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Peter Bagley
Peter Bagley, Toyota mastertech
Category: Honda
Satisfied Customers: 777
Experience:  master tech at Toyota dealer
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Are you a real person? or a computer? I have some problem

Customer Question

are you a real person? or a computer?
JA: I'm an assistant to the Honda Mechanic. I work with them to help customers like you.
Customer: I have some problem with my honda. I used this site before.
JA: What is the model/year of your Honda?
Customer: 1987 honda civic. manual cabureted/
JA: Are you fixing your Civic yourself? What have you tried so far?
Customer: I have been fixing my honda for last 20 years, except for one time that I have to ask question on your site.
JA: Anything else you want the mechanic to know before I connect you?
Customer: well the problem is on idle. it is quite rough. from 2000 rpm to die.
JA: How many miles are on the car? What size is the engine?
Customer: I scratch my head. 1.5 l engine.
Submitted: 1 year ago.
Category: Honda
Customer: replied 1 year ago.
This needs to be on or beyond expert or professional level. My mechanic level close to expert level, on my own car in my spare time, at home.The car is 1987 Honda Civic Wagon. Front wheel drive. 1.5 liter engine. Carbureted. It has 420K miles on the odometer. The carburetor needed a rebuild back in April which I did. After that I found the idle is very rough. I adjusted as high as 2000 rpm but it still dies. It seems like it will die as well even if I set to over 2000 rpm. Usually it is up and down within 500 rpm. I have a second carburetor so I installed the second carburetor but it does the same thing, in a little smoother way (ie, it dies not as rough or sudden as the first carburetor). So it is just a slight different characteristics of a carburetor. Because both carburetors have idle problem I figured the problem may be not just on the carburetor itself. It is gonna be on something else too. Checked all the vacuum hoses and they are all connected correctly. Also that primary slow mixture cut-off solenoid valve is good, although I am not sure how it works.One thing worth mention, there is a small pop sound (like sound of a fireworks but not that loud). Although repair manual says about PCV valve on this car but I can't find that PCV valve. The noise is from around the right side of the carburetor area but I can't locate where that pop sound is from. It didn't have that before the carburetor was rebuilt.There are two black plastic boxes where there are vacuum hoses coming out of them and connecting to various parts of the carburetor, one is on the right side of engine, and the other is on the passenger side of firewall. I opened the covers and did some visual check. I don't see anything wrong. There are several small air filters inside the boxes, dirty but I don't believe clogged.
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

This may still be an issue with a vacuum leak on your engine here.If all vacuum hoses were or are checked and found o.k. the fault can be with leaking intake gaskets or carburetor gasket leaking allowing excess air to enter the system.I have also seen brake boosters leak and cause this fault.The pop noise can be a result of excess air in the engine causing a lean running condition.

In some cases this can require a smoke machine to do a smoke test on the engine to locate any hard to see leaks like intake gaskets leaking.I would check/test the engine further to locate any leaks needing repaired.If this is or has been done and found o.k. let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
Thanks Pete. I will poke around this week again and make sure it indeed doesn't have vacuum leak.
Expert:  Pete replied 1 year ago.

Your welcome

Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.Your 5 star rating is appreciated

Thanks Pete

Customer: replied 1 year ago.
Hi Pete,Although I don't think there is a vacuum leak I went ahead and did a smoke test. There is no leak at all. The carburetor gasket doesn't leak, nor the intake (intake has its own gasket. It was sealed during last job with silicon. The carburetor gasket was sealed with black silicon sealant). The brake booster doesn't have leak either (the brake still works).In my opinion it shouldn't be an issue with vacuum leak, or more than just vacuum leak. The idle does hold but just up and down in a plus minus 500 rpm range (not consistently. I would say the frequency is up and down once every 10's seconds). It does go beyond that 500 rpm range, and die. I would say it dies several times when I make a 5 mile trip.I know that primary slow mixture cut-off solenoid valve is to hold idle but when I disconnect it the idle doesn't change at all. So it is gonna be something else. I am thinking it maybe one of the diaphragms, or even a vacuum pump.
Expert:  Pete replied 1 year ago.

This is a difficult question for me to diagnose myself here.

I will open your question up for others here to see if someone else can assist further on this as there may be others here that may have more info on what to check or do with this issue.I hope you can get this resolved with ease.No need to reply to my last post here unless it is a last resort as it will keep your question locked to me and others will not be able to view it.If you feel you want to continue to work with me on this feel free to reply at any time but keep in mind in some cases it can be difficult to fully diagnose or help repair this without seeing your vehicle.

Thanks Pete

Expert:  Peter Bagley replied 1 year ago.

