Installed new carb insulator= slightly higher idle?
 

I put a new carburetor insulator, & talked myself out of having my carburetor rebuilt as i get 40mpg with this car.

So I used carb spray to clean, and checked all the vacuum ports & functioned checked the vacuum controls with a hand pump.
I got the car back together and I'm 99% sure the vacuum hoses are correct.
But the idle is a bit higher than when I started ~900 going by my factory tac.
The thing that I notice it how much the idle varies when the fan kicks on.

I think I'll use some propane to check for vacuum leaks just in case I missed something or split one.

I'd like an opinion if you think this could be a normal condition after fixing my leaking carburetor insulator?
My thought is the previous owners mechanic could have adjusted the idle to compensate for the vac. leak before I got it.
Anyone experience this before?
s/t

Re: Installed new carb insulator= slightly higher idle?
 

I'm thinking the carb was adjusted to compensate for the vacuum leak. Readjust your idle speed.

Re: Installed new carb insulator= slightly higher idle?
 

It is very common for people to try to increase the idle speed to make up for an intermittent miss that allows the car to stall under certain conditions.

Was the rubber carb insulator cracked when you removed it? If so, you probably did have a vacuum leak and were running a little bit lean.

I would just lower the idle speed by turning the adjusting screw.

Re: Installed new carb insulator= slightly higher idle?
 

I third the advice so far. I've seen many instances of a PO or mechanic (especially family mechanics) adjusting things to compensate for a problem (even in brakes, alignment, tires which can be really scary)

Re: Installed new carb insulator= slightly higher idle?
 

The insulator had fairly large cracks on the sides. I could see any evidence of them reaching into the intake area though. The seal was hard and I suspected it was leaking there instead.

Re: Installed new carb insulator= slightly higher idle?
 

Update. I turned the idle down and got it to the 750rpm (factory tac), and drove it to make sure she was going to stay there all was good.
Then drove down to the emissions place ~12 miles freeway + 5 miles city. She
she acted pretty good holding the 750 rpm (would slightly hunt a few rpm, with the occasional 50rpm when the fan kicked in or out).
When I pulled in the emissions place she was idling 1100~1200 rpm! I couldn't believe it.
The guy ask how it's going I said not well. The car never idled down so I backed it out and ended up turning the idle screw way out.
Sat there and it still would creep up to ~1000.

So something else is causing this.
I'm going to the dealer and get a new O2 sensor just to check it off the suspect list. Unless someone can recommend an after market one that fits.
The Bosh unit had the wrong connector.

Things I've check already.
Vacuum leaks using carb cleaner nothing noted. I'm going to remove the air cleaner and try a better job just to double check.

I have a broken sensor on the intakes air horn Not sure what it does could this be the cause of my problem?
I resides on the under side of the air horn, just behind the vacuum pot.
The two wires look intact but the rubber is torn up an it flops around in the hole.

Re: Installed new carb insulator= slightly higher idle?
 

What kind of vehicle is this that you have a carburetor and an O2 sensor?

Re: Installed new carb insulator= slightly higher idle?
 

It's a 1987 honda civic with the D15A2 engine.
Now If I can only find the ECU and find the codes.
I under stand they are lights on the ECU, but hadn't found anything definite for the 87 models. :confused:

Re: Installed new carb insulator= slightly higher idle?
 

I've tried to insert a signature with vehicle, but can find the option?

Re: Installed new carb insulator= slightly higher idle?
 

The 87 carbed civic (I drive one) has a primitive electronic control box that uses solenoids to control vacuum bleeds according to engine temp, speed, oxygen sensor values etc. There are no trouble codes that can be accessed or that are even stored by the electronic control box.

The best you can do is monitor the oxygen sensor output with a digital voltmeter and see if it averages out to 400-500 milivolts (it normally jumps around above and below these values as the air bleeds try to lean it out when it gets too rich).

You can get a universal 1 wire oxygen sensor for it at many auto parts stores and splice it into the factory wire using the materials included with the sensor (heat shrink tubing is included with the sensor)- So you just cut the wire/connector off the old sensor and add it to the new one.

The fuel injected civics/crx's of the 1984-1987 generation do have a computer that stores codes that can be retrieved.

If you have air conditioning, there is a vacuum operated idle up mechanism that bumps you up to a fast idle when the AC compressor kicks on. It is on the drivers side of the carb, toward the back. It may be bumping up your idle.

As you have noticed, there are 50+ vacuum hoses- if any of them has an intermittent leak, it can cause problems like you are describing.

Also check the fuel level in the carb- if the float level is changing because of a bad float valve, the idle speed will change too. You can check the fuel level by looking through the sight glass on the drivers side of the carb while the engine is running.

Re: Installed new carb insulator= slightly higher idle?
 

The sensor on the air cleaner just tells the primitive control box whether the air coming through the air intake is above or below a certain temp. It is a switch that is either closed or open- it doesn't have variable resistance like the newer cars.

