevent them from loosening up.

  2. Top Speed limiter cutout switch (Manual Trans Cars only). This one requires the bucks for a toggle switch so its only free if you find a toggle switch and wire laying around. This one requires you to take off the center console so you can gain access to the pcm (engine computer). On the pcm harness running along side the passenger side behind the console, you’ll need to locate the white wire with black stripe going to terminal #58 (3rd row down, 6th wire from left on pcm plug). cut this wire and splice in your toggle switch. Once finished, leave the switch in the closed position so it works normally under all driving conditions, but when you need to go faster than 106mph, when you’re up around 100mph flick the switch to open the circuit. This will keep the computer from calculating your speed and allow you to keep accelerating. When done, flick the switch back to the closed circuit and all is back to normal.

do those 6 items above and you can expect about a 15 hp increase and a 20 mph higher top speed. Not bad for free, eh?

Rob