Hi- I was driving on the expressway and when i got off the exit ramp my car started shaking around 30mph down to idle. It idles extremely rough at idle in park and drive and shakes to about 30mph every time. I had oil on my plugs so i replaced them as well as the valve cover gasket, threw in a new air filter also, what could cause this? Please help asap, i need the car to commute to school

90 civic lx
1.5

Thanks

 

new spark plugs might help out the roughness. dunno what else it could be..

 

I changed the plugs when i changed the gasket and it's still idling terrible and the first 30 mph are extremely rough

 

cap n rotor?

 

first thing i would do is get some well insolated plyers so you dont get shoked then with the engine running pull one plug wier of at a time if the car runs the same with one of them unpluger then you know its a problem related to that cylinder. if it runs the same with the plug wier off if you dont have a spark tester use a philips head screwdriver put it in the wier then holding the plastic handel have someone turne the engine over put the metal part of the screw driver close to a bolt to ground it if it dosent spark you know the problem is befor that in the ignition system. if it dose spark it is some thing else. i dont want to alarm you but oil on the plugs normaly is not a good thing, after doing the above i would also pull your plugs agin and see if there is more oil on them if there is i would go to an automotive store and ither buy or rent a compresion check tool its a verry simple little tool you screw one side in to the spark plug hole and on the other end is a meter that will read the compression do that to each cylinder and if it comes to that post the results i dont want to scare you but it could be a blown head gasket, another way to check if it is a head gasket is check your oil if it looks milky then it is a head gasket if it dosent it still might be but not 100% the head gasket can blow in multiple directions so you wont always get water in the oil and you wont always see smoke. one more thing if you have low compresion it also could be the piston rings witch if it is you will have to replace the head gasket anyway.
Sorry this was so long but i hope it helps

 

pcv valve can cause rough idle and poor acceleration. if yer lucky and its only that u can buy a new one for like 4 bucks. but i mean a lot of things can cause that. simple things like a broken vacuum line. or bad injectors. cap and rotor. lots of things.

if u can get your hands on a throttle body, wouldn't hurt to change that. i've got a 91 dx an i've fixed many idle problems by just changing the throttle body.

 

HI-Thanks for all your input but I have some new info that might help. When my car is running and i pull the sparkplug wire on the first plug the car does nothing. If i pull plug wire 2, 3, or 4 the car's idle drops a condiserable amount. I replaced the valve cover and there is still oil on first plug. Could i have damaged a gromit or rubber seal. Some one said this might be my head gasket but i don't think that could cause oil on the plugs.

Thanks

 

dead cylinder? u mite have blown a piston. i've had it happen but u'd know it cuz she'd smoke like a bastard. maybe that plug just isn't firing. did u change the wires when u changed the plugs? that one wire mite be fubar'd.

it wouldn't hurt to do a compression test and post the results. that will tell you a lot. if yer compression is extremely low on that cylinder then you mite have a blown piston, head gasket or burnt/stuck open valves. when u open hte oil cap is there a lot of blowby (smoke pouring out the hole) if there is, then combustion gases are getting past the combustion chamber. either bad rings or a blown piston.

is yer car burning any oil? if not then its probably just a problem with that plug not firing. i'd say this would be your best case scenario.

 

since you know what cylender it is see if that one is fiering if you dont have a spark test do the screwdriver trick see if you are geting any spark if your not befor you buy new wiers move one of the other wires over and see if it sparks if it dosent then you got it down to cap and rotor if it sparks then you know its the wier. you should also do a compresion check on all cylenders if its a piston not sealing then you will only have low compresion on that one cylinder if its a blown head gasket cylinder 1 will probably have the lowest then it will progresively go up like cylinder (1) might have 50lbs (2) 90lbs (3) 120lbs (4) 150lbs ore some thing along those lines. geting it narowed down try those and yes post the compresion check it will tell you alot but do it on all 4 not just one get as much info as possible.
hope this helps

 

P.S. blown head gasket can cuase oil on the botome of the plug and so can bad piston rings, if it was the gromets by the plug holes you would have oil on the top of the plug and in the plug hole.