Question about Honda Civic

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1998 Civic, Cold start, idles fine. When car is warm idle speed increases then decreases over and over again from about 600 rpm to 1100 rpm. once warmed up and driving throttle becomes on-off switch...motor accelerates and slows depending on throttle opening. runs smooth until I get stuck in traffic or a long stoplight. I shut motor off when coasting or at rest, re-start, runs smoothly again. Problem increases when weather is at or above 40 degrees F.

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  • Honda Master
  • 3,187 Answers

It could be the MAF sensor or the air temp sensor, it could also bet the idle sensor, it would be best to put the engine on an ecu reader to read live data as it would show at what temps the senors are working at some times it may not trigger a fault, but live data will tell you at what temps the sensors are say they are and you should be able to see what one is not working right. i would think it would be Maf sensor when was the last time the air filter was changed. if its really dirty change it and also use some MAF sensor cleaner you can buy it from a range of places and clean the MAF sensor. be careful cleaning it only use the recommended maf cleaner as other chemicals will damage it. remove the sensor from the rubber pipes a spray the cleaner on the the sensor an a bit of paper towel give it a good clean with the spray and leave it to dry before refitting. some people use carb cleaner but would not recommend it.

Posted on Jun 21, 2017

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Posted on Jan 02, 2017

  • 81 Answers

SOURCE: stalls and wont idle when cold

Re the trooper. You have a couple of possibles. The most likely is the glowplugs or glowplug relay. Don't be fooled into thinking glow plugs only heat to start - the also do whats called postheat. That is to raise the cylinder temp until the block is warm. IF they are not functioning (clip a light onto one whilst switching the glowplug on to test the relay) this is common.
Most likely is a stuck EGR valve - stuck open so running a very lean mix when cold. Its two bolts on the inlet manifold, pulls out and looks covered in soot - it should push in and spring out. Can be cleaned in petrol or alcohol or with compressed air.
More remote is possible you have a faulty injector...only really testable by an engine centre...

Posted on Jan 26, 2009

  • 12 Answers

SOURCE: rough idle / engine surges until power is applied

Sounds like a possible vaccume hose leak?

Posted on Feb 07, 2009

skidoorev
  • 11 Answers

SOURCE: Trans shifts very hard after 5 minutes of stop and go traffic

A reason for hard shifting could be a problem with many things with various degrees of seriousness. It could be your ATF( automatic transmission fluid) is low or broken down and old. This would cause the hardness and the reason for stop and go traffic effecting it. Another possibility is your transmission is just shot, and the timing gears inside are worn and not properly shifting at the correct RPM causing a **** during shifting.

Some possibilties, not all!

~Lucas

Posted on Mar 27, 2009

  • 77 Answers

SOURCE: Car starts fine..Idle is fast...stalls after car warms up

Check for vacuum leaks. Also try cleaning the ISV.


If that doesnt work go to vwvortex.com and post your issue there

Posted on Jul 08, 2009

  • 1509 Answers

SOURCE: rough idle then stalls

Vacume leak or bad idle motor. With the car in park and running with the hood open listen for leaks moving your hand around the different hoses looking for a change in the sounds that you hear. The idel motor also makes the car idel up to 1500 RPM or so right at start-up then idel down, If it doesn;t the idel motor is likly. Check engine light is on when running? Test for codes, Follow code test charts don't skip any steps!.

Posted on Nov 02, 2009

Testimonial: "Found the problem vacume leak like you said."

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Hi Joseph, When starting the vehicle from cold in cold weather, the RPM can be as high as 1300 and in temperate climates about 1100 RPM. The RPM will drop to normal as the coolant is warmed. Normal idle speed is between 750 for Auto and 650 to 700 for manual transmission. Regards John

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Engine idling varies depending on light or aircon is on/off


dude its normal for first start or cold start that the idle is ok but it must high than normal... its normal because the engine is warming up it self... when it gets warm, the idle speed will return normal idle... your engine is 1200cc, it has not much HP for a great load... and i know its a carburatored engine and its an old engine, your head lyt and a/c fan and aux fan and all the electrical system on your car, uses the HP of you engine and its a lot of load to the alternator driven by the engine to generate an electricity they need and thats why the engine rpm speed lowering down to dead and its shake. thats why when you use your lyts or all electrical, you engine is weakening... the best remede is adjusting you idle speed... its located behind the carburator.. its a small black knob.. just make a twist each eighter way and you'll find out if your idle rpm speed ts incresing or decresing.. just increase it and try opening your lyts and other electrical, if its still shaking then adjust it a little more

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1 Answer

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Problem might be the air control valve, it's located at the right side rear of intake manifold and has a hose going to the air intake duct from the air cleaner, as a test you might try pinching off that hose when the idle is a problem.

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