Honda Civic Forum - DIY: Forgotten Tune Up Mods

In my ongoing quest to keep this car running like new, i thought i would post some of the recent mods i did. In addition to these, you should keep your battery and terminals in good condition and inspect ground wires for corrosion. Make sure to check the electrolyte in the battery every month and add distilled water if needed. most battery have caps that can be pried open to add water. make sure terminal clamps are tight, and wires are securely attached. Anything connected to the + battery must have a fuse to prevent car fire if the wire shorts out. here is a list of fuses and wire sizes. its a bit on the safe side, and usually you can get away with using a fuse thats several amps higher for each wire gauge.

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1. primary oxygen sensor. these are supposedly rated to last 100k miles by honda. I found that after 20k miles, the performance starts to drop noticably. I just switched mine out at 80k miles when the check engine light came on for low response. I suggest not waiting that long. The sensor is only $50 (01-03 civics) from advance auto and should be replaced between 20-40k miles, imo. it is super easy to change. you just unplug the connector, push out the wire grommets from the stock metal clamps, and unscrew the sensor. jacking up the front driver side of the car made things very easy. i used a cresent wrench and hollow pipe breaker bar to get the old one off, no special tools needed. they do have a special deep socket with cutouts for wires to fit if you want to buy another extra tool lol.

here is a pic showing the old sensor screwed in the downpipe just below header (EX) or in the manifold (LX).

for the EX, it is much easier to get to from under the car.

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you want to get the BOSCH sensor OEM type with connector for 01-03 civics (part 13532), which is exactly the same as the stock part. 04-05 civics use a very expensive wideband sensor with a different part number. It even says NTK on the outside. Be VERY careful when installing the new one. the sensor is extremely sensitive. Do not touch or drop the tip. Keep the inside AND outside of the sensor free of dirt and liquids. The tip gets old just by being exposed to exhaust gas, but the outside can be damaged too by fluids like antifreeze. always keep it clean and wipe off any road spray with a damp water cloth. Apply a small amount of anti-seize grease to the threads before installing. Be careful not to get any on the sensor! be careful when handling a new sensor because alot of them already have anti-seize on the threads, which can easily get all over the sensor when opening the package.

You will notice immediate increase in throttle response and decrease in idle surge when coasting. The auto trans will shift from R to D faster. and you will get 2-3mpg better gas mileage compared to an old sensor.

UPDATE!! There have been problems with Bosch putting the wrong sensor in the box. I have heard of reports where user bought a primary sensor but instead there was a secondary sensor in the primary box. looks like someone messed up at the factory. So if you can, try to buy the sensor at a local store so you can examine it. here is a pic of the two types of sensor. on the right is the primary, and on the left (with a plastic cover) is the secondary. If you install a secondary into the primary spot, you will have problems since they are totally different sensors. beware of what you are buying and be sure it is the correct part in the box. These part numbers are for the 01-03 civic EX but again you must open the box and be sure the correct sensor is inside.

primary (upstream) downpipe sensor: bosch 13532

secondary (downstream) in the cat converter: bosch 13534

primary on right, secondary on left! do not go solely by the part numbers.

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2. EGR valve. this thing came stock on all civic EX 01-05 and all 04-05 civics. Its purpose is to recirculate exhaust gas back to the engine in order to reduce harmful NOx emissions and also make the engine run slightly cooler. You can remove it with a socket wrench and extension bar, then spray inside the bottom with carb cleaner. spray until you dont see any more brown/black fluid coming out. Let it dry and then reinstall. Also a great time to paint the lower rusted portion of the valve before reinstalling. You can use a new gasket, but the old one looked fine so i didnt bother.

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the car may take a bit longer to start up the first time after this mod, since it needs to adjust to the new conditions.

3. VTEC solenoid. Located on the rear of the engine, it controls when the cam profile switches under full throttle (racing). It has oil passages and also a screen mesh filter than should be cleaned regularly for optimum flow. A clogged solenoid screen (usually from using a K&N air filter that lets in too much dirt), will cause the check engine light to come on if enough oil is blocked. Engine code P1259 vtec malfunction. There are only 3 bolts holding the solenoid to the engine head. they are shown partially removed below.

