/diy/ - Do It Yourself

[Anonymous No.313039]

My '95 civic has some weird idling problem. Its a 5-speed and whenever stopped (or more specifically, not in gear) the engine surges between 1500 and 2000 rpm. Sometimes after driving for a bit it'll start to surge less, about 1000 1500.

I checked some boards and read about checking the PCV valve. So I did, and it was undamaged. So then, not being a mechanic and really knowing what I'm doing I found this thing (pic related) on the passenger side of the motor.

I'm not sure what it is, but it has four plugs. Two of which are corroded and falling apart on the inside, the other two look brand new being a shiny gold color.

Can /diy/ tell me if this is related to the idle problem, other things to check for the idle problem, and what the fuck this thing is and why shits corroded to hell?

>pic related
>the thing

will bump with pics I took of the plugs.

[Anonymous No.313041]

>inside of bad plug

[Anonymous No.313043]

>bad plug itself

[Anonymous No.313044]

>good plug
>attaching end is clean on inside as well

[Anonymous No.313069]

im not an expert but maybe it could be a leaking fuel injector? seal kits for injectors are pretty cheap and honestly its not that hard to do. it might be worth doing just to try and rule fuel injectors out. also check for leaks in the intake boot, past your mass air flow sensor. stretch the boot and look for any cracks.
a rise in idle rpm is kind of strange, are you getting any warning lights?

[Anonymous No.313072]

distributor bro, need either new cap or probably whole new one

[Anonymous No.313078]

You just need new wires , while you are at it change the plugs and rotor cap

[Anonymous No.313079]

>>313072
how would replacing the distributor help a high idle rpm issue? distributor would only cause the engine to not fire, it wouldnt magically make it start consuming more fuel and air.

[Anonymous No.313082]

>>313079
It would if it was faulty and off time

[Anonymous No.313098]

those are your spark plug wires. they are probably fine. if you were miss firing, you would most likely know it. its probably an air intake issue. it might be your maf sensor

[Anonymous No.313104]

>>313039

umm, you need to get (or do) a general service called a "tuneup". seriously -- cars of that vintage have electrical parts that wear out (distributor cap, spark plugs, spark plug wires, and inside the distributor, a rotor) and need replacement. If wires are corroded and loose, that's bad.

PCV needs cleaning, probably, and if the hoses to it -- and other things on the engine -- are stiff and leaking (usually vacuum, eg. negative air pressure) then the engine will run like shit for all sorts of weird little reasons.

A "tune up" generally means, replacing wear items (before they fail outright) and adjusting all the things that need tweaking.

Some of it you can do yourself with little skill but some of it will require *some* skill. It's doable, but if youve not done it before, find a friend or has or RTFM a lot.

[Anonymous No.313115]

>>313039
Could also be worn throttle shaft bearings; when they wear the engine starts sucking air through them, leaning out the mixture, and raising the idle. It'll do it less when the engine is warmed up thoroughly because metals expand, thus reducing the gap. Try squirting a little oil on the throttle shaft bearings while it's idling; if the idle goes down to normal and/or there's a little puff of smoke out the exhaust, then they're worn. If so you should be able to pull the throttle body and take it to a shop that does carburetor rebuilding, they can replace the bearings.

[Anonymous No.313116]

OP, examine your throttle butterfly valve. Had a problem very similar myself, went down the scrappers, picked up a replacement and bob's your uncle it sorted it right out.

[Anonymous No.313117]

>>313115

maybe so. but solving known or very-likely problems first, before further diagnosis, is required. "motorboating" (revs rising and falling) on a non-closed-loop car (95 honda will be carburetted, not EFI I think) does usually mean air leaks'n'shit, as you say. but more basic troubles (fallen-off or cracked hoses, clogged air filters, badly dirty plugs, timing off, etc) make things confusing.

Idle adjustment can compensate for *some* throttle shaft wear, but at some point, as you point out, it'll need replacement.

[Anonymous No.313138]

Everyone stand back, I've got this.

It's most likely your "fast idle thermo valve" and this is why:

Corroded spark plugs will not cause the car to idle higher and are most likely not related to the high idle problem but they are an issue and will need replacing FIRST.

So step one, replace your spark plugs and wires. This is cheap and needs doing.


Now on to how a Civic's engine idles. There are two main devices on the engine that control idle: the idle air control valve and the fast idle thermo valve.

