Not getting impressive fuel economy with the Civic

[Raccoonjoe]

wet test/leak down test.....they are the same thing. Small amount of oil in the cylinder, then compression test. However, if you've got crappy compression in the first place, a wet test usually will show crappy compression again in that cylinder.

With one cylinder being low like that, it's time to start looking in other directions. Does your oil have a gas/oil smell?? Do you have a frothy/chocolate milk substance on the bottom of your fill cap (or on your rad. cap)?? Are you losing coolant at all?? Smoke from the exhaust?

^^^ Trying to help you diagnose a little further before you decide to tear apart the motor for valves/head gasket/piston rings....

[Gary Palmer]

With the compression numbers you've got, one way or another, you have a imbalance and a problem with the number 4 cylinder. If you squirt some oil into the #4 cylinder and retest the compression, it may show you whether the problem is in the valves, head gasket, or rings. It also may not, since if you have a bad valve it isn't going to seal, no matter what you do.

Have you had any problem or problems with overheating, running low on water/antifreeze?

Their are several possibilities. First, the head gasket could be shot. This is where Raccoonjoe is asking about the oil, radiator cap and exhaust. It may be something you had happen, or it could be something which happened 50,000 miles back and it's just showing up now. If it's the head gasket, you may be able to just get away with pulling the head, cleaning everything up and putting it all back together.

But, it's a gamble. If the head is flat and the block is flat, then the gamble might pay off.

Alternatively, it might be a burned valve, in which case you would need to get a valve job and a head milling to square it all up.

If it's rings, then you might be able to get away with putting in new rings, or you may need to either get a replacement engine, or have the engine rebuilt.

What does the spark plug from #4 look like? Is it more white and clean, like the other three plugs, or is it more black, oily, sludgy looking. If it's clean, then it's probably a valve or head gasket issue. If it's dirty, then it's probably rings and a rebuild.

If you do the head gasket, I would suggest you use a head gasket for a 92 Civic Si. The head gasket is all metal, instead of a fiber compound, so it reduces the liklihood of doing a replacement later on. If you do, you will still need to get a head set, to get all of the other gaskets which are correct for your car.

[DUBPL8]

Originally Posted by Gary Palmer

Have you had any problem or problems with overheating, running low on water/antifreeze?

None since I have owned the car.

Their are several possibilities. First, the head gasket could be shot. This is where Raccoonjoe is asking about the oil, radiator cap and exhaust. It may be something you had happen, or it could be something which happened 50,000 miles back and it's just showing up now. If it's the head gasket, you may be able to just get away with pulling the head, cleaning everything up and putting it all back together.

The oil doesn't have a gas smell as far as I know, and the coolant does not show to be milky one bit.

No smoke coming from the exhaust.

What does the spark plug from #4 look like? Is it more white and clean, like the other three plugs, or is it more black, oily, sludgy looking. If it's clean, then it's probably a valve or head gasket issue. If it's dirty, then it's probably rings and a rebuild.

It was white and clean, showing normal wear.

[thisisntjared]

maybe it just needs a good old dose of sea foam?

[Gary Palmer]

Well, I don't know what to think. Is their any possibility that the timing belt might have been replaced, off by one tooth. The car would still run, but it probably wouldn't seem to much get up and go, on the highway. I know it was done by a reputable shop, but I also know a reputable shop did the belt on the wagon I'm currently driving and somebody choked because they marked the pully on the crankshaft incorrectly. I had to find TDC on cylinder 1, by pulling the plug, putting it close and then sticking a piece of welding rod in the hole where the spark plug goes. Then I could turn over the crank and find TDC and it was definitively marked wrong by the mechanic who had replaced the belt.

You can check it without pulling the timing cover, by doing the same thing I did. Use a 17mm socket to turn the crankshaft over, to where it's near TDC on number 1 cylinder. You can pull the cover to the distributor and look at the rotor, if you wish. Pull the 1 spark plug, use a long piece of wire to put into the hole, then you can turn the crankshaft to where the wire is as high as it will go and the crankshaft will be at TDC. The spark plug rotor should be at the number 1 position. If it's off by about 1/4 inch, then the belt is off by a tooth.

I wouldn't do a head gasket replacement if you don't have to and if number 4 spark plug is like you described, it doesn't sound like the rings are bad.

Does it idle a little rough?

[DUBPL8]

Originally Posted by thisisntjared

maybe it just needs a good old dose of sea foam?

I'll give that a shot after the new cat was put in place.

Does it idle a little rough?

Not at all. It idles very smoothly and stays stable.

[MakDiesel]

I dunno if this has been addressed but have you switched gas stations lately? Different blends and the occasional crap tank can screw up mileage. Without engine problems the next place to look is alignment like suggested, specifically toe, which if is out of spec can eat tires as well. Just a thought. Mak

[GasSavers_TomO]

Hanging calipers (common problem in the fronts on the Hondas) can greatly impact the MPG numbers....might check those as well.

Originally Posted by Danial

160psi on 1, 155psi on 2, 155psi on 3, and 135psi on 4

Got my compression test results in.

How was the test performed??? Those numbers are really low. I recently did a compression check on my VX motor with over 330K miles on it and got 200, 195, 198, 201 in cylinders 1-4 respectively.

[DUBPL8]

Originally Posted by TomO

How was the test performed??? Those numbers are really low. I recently did a compression check on my VX motor with over 330K miles on it and got 200, 195, 198, 201 in cylinders 1-4 respectively.

The test was performed with a regular compression gauge but we did not disconnect the injectors so my guess is that it did not give the readings correctly.

Also, I noticed that my car has crap fuel economy with the A/C on at 230-260 miles on a normal fuel tank. It's ridiculous and it also does not drive well either. This occurred after I got the A/C recharged with R12.

I don't even know what to do anymore. Anyone in the Dallas/Fort Worth area want to lend their help to me? I can't figure out what the hell is wrong with this car.

[bfg9000d]

I dont know if this has been mention but have you check the codes on the car. This might reveal something.