Wierd idle problem... missfiring?

Lately I have been having a very wierd idle problem.

It has only been happening for about the past 2 months, but its wierd because it is intermetant (sp) and doesnt happen all the time.

ok, so here it goes...
Every once in a while, usually after a long drive, I will stop my car somewhere, like at the mall, at home, or something. And afterwards, when I get back in the car, usually after about 30minutes... I start the car, and it Idle's INSANELY rough. The idle seems to fluctuate up and down, lately only up and down about 200rpm, but before it was up and down a lot more, and the car would shake and shake.

Before it got to the point of almost stalling, and it scared me so I would turn off the car, get out and wait a while and come back, after trying a few more times. Then when I came back, it would usually work just fine.

Lately it hasn't been getting to the point of almost stalling, but it idles rough, at around 600rpm, and goes up and down a bit. But now when that happens, I can usually turn the car off, and if I start it up again a few minutes later, it runs fine.

Anyone have any clue of what could be wrong? I am out of ideas... Oh, and one last thing, which one of my friends pointed out the last time it did this; whenever it idles rough like that, if the dash lights are on, they seem to dim as the idle goes up and down.

Please help :help:

well the dash light will dim evertime you start up the car. I kind of have the same problem but not as bad and it happens very little. Check your plugs, wires, distrubitor, and might want to change the fuel filter too. Try using higher octance gas for a while to see if it helps. I know that in my moms van if you don't put 91 or higher it will idle like crap.

Ya, I just changes the fuel filter on the firewall a little while ago, only about 2 months ago... And its really wierd because it only happens every once in a while. I mean it will run fine for a few weeks, with no problems at all, and then it will start acting up.

what about you spark, is that all good. I'm thinking it might be just some bad gas.

I've been having the same problem too... cant figure out what it is, it would be nice to know, even though it hardly ever happens.

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what about you spark, is that all good. I'm thinking it might be just some bad gas.

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I really doubt its bad gas... I have been through about 10 tanks of gas or more since this started happening, and it still happens. I also thought it might be water in the gas at one point, so I threw in some gas line antifreeze, and it still happens.

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I've been having the same problem too... cant figure out what it is, it would be nice to know, even though it hardly ever happens.

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Finally, someone else with the same problem... i mean its not a good thing, but maybe together we can figure this out. lol... I am actually going to pull my car in to the garage today and check the ignition stuff... plugs, wires, cap, rotor. Maybe I will take my ignition control module in to work and test it... who knows, that could be the problem.

Well, i am guessing for me it isnt the plugs/wires/coil... their all new.... i've tried to figure out if there is something in particular that goes on, ie weather, time driving, etc, but i cant really seem to find anything.... although it only seems to happen when the car is warm... i guess i am really stumped on this one. i think mine might be a little worse then yours at times though, cause mine will usualy die when it does this.

Mine would usually die, or close enough that i didnt want it too and I would shut off the car before it did.

And I dont know what I'm saying, because my plugs, wires, cap, rotor were replaced not even a year ago.

I am experiencing the same thing... it onyl happens when the car is warm, but I cant connect it to anything else. I thought it might be the cold weather, but it happens on warm days as well, and only when the car is warm... damn im confused.

Hey Rex, do you have msn? if so PM me, so we can try and figure this out.

I have a somewhat similar problem myself, my car will idle somewhat rough when it starts and then about 20 seconds later it will go down to about 200 rpm, when the car warms up, it is fine though. I THINK my problem has to do with the fact that the rocker valve gasket has been leaking oil into my spark plugs for over a year, the guy before stripped the spark plug casing (lucky me). I would agree "Justin86" to check your spark plugs and ensure they appear in good condition. Otherwise I would guess that condensation from the engine being warmed is cause a bad idle, and when the car warms up, does the idle get better?

If the idle does get better after it's warmed up. Just for testing reasons, put a blanket(old crappy one) over the engine after you shut off the car and take the blanket off before you start the car again and see if the car starts better. I realize this doesn't sound like the most intelligent idea, its an idea someone gave me. I'm not really that auto intelligent

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I would guess that condensation from the engine being warmed is cause a bad idle, and when the car warms up, does the idle get better?

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Whenever this happens, the engine IS warm. It is usually after a long drive, then i will get out, and come back to the car and this happens.