The idle air control valve makes the engine idle a bit higher when you first start it. This allows the engine to warm up faster (especially good for cars in colder/icy climates.) After a few minutes of running the engine is warmed up (the coolant gets hot) and this device "shuts off" and the fast idle thermo valve takes over.

The fast idle thermo valve is actually what controls the idle the rest of the time the civic engine is running. It is most likely the problem and will need replacing. Here's why: You said that after driving the car for a while (after it is warmed up) you continue to have idle problems. Having continuous idle problems after the car is warmed up is a sure sign the fast idle thermo valve needs replacing. This is common in older Hondas, so

Step 2, after replacing your spark plugs and spark plug wires, REPLACE THE FAST IDLE THERMO VALVE.


I have to get back to work and you're welcome

source: been there, done that

[Anonymous No.313139]

Side note, corrosion doesn't mean "no spark." a batter can have corrosion but it will still start your car.

If corrosion was related to the idle problem your car would bogg down, not idle higher.

[Anonymous No.313206]

>>313138
This guy seems to know his shit, start there OP.

[Anonymous No.313435]

It's the vtec trying to kick in

[Anonymous No.313448]

>>313435
Yo

[Anonymous No.313458]

>>313117
cars past the 90s were all EFI....
and a 95 civic is definatly not carbed.

OP most of the time when an engine is idling high its due to vacuum leaks, throttle shaft wear as a few posters have mentioned can cause this, as well as a host of other things.

also replace that cap and dem wires, could also cause a higher idle issue and all sorts of other problems.

[Anonymous No.313489]

>>313039
>>>/o/

Friendly suggestion, you'll get more help there.

[Anonymous No.313492]

>>313489
>>313458
im from /o/. he probably won't honestly.

he'll get more knowledge, but not much effort to try to solve his problem

[Anonymous No.313655]

A friend of mine drove an efi nissan sunny that the power used to surge up and down when driving. He replaced the fuel pump and swore that that fixed it. I doubt it would but I mentioned it in case you were interested.

[Anonymous No.313675]

>>313138
In following with what this man said, it's a good idea to check your coolant levels as well. IAC valves make their decision to modify idle based on coolant temperature, and if your coolant is severely low, or there's air bubbles in the system, you'll get a screwy idle.

[Anonymous No.313952]

>>313138
EDIT TO THIS POST:

Holy crap I just realized I typed it all backward! The fast idle thermo valve controls the idle first, then the idle air control valve takes over.

In short, REPLACE THE IDLE AIR CONTROL VALVE, NOT THE FAST IDLE THERMO VALVE.

Sorry for any confusion.

[Anonymous No.313953]

Replacing spark plugs and ignition wires is always a good move for maintenance, OP. A cheap one too, that has quite a bit of an effect.

[Anonymous No.313984]

>>313039
If this is still being monitored, don't listen to these people. Your distributor cap and plugs do need to be changed, but your problem sounds like the vacuum.

>same problem, but I'm also a mechanic

[Anonymous No.314013]

clean the throttle body and egr passages, check for loose vacuum lines or intake leaks.

[Anonymous No.314031]

>>313079
borrow or get a timing light..
youtube how to use it
adjust the timing from the distributor
also replace rusty wires while you're at it
protip: remember what position the spark cables are plugged because fire order matters.

[Anonymous No.314032]

>>313984
this guy

[Anonymous No.314036]

>95 civic
>obviously not cared for

op, PLEASE go ask your dad or grandpa or someone who can help you on your car to replace your timing belt
They fail on those hondas, and will destroy engine to where its not viable to fix it

15$ belt and an hour of time will help you out tremendously

[Anonymous No.314042]

>>314032
Call me Randy.
But for real, vacuum, look it up.

[Anonymous No.314049]

>>313458

So the carburetor I just rebuilt for my 94 B2200 is all in my imagination?
GTFO you fucking dipshit.

>OP
Lots of good info here. Doing the simple stuff now (cap & rotor) will save you lots of money and heartache.

[Anonymous No.314059]

idle control valve. i had that same problem on my 95 coupe

[Anonymous No.314085]

great to see someone else is also duct taping their mid-90's civic together

[anonanon No.314323]

>>314049
Im gonna guess there was a LOT of freaking vaccum lines on that bowl of spaghetti-looking carb. Amiright? I had a 92 tercel with a carb and that thing drove me crazy. I finally just scrapped it bc I got tired of figuring out the vaccum.