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there are three other top facing bolts that hold the head on. Should be very easy to remove if you have aftermarket intake. otherwise, you will need to disassemble the stock intake and hardware.

inside of solenoid with filter screen. remove the gasket and clean the screen with a cotton cloth. also clean around the mating surfaces and remove excess dirt on the edges.

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you can take off the head and clean around that too. make sure the solenoid button works properly by pressing on it a few times.

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4. PCV valve. located to the right of the throttle body down in the middle of the bay, it allows crankcase gases to vent and then recirculate with fresh air in the intake manifold. over time the stock valve may become clogged with oil deposits. Since the valve is entirely metal, you can spray it down with carb cleaner, then reinstall it. it is a simple spring loaded valve and should not need to be replaced, ever. be sure not to lose the washer when removing. First pull off the rubber hose connected to the valve, then use a 17mm deep socket to remove.

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5. EVAP canister air filter. Bet you didnt know the car had four air filters. (one in the engine bay, two cabin filters, and the evap filter). This one is hiding out in the rear of the car, next to the fuel tank. It has one bolt holding it to the frame, and two hoses that just pull off. be sure to install the new one in the same direction. It is $20 from dealer and i recommend changing it every 100k miles. It was dirty, but not that bad. The filter is part of the vapor recovery system our cars have to burn fuel vapors that are trapped in the evap canister. it draws in fresh air from outside. here it is on the rear drivers side

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taken off the car

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and cut open just for fun lol

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6. throttle body and IAC valve cleaning. over time, the throttle body and idle air sensors will get clogged with carbon blow-by and eventually get stuck, causing noticable idle issues such as stalling and surging. usually the worst deposits occur when the motor is breaking in during the first 20k miles. after you clean it once, it should not need cleaning for a long time (i cleaned mine 4 yrs ago and its still spotless inside).

first remove the factory airbox or aftermarket intake. the throttle body is underneath. locate the basic parts. IAC valve is bolted to the throttle body and has two coolant hoses running into it. remove the radiator cap to depressurize the cooling system (only remove cap when car is cold after sitting overnight, and wrap a towel around to catch any coolant spray). remove the vacuum hoses, sensor connectors, coolant hoses, and throttle cables (they unhook when you completely open the throttle and slide out the locking pins). then unbolt the throttle body. you may want new gaskets for the TB/IM and TB/IAC, but i reused the old ones.

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the IAC has three philips screws holding it. be sure to use the exact size screwdriver to remove them. they are very tight and easy to strip. use some penetrating spray to loosen them first. IAC is removed and clean. you want to spray carb cleaner all over inside the port. try to avoid getting the connector part wet. it should look spotless when youre done. keep going until the carb cleaner flows out clean. use q-tips if you have to scrape.

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throttle body is not as important, but you should clean inside anyway and spray carb cleaner on the middle valve. i polished mine up, but ofcourse it looks nothing like that now.

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once youre done cleaning, reassemble everything. whenever the throttle body is removed, you must complete the idle learn procedure otherwise the car will not idle properly. to do this, start the car and warm it to operating temp. you can drive around to do this and should not have too many problems except unsteady idle. park the car and turn it off. open the hood, locate fuse box, and remove the FI ECU fuse.

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put the fuse back in, close hood, and start the car. let it idle for 10 minutes in park or neutral without using any lights/accessories or pressing the gas. after 10 mins, shut the car off. start it again and go for a drive like you normally would. it will take up to a full tank of gas for the ecu to relearn fuel maps and readiness codes. the idle will be set, but it may take a while until the ecu adjusts and you start getting good mileage again. do not perform these mods if you are having the car smog-checked immediately afterwards. it is a guaranteed fail. you need to wait at least 100 miles or more.

thats all for now...keep your car running its best!