Car idel question..

[Nedar]

I know lot of you here are just as proficient with cars as you are with bikes. I have a 98 honda civic which has some minor idel issues right now. In the past few days I have noticed that during cold starts in the mornings the cars idels rough, usually goes up and down but after giving some gas it finally settles at a very low idel. When the car is warm and driven long the car idels very low almost to the brink of shutting off. Any suggestions how to fix this??

[NiceGuysFinishLast]

Increase your idle speed. Hah, sorry, had to, I have no useful input, but free bump!

[redciv1]

When you say up and down do you mean + or -500 rpm or + -1000 rpm? Probably try basic tune up also making sure that air filter is not gunked up with dust pollen and everything else.

[Nedar]

When you say up and down do you mean + or -500 rpm or + -1000 rpm? Probably try basic tune up also making sure that air filter is not gunked up with dust pollen and everything else.

Thanks for the bump. when i first start when its cold it will go down to as low as 100-200rpm for a minute then jump up to around 2000rpm then slowly come down to about 500rpm and settel there. All other time its around 500rpm. is it easy to increase the idel speed? I would like it to be atleast 1000rpm. I had a tune up done about 3000 miles ago. Could it be fuel filter clogging up or sensors?

[Gmoney]

probally some senor in the intake gunked up .. like TPS

[Lazarus]

Is it stick or automatic? Sounds like you might have a vacuum leak. Get a can of starter fluid, start the car, pop the hood and start spraying your hoses, covers, all over the place. If you hear the car rev higher when you spray thats where your leak is. Now if you dont hear anything it still doesn't mean you dont have one. I had to take my Spec-V to 3 different dealership before they found out the vac leak was at an injector o-ring.

[Nedar]

Is it stick or automatic? Sounds like you might have a vacuum leak. Get a can of starter fluid, start the car, pop the hood and start spraying your hoses, covers, all over the place. If you hear the car rev higher when you spray thats where your leak is. Now if you dont hear anything it still doesn't mean you dont have one. I had to take my Spec-V to 3 different dealership before they found out the vac leak was at an injector o-ring.

Its manual transmission. Hmm i suppose there is no quick fix for this. Will take it into a mechanic this week.

[Lazarus]

My money is on a vacuum leak. You can try doing what I suggested. A can of starter fluid is only a couple bucks. Might save you some money if you know what it was that was causing the problem, even if you have the mechanic do the work.

[Gmoney]

my money is not on vacumn leak :)

[Lazarus]

my money is not on vacumn leak :)

Well my money isn't on a TPS since he didn't mention any hesitation.

[Nikk777]

Are you sure the tune up was actually performed? Happens quite often where they charge you and do nothing or just put a bottle of fuel cleaner in. New air filter, plugs and wires are never a bad idea along with a can of fuel treatment. Still have the issue, then start exploring the vacuum/sensor issues.

Take a plug out and look at it, post a pic, etc. See how they look and go from there.

[wallypiper]

My ranger does that when the idle air bypass valve doesn't open. You just clean it and it starts working again.

[MX Tuner]

+1 on the idle valve getting carboned up. A vacuum leak would typically give more consistent symptoms. A bottle of $2 fuel additive can help clean dirty injectors which can give a variety of symptoms. The throttle plate can get deposits collecting around it and can give poor idle symptoms with a hot or cold engine.

A TPS may not give a hesitation if it is faulty. There are a multitude of ways a TSP can fail. Even if it fails completely, some injection systems are so good at providing missing info, some owners don't realze there is anything wrong.

[mtelam]

Try starting your car while its hooked up to another car battery. Jump it basically. If it doesn't idle rough then drive down to your parts store and buy a battery! I had the same issue and it cost me $200 bucks to find out it was the battery. THEN I had to replace it. ugh...

[BadAssRX-7]

+1 on the idle valve getting carboned up. A vacuum leak would typically give more consistent symptoms. A bottle of $2 fuel additive can help clean dirty injectors which can give a variety of symptoms. The throttle plate can get deposits collecting around it and can give poor idle symptoms with a hot or cold engine.

A TPS may not give a hesitation if it is faulty. There are a multitude of ways a TSP can fail. Even if it fails completely, some injection systems are so good at providing missing info, some owners don't realze there is anything wrong.

+1 on BAC (bypass air control) valve. this unit main function is to step up the idle when needed..... large load on the alt., ac is on ect. and they do crap out some times cus they are in the intake and do get carbon buildup.

and on the tps... my 89 rx7 has a 2 stage(2 sencers on 1 plug) tps. 1 is an "idle" and the other is full range. this is a real pita becuase if they are both out of spec high, or both low you can adjust it back into spec but if 1 is high and 1 is low you get to buy a new 1000$ tps. My system has a summer and a winter time issue. so i have to adjust the tps when it sets in hot temp or cold temps. I just reset it about 3 weeks ago. I get a jumpy cold idle and when warm it likes to hang about 1200rpm unless the air is on. after i adjust it all is good.

and yea I have found about 80% of the time when im not the person working on it that they dont do what they say they did. Hell even a good friend screwed me when i lowsided my bike. he repaired the damage and i ordered a ton of stuff and got it to him and had him put it all on. and he said he did and even adjusted the valves... like a car style adjuster is what he said it had... not like the shims it really does have. and I even paid him 900$ when he said he would do it for free. I just gave him 100$ every week or so. He didnt say much when i told him to bring me my uninstalled parts so I could install them. So I dont trust ANYBODY. call me a PITA I tell people/ shops that i want to see the old parts when i come to get the item needing repair. and have busted a few shops when they tried to slip diffrent stuff in on me... I know my cars and stuff and know what they have in them. so unless u watch them work on it dont trust them.

[Lazarus]

Any update OP?