1998 civic HX Tune up questions.

[Xhifer]

I just got some honda type 2 blue coolant. My coolant in the car is green. Not sure if it's prestone or old Honda antifreeze. I don't want to do a flush because it might not end up as 50/50, since the new blue coolant is 50/50 prediluted. Is it okay just to drain and fill, mixing the blue and green stuff?

[mswehx]

sounds like prestone,i don't think honda uses green coolant at all as long as there both made of the same mix glycol base it should be ok, pull the overflow bottle and mix a little of both and see if they mix together or not.

[Xhifer]

I got 45 MPG today almost all freeway; 230 miles at 70-80 MPH the whole way there and back, and AC on. However, my last fill up I got 33 MPG doing 80% highway and 20% city. I shifted below 2.5k RPM every shift too. Does this seem accurate? I was expecting 35-39 all city.

I feel like shifting at 3k RPM would save more gas too because it feels so underpower when I shift at 2.5k RPM.

What's the best plug gapping for best FE?

[mswehx]

shifting at 2500 is better at 3k the car is hitting the vtec cam lopes using more gas,spark plug gap(1.1mm or .043in) go bigger stress the coil: try to stay in the highest gear when in the city,hills will kill the mpg going up not so much down. good luck. Mike

[California98Civic]

Originally Posted by Xhifer

I got 45 MPG today almost all freeway; 230 miles

How are you measuring mpg? You have a gauge? You refuel? How? I would follow stock on the spark plug gap.

[Xhifer]

Originally Posted by California98Civic

How are you measuring mpg? You have a gauge? You refuel? How? I would follow stock on the spark plug gap.

The most common way? I fill up at a pump, reset trip meter, drive 230 miles, go back to the same pump, fill up, and divide 230 miles by gallons filled at the same pump.

I do not have a gauge. I've tested my trip meter and it's spot on.

So stock is .043? The manual doesn't state the gap.

[mswehx]

yes u need a gage to get it as per spec. ,I calc. my mpg after fill up i only use non-ethenol gas,ethenol doesn't get the mpg and it's corrosive,i don't know if calif. sells non ethenol. I have the honda servie manual gives all specs.

[California98Civic]

Originally Posted by Xhifer

The most common way? I fill up at a pump, reset trip meter, drive 230 miles, go back to the same pump, fill up, and divide 230 miles by gallons filled at the same pump. I do not have a gauge. I've tested my trip meter and it's spot on.

The biggest source of error with this method is the very significant differences you'll find between one pump and another even at one station. The imprecision of the pump and the car's fuel tank gauge is notorious, and it might be the reason for much of the fluctuations in your FE numbers. You can mitigate but not eliminate errors in two ways: (1) always fuel up at the same pump at the same station, filling the tank from near empty, and setting the handle to the slowest flow rate, stopping at the first click. (2) buy an after market gauge, such as the Ultra Gauge or the Scan Gauge. It best to do both of these. The on-board fuel gauge will allow you to test your mods with more precision, over more tightly controlled conditions.

As for the gap, I'm sorry that I don't know the HX recommendation. I'm surprised it's not in the Honda Service Manual or your owners manual. But another option, if Brucepick does not know, is to call a dealership or (better) the autoparts store where you bought the plugs and ask... see if they'll help.

Good luck... and hey... start a fuel log here on EM for your car. It's a solid and easy way to record your performance and examine your progress.

james

[PaleMelanesian]

Spark plug gap: 0.039 - 0.043 in. (1.0 - 1.1 mm)
1996 Honda Civic - - Search Auto Parts | Automotive News

[brucepick]

Originally Posted by PaleMelanesian

Spark plug gap: 0.039 - 0.043 in. (1.0 - 1.1 mm) ...

Yup. My Haynes says the same thing for the D16Y5 (the HX engine).
Same gap is true for the D16Y6 and D16Y7, but they take a slightly different plug.