Hello and welcome to just answer and allowing me to assist you, first may i ask a couple of questions to get a picture of what I'm dealing with. I know you don't think it's a vacuum leak but can uoy put a vacuum gauge on it to read the manifold vacuum ? this can tell a few things such as a lek , timing and or mixture adjustment. even though the carb was rebuilt and or replaced the mixture may be too lean . so can you please get that vacuum reading before we proceed thank you.

Customer: replied 12 months ago.
Thanks Peter.What do you mean 'manifold vacuum'? From the air intake? When piston is on TDC position? Otherwise how to read vacuum?
Expert:  Peter Bagley replied 12 months ago.

when the engine is running it creates a vacuum necessary to draw air and fuel into the combustion chamer and it should be around 20 in/mercury If it is lower or erratic it can give you those systems. you need a good vacuum gauge to read it and hook it up to a manifold port to read it.

Customer: replied 12 months ago.
you mean to get the reading when the engine is running? it won't run though, but at least turn the ignition on and read. Is that what you mean?Not sure if you read the whole thread since it is getting longer and longer. The engine starts fine. The issue will come when the engine is warmed up. It doesn't die right way, nor dies all the time. It just doesn't hold the idle well, and when it idles on the low side then it dies sometime.
Expert:  Peter Bagley replied 12 months ago.

I'm getting mixed statements here perhaps a phone session would clarify things

Customer: replied 12 months ago.
I have to work during weekdays so writing is the best option for me.Which part is confusing? I can explain further if you give me some clue.Just give you some of my background on autos. I am not a mechanic, nothing even close. It is just my hobbie. I don't have any fancy car in my fleet. The newest one is 1993 Nissan Altima. For my life time so far I haven't spent one penny in an auto shop for last 20+ years and I do everything by myself, including engine rebuild, except for wheel alignment and tire (just don't want to spend thousands of dollars to invest, and use only once every few years). So try me the best you can.
Expert:  Peter Bagley replied 12 months ago.

ok the thing that was confusing to me was at one point you said it was running and the other time you said it won't start? what is it can you get it to start even for a short time? Here is a link to effectively checking for that vacuum leak which can be done on any type of engine also you can hook up a vacuum gauge to any port on the intake that has a tube going to it for that check. Also even though you had the carb rebuilt or replace the idle mixture can still be off and you can adjust that. but first do those checks.

Customer: replied 12 months ago.
Thanks for the information. I will watch the video and check vacuum again tonight after work.The thread is getting quite long.The car starts normally. The idle issue appears only after the car is nicely warmed up. Usually it take about like 5 minutes for car to warm up, shorter in summer (I always let it warm up before I start driving). The idle at that time (from this point on the car is warmed) is plus minus 500 rpm. I set the middle point around 1500 rpm. The up and down of engine speed happens about every a few seconds, like maybe 5. So it is not in a vibration fashion. Think the up and down motion of the hand on the tachometer is like the second hand of an analog clock. That is how often the speed varies. Sometimes it goes below 700 rpm, then dies. That happens even less often. maybe like every few minutes, or several times when I make a 5 mile trip. This make me scramble when I am at a stop light, or make a turn or so on. Once I re-start the engine it fires right up.Hope it summarizes it.I will let you know the result.
Expert:  Peter Bagley replied 12 months ago.

great I'll get back when I read your findings

Customer: replied 11 months ago.
Hi Peter, I tried the method from the link you provided. The result is not conclusive. Because the car has idle issue so I can't really tell if the idle fluctuation is caused by my test or by itself. To eliminate the last possibility I ordered a carburetor insulator since this one is quite worn out with all the cracks and uneven surfaces. It will arrive in a week. I will post the result at that time.
Expert:  Peter Bagley replied 11 months ago.

that would be a good idea , I'll wait for you then.

Customer: replied 11 months ago.
Hi Peter, Sorry for the delay. There was a rain/wind storm, then rained quite bad so my work is on and off.
I replaced the flange/insulator beneath the carburetor, and replaced all hoses connecting to the carburetor directly, and others as many as possible. It is better now but the idle still can't hold. It can go down to about 1200 rpm without dying (before above 2000 rpm). I used the method you recommended from youtube and it doesn't seem affect the engine speed. I am gonna go to a Napa store nearby tomorrow and buy a bulk of vacuum hose and replace rest of the hoses even the ones far away from the carburetor see if it helps. At the mean time if you have any ideas please let me know.
Expert:  Peter Bagley replied 11 months ago.

did you check the idle mixture screws that they are set right? give you a link how to check for vacuum leaks

Customer: replied 11 months ago.
is the youtube clip the same as the previous one to test leak?I never touched the idle mixture screw. sure I will take a look.
Expert:  Peter Bagley replied 11 months ago.