Well i bought the car in april of this year. When i got it i had to press the gas pedel lightly when i first started it up and hold on the gas pedel for 3 mins till it gets somewhat warm i guess, then it'll drive good (well somewhat good, when it gets too hot the rpm goes to 3000 rpm idleing level). So i took it to a backyard meechanic and he messed with the idle speed, and so it starts up right way but i think it eats up gas. Now the problem is that the reason why its does all this is cause a vaccuum hose is unplugged, and has to stay unplugged cuase if i plug it back in the car would stop. or idle very very slow then stop. I cleaned the iacv senser with carb cleaner last night, didn't do nothing. Heres a video of what i'm talking about http://www.youtube.com/watch?v=dTKroVxRmsw
Thats my honda civic. Any of u handsome devils know what the hells going on?

 

Have you tried plugging your vac.hose back up, and adjusting your idle screw?

 

yeah but wouldn't that just increase the fuel consumption? its sucking alot of gas as it is. My civics getting 350 kms off of one full tank, thats really low for a civic, my friends civic gets 800 kms, well very close to that.

 

You need all the sensors hooked up for proper economy. Idling too high is annoying but it only wastes a tiny amount of gas. Vacuum leaks anywhere will cause it to idle too high.

See if your IACV is actually doing anything. Measure the resistance between the two pins. I think it's supposed to be somewhere in the tens of ohms. If it's open circuit, the valve is bad. When running at a normal idle, unplug the wires to the IACV. The engine should slow down or stall. If it doesn't change, the IACV may be faulty, or it's still dirty and stuck.

See if you can buy the whole throttle body off of a junked car and swap it as a unit. I never had to mess with mine but they look tricky to adjust. Everything should have been set up at the factory, and it is really not a good idea to tinker with the screws. Also there are a couple of vacuum diaphragms on there that could be bad. Test those by hooking a hose to it and sucking on the hose, the linkage should move and no air should flow through the hose.

Also, wrong timing (cam and/or spark timing) will kill your gas mileage. That would be the next thing to check after getting it to work with all the sensors and lines hooked up.

 

Now that you mention it, when i was changing my spark plugs back in april there was oil in two of them, ppl told me that its the old engine and don't bother with it. I swapped the old spark plugs and left it alone, would that affect miliage?

 

Oil on your plugs is a huge warning. Are you burning oil? White smoke out the back?

 

no white smoke, my oil almost never needs to be topped up, i've been driving it like that ever since i bought the car. Although my cars slow accleration,i don't know if thats cause of the iacv or the worn out engine. But the engine runs good i think, well in terms of it starts in the coldest weather and that it doesn't seize on me.

 

the oil in the spark plug tubes, means you need new spark plug tube seals, it comes with a valve cover gasket kit. and the reason you are burning alot of gas is because of that vacuum leak, also your fitv may need to be replaced, do like mk378 suggested and get another intake manifold and put it on ur motor, and hook everything back up.