It is very common for the rubber to fail and for it to flop around loosely in the hole. I sealed mine in with some silicone caulk, but I doubt that it is the source of your idle problem.

Also check your choke butterfly to see that it is opening fully as the engine warms up.

Re: Installed new carb insulator= slightly higher idle?
 

Thanks Erik, I knew about you having a civic like mine. During all my searches I read lots of post from you (and others) here and knew this was going to be my forum for the Honda.

I'll check the float tomorrow. AFA the o2, do you have any brand recommendations/ PN#'s?

I'm thinking of removing the air cleaner and using a dryer vent pipe or pvc to make a stack to allow me to spray carb cleaner or propane all around the carb. I'm thinking I'll move hoses around during this process to find any faulty hoses. This isn't quite possible with the air cleaner on. What to you think of this idea?

Re: Installed new carb insulator= slightly higher idle?
 

Should I bother ordering another one?
Yes, the choke works awesome and does fully open.

How do I add a sig line?

Re: Installed new carb insulator= slightly higher idle?
 

No- there is no need to get a new air cleaner temp sensor- I don't think that is the problem.

Re: Installed new carb insulator= slightly higher idle?
 

I think that bosch makes a universal o2 sensor- just go to the autozone or advance auto website and do a part search.

You could just remove the air cleaner and temporarily plug the hoses going to it or buy extra vacuum tubing and extend them so that they can remain attached when the air cleaner is removed. The hoses that attach to the air cleaner just attach to temp sensing vacuum valves so it is no big deal if you plug them.

You can view the 87 civic factory service manual (including the emission controls section) at redpepperracing.com

Re: Installed new carb insulator= slightly higher idle?
 

My concern was the spray getting into the carb and thinking there was a vacuum leak. That's the only reason for the dryer vent, just to raise it high enough to prevent that during my testing.

One thought though. The electric solenoid on the back of the carb. Could this be the problem, and how do I check it?

Re: Installed new carb insulator= slightly higher idle?
 

Thanks for the link, it's now booked marked!

Re: Installed new carb insulator= slightly higher idle?
 

That solenoid is the anti-dieseling solenoid. It cuts off the flow of gas through the idle circuit of the carb when the key is turned off.

If your car would not idle at all, but would run ok above 1700 rpms, I would suspect that solenoid- but I don't think that is your problem.

Re: Installed new carb insulator= slightly higher idle?
 

If you're trying to put one of these in:
https://www.gassavers.org/gaslog/sig.php?id=1399
...then you'll need to add your car to the Garage by clicking on "Garage" at the top of the screen, and then click "Add Garage Entry". Next you'll need to enter some data in the gaslog. In your car's Garage page there will be a link you can paste into your sig.

If you just don't know how to put in a sig, go to the UserCP link on the same tab line as Garage. From there, click "Edit Signature".

Re: Installed new carb insulator= slightly higher idle?
 

I know what the problem is... Signatures are not available until you reach Junior Member. Once you have been a member for 30 days, and have a post count over 25 it will be available in your control panel. You also need to add your vehicles to your garage tab, and enter some fillups.

Once you have your vehicles in your garage, I may be able to manually add your vehicle's tag to a signature from the admin control panel.

Re: Installed new carb insulator= slightly higher idle?
 

When I suspect a vacuum leak on a carb'd car w/ automatic transmission, I look to see how much the RPMs drop when I put the car in gear.

For instance, my Buick used to idle at 900 in park/neutral, then 750 in gear. That's a 150RPM drop.

When I have a vacuum leak, that changes by more like 300 RPM.

By the way your engine speed is oscillating, however, I have to suspect your ignition. Did you hook the vacuum advance and transmission signal back to the correct ports? (One is ported vacuum, one is unported vacuum)

-BC

Re: Installed new carb insulator= slightly higher idle?
 

Does this apply to a manual transmission?
I'm going to check the timing advance ports next.
At the moment I'm working on the O2 sensor. It seems it wont thread in!!!!:rolleyes:

Re: Installed new carb insulator= slightly higher idle?
 

Ok. I'll keep typing until I get 25 posts......:D

Re: Installed new carb insulator= slightly higher idle?
 

Get garage entries for your vehicles, and I may be able to add your vehicle tag to a signature for you. We can make an exception for someone's vehicle tag. The reason new members can't have signatures is because we were getting people join and post once or twice, then add spam to their signature.

Let me know once you've added your vehicles to the garage and I'll see what I can do on the admin side to add it as a signature for you.

Re: Installed new carb insulator= slightly higher idle?
 

Thanks! I'll let you know.

Re: Installed new carb insulator= slightly higher idle?
 

The O2 sensor seems low if reading below 2k rpm and a bit high 2500rpm. Not sure if I did it correctly but it was good and warm.
I think I'll just pop the universal unit in and roll the dice.
BTW the OEM O2 sensor was $215 :eek:

The fuel level was at the upper area of the sight glass, with only a small amount of air visible.
Did i read somewhere that the fuel needed to be between the two points in the center?

