Hard to find vacuum leak???

First of all, I am new to this forum and am really hoping I can figure out what is up with my car here. I have been ignored on other forums posting the same issue :bs:

I have owned this car for three years. It has been a VERY good car. Yet I cannot seem to find out what is wrong with it. And it's been getting WORSE!

As of now, I currently have fluxuating idles. When up to operating temp, they are moving between 850 and 1100 in neutral. You can definately hear it. It does it in gear too. This is the new addition to the current issues. I have a horrible MPG (below 20), a slight misfire (you can feel it at idle) and it can be heard from the tailpipe. Sort of a studder every few seconds. It also idles and drives rough. I can be heard pulling into the driveway from INSIDE the house and I don't have and mods to my exhaust and I have no leaks. The keys rattle violently in the ignition when I accelerate and it's been annoying to deal with for three years. It's annoying to passengers too. The car is also quite weak and has no get up and go. Punch the pedal and it boggs down before it responds. All this has lead me to a vacuum leak. Squirting a can of carb cleaner over everything (vacuum lines, vacuum advance, seals, etc) and I have not found anything yet. I am lost and I am about to get rid of the car because now it's running horribly and barely passes emissions with a very high NO2 at idle.

P.S. I am not sure if this is relavent, but I figured just in case... when the engine is almost up to operating temp, clicking can be heard from a set of relays bolted to the passenger side panel in the engine bay. The clicking lasts for about ten mins until it's all the way warmed up. After the clicking goes away the idle still goes up and down, which is new. The idle seems to change with the clicking and the engine runs smoother and rougher as they click rapidly. (the car has also always done this, not sure if it's normal.) Are the relays failing? How do I check them? What are they there for? The genuine Honda manual I have serves no answer to the purpose or testing of these... they have vacuum lines attatched and have electrical connectors fitted to them.

Here's things I have done in an attempt to fix it in the past three years.

Changed coolant
Changed spark plugs+Wires
Changed distributor rotor+cap
Changed various vacuum lines that were old and weren't sealing
Carburetor rebuild
Checked all electrical systems

Sorry for such a long post. I hope someone can help. I really want to see what the full potential of this car is, even bringing the MPG up. Thanks!

sounds like seperate issues. i would bleed the coolant system or even check to see if your coolant is full. thats usually what causes flucuating idle. the rough idle could be alot of things from motor mounts to ignition system. check your plugs for the misfire if theyre fouled thats an easy fix... that bogging could also be your timing being off... i had the same bogging problem and i adjusted my distributor timing and it fixed the bogging and improved my bottom end so give that a try.

I thought I had a vacuum leak, had lots of your symptoms, and did all the usual tests with no luck. Turns out my timing belt was 1 tooth off. It's easy for a mechanic to screw up because you're supposed to set the cam straight up in relation to the engine, but sometimes a mechanic will missunderstand and set the gear straight up in relation to the ground.

There are several vacuum actuators that mess with the idle speed.

In the passengers side we have the Automatic Idle Speed Control and the Choke assembly.

In the drivers side we have the AC Idle boost control.

When the idle is fluctuating you can see the throttle moving open and close, but all the valves move at the same time so you don't know which one moves first.

So you need to back off the adjustment screw of the Automatic Idle Speed first and check if your Idle speed stabilizes. If so, all your problem is reduced to the hose that controls such actuator.

If not, put the screw back to its original position and check the next actuator and so on.

For your low MPG and other driving problems, its obviously caused for a excess of fuel poured into the engine. It can be the float not sealing, a loose ventury, a missasembled carb, etc. You need to test each component at the time.

Download the manual from the forum and wish you good luck! It isn't that hard as it looks.

Buy borrow or rent a vacuum gauge. It can tell you a lot. There are some threads in the Carb section that tell you how to hook it up. Post back when you have some results and you will be sure to get help.

Thanks for joining the site.

Definitely sounds like a really bad vacuum leak. Did you, by any chance, spray carb cleaner on the carb base gaskets and intake gasket? Those would be the places I would look for such a big leak. As bad as it is, you should be able to hear it whistling at you. Just stick your head in the bay and start moving around.

Thanks everyone so much for your replies. This is a very helpful community. I'll look forward to doing all the things you guys said to check when I get the time. Probably sometime during the week. It's winter and when I get off work it's dark. Without a garage it's sorta difficult. But I'll get around to it this week for sure. The sooner I fix this mess, the better. Before it's bad enough to not stay running.

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Originally Posted by Dr_Snooz

Definitely sounds like a really bad vacuum leak. Did you, by any chance, spray carb cleaner on the carb base gaskets and intake gasket? Those would be the places I would look for such a big leak. As bad as it is, you should be able to hear it whistling at you. Just stick your head in the bay and start moving around.

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Yes, I checked them about 6 months ago with no luck. I sprayed around the head, intake, exhaust, carburetor base, and valve cover gaskets, and all hoses/lines. I even went around the spark plug holes. No luck. Should check again. I've thought about going in there with a stethoscope, removing the chest peice, and poking around in there. I just need to get my hands on one of those... I am sorta intimidated by the box on the passenger side that has the 12 lines going into it... I don't even know where to begin on testing what's in there.

I thought I would make a list of all the currently broken things on here, just in case they're related.

Alternator has intermittent regulator failure. When warm, the light comes on. It stops feeding power to the choke heater that keeps the choke off when it stops regulating correctly, so I wired a switch to the system. I stuck a deep cycle battery in there to be safe, and the system still charges when the light comes on. Weird, right? I had the stupid thing replaced 2 years ago. RE-Built from Kragun. Bad idea...

Power steering rack and pinion, pump, and lines are leaking/shot. Need a whole new power steering system. When I put oil in the reservoir, it comes right back out after a week or two. And it DOESN'T work when it's cold out. Pump also makes grinding noises when cold. Power steering fluid has been sprayed all over the underside of the hood.

All the bellows (boots) that hold grease and keep dirt out are broken on the wheel hubs, rack, joints, etc. and need replaced.

I am slowly losing R-12 refrigerant somewhere. I need to get it converted over and fix the leak.

My air control diaphragm (sits on the entrance to the air cleaner connected to ported vacuum that uses warm air from the exhaust manifold to warm up better in the cold) is shot. I plugged off the vacuum line to close off a vacuum leak.

I decided to suck on the vacuum lines going into the fast idle to test it one day. It has a small hole, but it's ported and is only an issue when it's warming up.

I belive that my vacuum advance diaphragm has issues with correcting the timing. The problem doesn't get better when I move it around anyway. The thing is almost $90 bucks to replace!

Are any of these issues related by chance?

*After this list of somewhat small issues, I still find it a good idea to keep the car. What can I say. Gotta love a Honda!*

Do take a look at the factory manual. There is in-depth information about that box on the pass. side, relays, etc. It's sure to help.