Yesterday when it happened when I went to pay my ticket, I got back in the car, started it up, and because it was happening i decided to pop the hood and take a look... and when I did, I saw that the engine was shaking like crazy.. like when you start your car, it will shake, and it was like that, but the car was running, and the idle was staying around 600rpm, but going up and down about 100rpm.

well I looked into my very handy service manual at the trouble shooting. "irregular idle" @ "after warming up" = (ECU)-faulty ECU. (INJECTOR)-open/short circuit, stuck injector. (FAST IDLE MECHANISM)-stuck air bypass valve. (CRANK ANGLE SENSOR)- open/short circuit, faulty sensor. (MANIFOLD ABSOLUTE PRESSURE SENSOR)-open/short circuit, faulty sensor, broken/disconnected hose. (IDLE CONTROL SYSTEM)-faulty solenoid valve. (OTHER)-check ignition system (sparks), and each injector. Possible to start by operating throttle? (stuck air bypass valve)
Have fun! :wave:

For mine i can rev the engine and it revs fine... i usually rev it to 1.5k and let it sit there for like 20 seconds... after that it is fine

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well I looked into my very handy service manual at the trouble shooting. "irregular idle" @ "after warming up" = (ECU)-faulty ECU. (INJECTOR)-open/short circuit, stuck injector. (FAST IDLE MECHANISM)-stuck air bypass valve. (CRANK ANGLE SENSOR)- open/short circuit, faulty sensor. (MANIFOLD ABSOLUTE PRESSURE SENSOR)-open/short circuit, faulty sensor, broken/disconnected hose. (IDLE CONTROL SYSTEM)-faulty solenoid valve. (OTHER)-check ignition system (sparks), and each injector. Possible to start by operating throttle? (stuck air bypass valve)
Have fun!

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Hahahah, thanks... thats so many things it could be, but I guess its a nice start. I have a strange feeling it is something with an injector, but we'll see.

And Rex, I can rev mine fine as well, but as soon as I let off the throttle it starts idling rough again, but if I hold it around 2k for a minute or so, it sometimes stops.

Oh, and BTW, Justin86, what manual do you have that you are reading this in? it sounds like some very helpful information.

They very expensive and hard to get Honda Service Manual. You might be able to get them on ebay for $50 and if the dealer still has them it will be even more. There is a reason why the chiltons and haynes manuals are so cheap, cause they are crap.

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Originally Posted by Justin86

They very expensive and hard to get Honda Service Manual. You might be able to get them on ebay for $50 and if the dealer still has them it will be even more. There is a reason why the chiltons and haynes manuals are so cheap, cause they are crap.

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:huh: holy crap, i paid $5 for mine maybe i should take alittle better care of it

I would try cleaning the throttle body real well, check for ECU codes when it idles crappy, and also try using some gas line antifreeze additive. Does your gas cap hold pressure?

hmm, I would run some injector clean just for shits and giggles...It could just be that there is some "gum" build up in the injectors causeing it not to spray as well...possibly check your o2's, they could be going.

I have the same problem with my 89 Accord SEi. I have had it for a couple of years and it happens every time I drive it on the interstate, shut it off and start it again a few minutes later. I'm sure it is heat related and I can eliminate the crank angle sensor as the cause because I have replaced my distributor during this time as well as both oxygen sensors and it did not help. I did not replace these items to try to fix this problem. It was for other problems. I can say that it does not bother me much because I can just run the engine at a higher rpm for a few seconds and it goes away. The engine shake is a result of rough idling.

hmm, heres an odd one, but it was an issue on my friends nissan...tighten all the engine mounts...when his got loose, it would seem to idle rough, but was just shaking alot.

Mine is idling rough because the rpm's drop to around 200. I think it is heat build up in the engine after it stops causing the air/fuel mixture to be incorrect. Could be a sensor failing as well.

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Originally Posted by Justin86

They very expensive and hard to get Honda Service Manual. You might be able to get them on ebay for $50 and if the dealer still has them it will be even more. There is a reason why the chiltons and haynes manuals are so cheap, cause they are crap.

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Ummm, you can go to any Honda dealership and order the shop manual and the electrical manual, at any time - same stuff they use. Helms Inc is the one who reprints it for them. It's the same price on the Helm Inc website as at the dealership, but I don't know if you have to pay shipping or not if you go through the dealership.

http://www.helminc.com Choose your make, year, and body style. It's an original looking manual w/ the supplements - usually on the seatbelt. Shop manual is $59; electrical manual - which looks like a bad xerox copy, but still worth it - is $39.

Easy huh?

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I would try cleaning the throttle body real well, check for ECU codes when it idles crappy, and also try using some gas line antifreeze additive. Does your gas cap hold pressure?

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Had the whole upper intake and injectors cleaned a few weeks ago, and whenever the rough idling happens now, it seems to not be quite as rough, definately not to the point of stalling any more. I tried gas line antifreeze, and yes the gas cap holds pressure quite well.

And I really should check the ECU for codes, I have a feeling that could be the problem.

Did you change the fuel filter ?, also, have you bled off the cooling system ?...The IAC could be bad or 'vapor locking' on the coolant side of things.

I had that problem it turned out to be my fast idle valve was not closing all the way and my IAC was tring to compensate. Also on a side note Changing the oil also seemed to really help the situation (weird huh). It is all good not I got a fast idle that closes altho it is weird durring fast idle. Fortunately majestic honda is on it's way tih a new one.