Re: Installed new carb insulator= slightly higher idle?
 

It should be in the dead center of the glass- maybe that is your issue.

It is easy to adjust the fuel level- just turn the screw on the top of the carb (next to where the gas line attaches) in very slowly- it will take some time to see the gas level go down because the engine must burn it.

Re: Installed new carb insulator= slightly higher idle?
 

That screw has the factory paint on it, that's what's confusing. :confused:

I'm getting a thread chaser for my o2 sensor, then look for the vacuum leaks.
after that I'll do the fuel level.

Re: Installed new carb insulator= slightly higher idle?
 

Yeah- its just painted on lock tight. Don't be afraid to break it loose and adjust it slowly.

Re: Installed new carb insulator= slightly higher idle?
 

The O2 sensor is on and started looking for vacuum leaks and I think I found one on the vacuum advance. There are two ports and only one holds vacuum.
I read somewhere that this is common to leak. :rolleyes:
Can anyone explain how these two ports work? I'm guessing each is set for a different carburetor port. So to give more advancement when that hugebutterfly fully opens. :D

I'll order another one and then reset the idle. I'm still going to check for vacuum leaks around the carb after I get this part on.

Any words of wisdom with the removing/installation of this particular part?

Re: Installed new carb insulator= slightly higher idle?
 

The last vacuum advance I had replaced was in my 74 Chevy C-10, but that was really easy once the cap & rotor were off. I wouldn't imagine it would be much different on your car. My recommendation is to have a roll of masking tape and a magic marker on hand to mark anything you disconnect so you are sure it goes back to its proper place.

Re: Installed new carb insulator= slightly higher idle?
 

Hang on a minute, I've never heard of a vacuum advance with two vacuum openings. Something isn't right.

Or do you mean that the carb has two vacuum ports?

You have to understand that most carbs have 2 vacuum ports on the front. One is exposed to manifold vacuum, and will always show vacuum (well while the engine is running).

The other port is called "ported" vacuum, and if you look inside the carb you'll notice that the vacuum port inside the carb is slightly above the butterflies - this is called "ported" vacuum because it only sees vacuum when the butterflies are open enough to expose the inside of that port to vacuum.

Your vacuum advance is supposed to be exposed to ported vacuum. I bet you put your vacuum advance on the manifold vacuum (which, by the way, will increase your timing at idle and therefore your idle speed)!

Go fix your vacuum lines and your problem should be fixed.

And if you have an automatic transmission, that will shift right again too.

-BC

Re: Installed new carb insulator= slightly higher idle?
 

This engine was designed by Honda to have manifold vacuum hoses connected to the vacuum advance.

There are actually two advance diaphragms in there. One works all the time and the other (I think it is the outer one) only supplies manifold vacuum when the engine coolant is below a certain temperature. This increases spark advance when the engine is cold. Vacuum is cut to this hose when the engine warms up enough.

Yes- you are right, that one diaphragm fails very often. Out of 6-7 distributors I tested at U-pull, only one was good. I priced the advance unit a few years ago and it was $50-60. If it is just the cold advance that is busted, then it would not be causing your wandering idle problem- but it would improve the way the engine runs during its warm up period in a few months when the weather gets cold.

If it is the main advance diaphragm that is busted, then you really should replace it.

Re: Installed new carb insulator= slightly higher idle?
 

I've been chasing this port all over the place! The problem is they make two different ones, one for the automatic and one for the Manual transmission. :(
I think I found one on line at Rock Auto.
I'll report back my findings as soon as I compare PN#'s to the factory Honda.

Re: Installed new carb insulator= slightly higher idle?
 

So far I struck out with the PN#. Rock Auto wants me to call back tomorrow and they will call the manufacture to see if it cross over.
Here's a link to the ones they offer for my Civic.

Re: Installed new carb insulator= slightly higher idle?
 

So, I guess you are crossing the P/N for Airtex/Wells?

Re: Installed new carb insulator= slightly higher idle?
 

Yes, the pn# Honda gave me doesn't Airtex/Wells.

Re: Installed new carb insulator= slightly higher idle?
 

Is this accurate for your car? I was trying to look on the Majestic Honda site for you.

https://www.hondaautomotiveparts.com/...b301_b0109.png

Re: Installed new carb insulator= slightly higher idle?
 

No, The Vacuum advance on mounted on the distributor, but has two ports like you have in the diagram.
Keep me posted if you find anything and thanks for the help! :thumbup:
Dean

Re: Installed new carb insulator= slightly higher idle?
 

Check out this site:

https://www.parts.am/Honda/findPart/6/110476

I've found the exact P/N on here, but you'll have to verify if the one's listed are more or less correct. It seems like the one for Airtex/Wells on RockAuto is for the A/T, not for your car being the M/T obviously.

Its linked to this submodel, w/ auto tranny:

https://www.parts.am/Honda/findPart/6/114955

Your P/N should be this one?

30104-PE1-830

It's the same P/N for all of the M/T, with only the Si having a different vacuum advance part.