I have a 1985 honda Civic with 220,000 miles. This car is my all time favorite! It has always been a reliable car, but about 6 months ago it stopped revving above 4000 rpm. The Power band stoped above 3,000 rpm and would just bog and buck if you went any higher. As of today it has gotten worse. It will no longer rev above 2500 rpm. Now I have checked the distributer cap, checked the fuel pump, timming, but have not been able to find any obvious answers. Does anyone have any insights as to what might be wrong?
I have replaced the PCV valve (which was recommended) - and the car idels beautifully - but still will not rev high. (i invented a cool pcv extracting tool - will post photos)
- I checked the exaust and i believe it is not blocked. I put my hand over the exaust pipe, and i felt pressure - as you would expect - i guess this means the back muffler is ok. anyone think the catillitic converter could be stuffed?
-I made an adjustment to the timing - and the car is now accurately timed.
- When i full throttel the engine (it refuses to go above 2500 rpm) the carb spits a mist of gas out of the butterfly flap - wtf could this mean?
ill see if i could post a video of it running to give everyone a good idea of whats going on - now what do i do next?
thanks everyone!
___________________________________________________________ SOLVED - It was a Blocked Calytic Converter! - Thanks again everyone!
Make sure the butterflies open properly. Basically, with the car off, look down the throat and pull on the throttle cable. Also, if you have a vacuum pump, with the engine off and throttle held wide open, apply vacuum to the secondary actuator and make sure the secondaries are also opening properly.
The carb spiting a mist of gas out of the top is the clue that there is a problem in the exhaust. Unhook the exhaust at the front of the catalytic converter and test.
I would say it would be the adjustments on the carb. I'm not a carb guy but on different vehicles that I have had when the carb is not right it won't speed up right, top out early and reving would be affected. Good luck either way on finding out what it is.
Probably wouldn't hurt to change the fuel filter, if it hasn't been done in awhile. I had a similar problem where it would bog at around 5k, it was the fuel filter.
On an old car like this there are two culprits that can cause about 90% of the problems-
#1- The timing belt #2- The butteryfly in the carb/throttlebody. Both types of cars have a similar arrangement that acts as the "throttle" by limiting the amount of air going into the intake manifold.
I would start with a can of "carb cleaner" and spraying it liberally in to the carb to free up the gunk that has built up in there.
Then I would check your engine's cam timing. If the belt is old, it can slip and cause this kind of problem.
Thanks everyone for all the input!!! Here is a video of it running so you can get an idea of how it is acting. Each video is about a minute. You can see the gas spitting from the carb and hear it running rough. The car is timed - so that is not the culprit. All the elctrical looks good - inclusing the points on the distributer cap and all the internals be hind it. Fuel pump is good as well as the gas filter.
video 1 : video 2 (it running):
Euforic blue - thanks for the input. I actually did dump a can of carb & choke cleaner in there. Everyhting looked pretty good. I however did not check the secondary vacume actuator. (That actuactor had actually stuck open once and stuck the throttel on the car about 6 years ago.) If I can diagnose the problem down further i will check that right before i pull the carb. Look at the video and let me know if you still think that is the problem
Jeff - i think you hit it. I agree with you (thanks for the updated reply)- but am in a bad spot because that catlytic converter is rusted to say the least, and if i pull it i will break it. There is no way to get the exaust manifold off - no way - with out breaking the bolts. I had replaced the exaust pipe up to the elbow that connects to the catilitic converter - what would you think if i disconnected it there and stuck a coat hanger up there to try to free up the ceramic honeycomb that might have broken loose? when you say "disconnect at the front of the catlytic converter" you mean the top right? Have you ever heard of c-converters getting stuffed up before?
86 hampster - thanks for the input. the carb could be a problem - but i dont think it explains the spiting gas. Ill keep my eyes on it though. any more ideas?
rpr - the fuel filter would have been one of my first notions, except for the fact that i replaced both of them last year. I know in theory they could get clogged quickly, and with the price of gas i run on empty more often now then i ever did before. Look at the video and let me know if you think i should still pull em
Scott - that is an excellent realization. 2 of the major problems i have had over the years with this car have been what you mentioned. THe timming belt is in great shape - i had it off a few days ago - and the timming is perfect. As for the butterfly the initial flapper is ok, beneath it i am not sure though. If i cant diagnose the problem - i will rebuild the carb.
marcus - that was my initial idea too - but timming looks good.
thanks everyone for your help so far! please check out the videos and let me know your input.
thanks!
Edited by 1985 CiviC 1.5 S, 14 August 2008 - 01:38 PM.
Jeff - i think you hit it. I agree with you (thanks for the updated reply)- but am in a bad spot because that catlytic converter is rusted to say the least, and if i pull it i will break it. There is no way to get the exaust manifold off - no way - with out breaking the bolts. I had replaced the exaust pipe up to the elbow that connects to the catilitic converter - what would you think if i disconnected it there and stuck a coat hanger up there to try to free up the ceramic honeycomb that might have broken loose? when you say "disconnect at the front of the catlytic converter" you mean the top right? Have you ever heard of c-converters getting stuffed up before?
Is your catlytic converter like this? If so remove the two bolts and push apart and start your engine to see if this was the problem. No need to remove the exhaust manifold. Replace bolts if they break. Jeff
Is your catlytic converter like this? If so remove the two bolts and push apart and start your engine to see if this was the problem. No need to remove the exhaust manifold. Replace bolts if they break. Jeff
The cat is right on the exhaust manifold on the carbed cars, I wish it was as easy as the Si.
I love Youtube for these types of situations! It gets you so much more info than just a description.
In this case though I'm still stumped... I'm with the rest on what it could be; I can't see it being anything other than either a major problem with the carb or a clogged (and nearly blocked) cat or exhaust.
The carbs on these cars always need a rebuild after this much time anyway, so it certainly can't hurt to do it. And if that's not it it just has to be a clogged up cat/exhaust system.
im under the car right now. jeff - thanks for the picture - but unfortinately dark hand is correct about the location of the c-converter. im gonna attempt it while u guys r reading this. i did just find a loose spark plug - although i dont think this is the main problem - i think it will help.
Ok you have this type I would drill and chisle the catylist out if you do not need an inspection in your area. Jeff
A bit destructive but that would do it! The O2 sensor is before the cat, you could pull that out and see if it makes a difference. Maybe even get a light down there to take a look. If that helps, you've found the culprit. You might have a bit of flame and a bunch of carbon shooting out the hole so you'd need to be careful and only run the car a few seconds, but that's all it would take anyway.
Although getting the O2 sensor out is almost as hard as removing the cat sometimes!
i love those pictures - so illistrativly descriptive! So i pulled the spark plug cleaned it up and put it back to see if it was the culpret - and same deal. still stuck @ low rpm.
Darkhand - that is an excellent idea to pul the o2 sensor. That is exactly what i am going to do now. Glad i checked this before i dove into the catlitic converter.
jeff- with the 02 sensor out i can then gut the thing with a coat hanger through that hole without having to pull the unit off
Movie Time! (darkhand - sorry if i got ur name wrong in the film )
this is a possible diagnosis confirming it is the calitic converter. I am not sure if my logic is correct though. I think i am going to have real difficulity pulling either the 02 sensor or the catlytic converter - but atleast this could possible confirm it.
any input?
I just confirmed that that port should suck not blow via my repair manual. now what?
Edited by 1985 CiviC 1.5 S, 14 August 2008 - 05:31 PM.
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