My car is a '94 Honda Del Sol with a B18C1.

First problem is the unstable idle. It's been there since I bought the car almost 6 months ago. Never really bothered me but it's starting to get annoying. It'll rev from 1000 to 1500rpm once it reaches operating temperature. It'll usually die off sometime later, but sometime it'll go on forever. When first first starting up it'll rev up to about 2000rpm and drop to 1500rpm, where it'll stay until it reaches temp. I've searched this many times and this problem seems fairly common. Tonight I took off my throttle body and cleaned it good as new, then took off the IACV and cleaned it out best I could. Didn't seem to dirty to begin with. Put it all back together and the problem is still there. I fiddled with the idle needle some. Unplugged the IACV and tried to get it around 500rpm as I read in a previous post. Even with the needle all the way in, it'll only go down to 800rpm. This becomes 900rpm when I plug the IACV back in. Turning on accessories will cause a momentary drop in idle, and off a momentary rise. Is it ok to leave the needle all the way in until I find a better solution? This leads me to believe I have a vacuum leak. What's the easiest method to find a leak? I'm going to give the propane method a try unless someone has a better idea.

Second problem is some misfiring. A few days ago I decided to wash out my engine bay. I was trying to be careful not to get any water where it shouldn't go. Car ran like crap afterwards. After a couple trips it felt like it was misfiring bad. I pulled the spark plug boots to take a look at the plugs and the holes down to the plugs were about half full of water in two of the holes. I was able to get the water out by jamming some paper towels down in there and the problem seemed to go away. Tonight after working on the throttle body and IACV I noticed the problem was still there. Unplugged the boots again and one still had water in it. Could this be new? Could coolant be leaking around my head gasket? I was pretty sure I got it all out the first time and I left the boots unplugged to let any leftover water evaorate out. It was too dark to see if the liquid had any color. Did I do any damage by driving with two spark plug holes filled with water? I'm really hoping it's not possible water could leak into the engine through the plug somehow. Can anybody confirm that?

At my exhaust tip there's some water droplets. This only happens when warming up. Could my head gasket be bad? I've kind of been suspecting this for a while. I also have some black soot falling out of my exhaust that I've posted about before. It seems like it's gotten more liquidy. It doesn't really smoke until you hit VTEC. The engine has around 75k miles on it. Is a head gasket an easy job for a first timer, and about how much do they cost?

Thanks in advance to anyone willing to share some advice and experience with me.

 

EDITED

You don't need a head gasket.

Water is a byproduct of just about anything burning including gasoline, wood, natural gas, propane, etc. That's why you have water out of the tail pipe. That's not a problem. Water in the spark plug tubes could cause the wire to send the voltage through the water instead of the plug causing it to run rough. Just dry it out. Also, in the mean time, you will be running really rich and may nead to clean or change the plugs. I've also heard about water getting into your air intake when a car goes through rain or puddles. One guy said that the rough idle went away with a few days. I would at least look at the plugs.

As for the idle bouncing...I have the same problem and haven't figured it out yet. My idle screw is all the way in too. I doubt it would cause a problem unles you "tighten" it. Once a screw makes contact on the throtle or a carb., you don't want to force it any.

 

I had the same problem like you had. High idle and rough. also water's coming out of the tail pipe. there is only one thing that I did and it works. take the head out and take it to a machine shop and have it shave.I know for a fact that when you have a head blown gasket it usually mix oil with water. But remember that it's not always right. I have experience it with my crx. give it a try i know it will work. lot's of work but it will be worthed. also change your valve seal in the mean time you having it shave. good luck

 

Would just replacing the head gasket fix the problem, too, or do you mean shave the head and replace the gasket? I think I saw some bubbles in my oil last time I checked, but I'll have to go see for certain.

 

I had the same idle symptoms as you, and searched, searched, searched every forum. I'm telling you I did everything (IAVC, FITV, adjustment, timing, even replaced the O2).

Finally fixed it by filling up a squirt bottle with water, and started spraying stuff. Turned out to be the TB gasket. Then it made perfect sense. Before the engine warms up the butterfly in the TB is partially open, after the engine warms up it almost closes, and the IAVC controls how much air bypasses the butterfly, and starts controling idle. Once the butterfly closed the engine started pulling air in at the TB gasket. Then the IACV would try to compensate, over and over causing the fluctuation. I bet you have a leak either at the TB, or IM.

 

this honestly sounds like a "Fast Idle Thermo Valve" issue. I had this exact same thing about a year ago and is fairly common across all Hondas.

 

Cool I'll look into it. I thought I read somewhere that said B18C1's don't have Fast Idle Thermo Valves. Anyone know if this is true?

EDIT: This is a '98 B18c1 so it has one of the "newer" IACV's. The FITV is supposed to be incorporated into the IACV. There is a hex screw on it. Could that be an adjustment?

 

do a compression test, it doesn't sounds like a head gasket problem & the only way water got into your spark plug hole was from the top while u were washing it.. dry it out as much as possible, pull the plugs & make sure they are ok, change them for the hell of it if u want to be sure just coz they are cheep. then look into your vacume leak problem could be anything from a hose to the TB & IM gaskets as already stated by others.

just keep trouble shooting & you'll get it figured out from process of elimination.

To answer your other question. No, a head gasket job is not something i would recommend for a first timer, almost everything has to be tore down to get the head off!

best of luck to ya, keep us posted

 

Are those cheap compression test kits on eBay any good? For $20 to $30 I'd much rather buy the kit since this probably won't be the last time in my life I'll have to do the test.

I'll probably change out the plugs since they're cheap, or at least pull them out to see how they are. I'm also due for an oil change.

Guess I'll have to have a friend help with the head gasket. Might wait till next summer to do it.

Thanks for the help.

 

No need to use ebay. Just get a compression gauge from your local auto parts store. Should be about $20-40.