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I have a 97 honda civic LX 1.4L non vtec. Once car is warm it begins to idle very low at stop lights/signs. Seems to run fine during regular driving. Has a sputter from muffler. Has CEL light on. Shows 2 codes, One code that it shows is p0303. Has another but cant remember.

Put new NGK spark plugs and new wires. New distrubuter cap and IACV. Also cleaned throttle bottle very well. Still having same issue. Was reading some stuff about EGR vavle.... Any advice on figuring out what it might be and if it may be the EGR valve.? Thanks for any help

 
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anyone? any suggestions?

 
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This topic has been absolutely murdered on this forum. There should be a sticky about the idle issues that these cars have and the most obvious solution(If there is, I'm sorry). I'm going to try and remember them all right now even though I just worked a 12 hour shift.


I'll start by saying, if the car is throwing a check engine light at you. It's crying for your attention. So go give it the attention it deserves, and get the codes checked. It might actually tell you what's wrong with it!
The most common idle issues are caused by: and resolved by:

1. Dirty throttle body and the sensors and valves that surround it. The best way to clean your throttle body is to actually remove it from the car and spray it with throttle body cleaner. Remove all the sensors and spray them with the stuff until they are clean. Be careful with the TPS sensor as it's very hard to calibrate, I suggest not cleaning or messing with it. If one of the sensors is actually defective it will cause crap idle, most of them will throw a check engine light.

2. A vacuum leak. This generally happens when a hose starts to leak around the intake manifold because it gets old and loses it's integrity. It is also caused by shot gaskets such as the intake manifold gasket itself The best way to check for a vacuum leak is to have the car idling and spray the throttle body with throttle body cleaner at various spots (1 spot at a time so you can pinpoint the issue). You will notice an RPM change if there is a vacuum leak after you have sprayed the said spot.

3. Spark issue. If the spark plugs, wires, cap and rotor are old... Change them before anything else because they are effin' cheap, and part of the regular maintenance of the vehicle. So change them, cheap ***. (I know you changed them, I write this in case someone actually searches and stumbles on this thread). On a 7th gen the culprit might actually be a coil pack.

4. Clogged fuel injectors will cause crap idle. I would probably resort to this last after the things above because you can't really clean them yourself... I wouldn't anyway. You will often get a cylinder misfire code if you have clogged injectors.

5. Change your air filter... Every car needs to breathe.

Now for the expensive stuff:

1. Timing is off. This is a bit more expensive to fix and can destroy the engine if it's not fixed. I think on your engine you can adjust the timing without removing the timing belt which is nice. It's important that you get this fixed A.S.A.P. if it is the problem because you can destroy the engine if you don't. You have to take it to a shop to diagnose properly, tell them to check the timing.

2. Compression loss. Something is messed up, either head gasket or piston rings are causing you to lose compression and making the car idle like sheeyat.

3. Head gasket failure. When a head gasket fails the cylinders get injected with water or coolant and make the car idle like sheeyat. You can tell this by looking for white in the exhaust, and sometimes the coolant overflow reservoir overflows. Almost a dead giveaway of a failed head gasket.

4. A bent valve. Not sure how... but this would definitely cause crap idle. Along with a popping or ticking noise that goes with it.

5. Distributor is toast. Not delivering spark when and where it should cause crap idle.

I'm too tired to think, I'm going to sleep. I'm sure someone will have more to say about this at a more reasonable hour!!

Hope this helps.

Get your codes checked and it should tell you where your problem lies.

 
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P0303 Cylinder 3 Misfire Detected

You are misfiring in cylinder #3, causing crap idle.

 
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Thank you for your post. Ill get the other code pulled. Do you think with the syptoms the vehicle is having and the misfire on cylinder 3, that it might be the EGR valve? I didnt see that mentioned?

 
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EGR Valve generally has its own set of codes specifically for the EGR valve. If your worried about it, clean it.

I would systematically work your way down the list. You have already started.

Clean Throttle Body and sensors.
Check for vacuum leaks.
Replace plugs, wires, cap, rotor.
Get head gasket checked. This is one MANY omit and it is often the problem.
Get timing checked.
Get fuel injectors cleaned.

If it still does not idle nicely, you basically want to look into replacing the throttle body with one from ebay. They go for about 80 bucks if your lucky. Make sure it includes all the sensors and valves.

If it's still idling like crap then you want to do a compression test on the cylinders. I know your misfiring in number three but if your checking one you might as well check them all. If your losing compression you have bigger problems.

Good luck.

 
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i drive an 88 civic and mine used to idle low when i stopped and stall when i tried to drive away, turned out to be crap stuck in the pcv valve, don't know if that helps