Help Troubleshooting Idle/Engine issue for 1997 Civic EX

[dkanter]

Hi - I'm a first time poster here, but long time reader.

I've got a 1997 Honda Civic EX (manual) and it's idling unevenly. Normally when the engine is running it always makes a very smooth noise.

However when I started the car last night, the engine was idling unevenly and the check engine light turned on. It wasn't making any particularly bad noises (no clunking), but it wasn't very smooth. When I was driving in first gear, it also seemed like the power wasn't getting fully delivered to the wheels, and it was quite difficult to go up hill to get a parking spot. The uneven noise continues until I get to a relatively high RPM (around 3K), or high speed (30mph in 3rd gear). I'm also wondering if the cold may be a culprit here, as it's been unusually cold for the last several days and when I noticed this problem it was at night and rather chilly out.

Does anyone have suggestions or ideas about this problem?

I found a couple of references on the web that suggested I might be able to check the engine light diagnostic codes myself, which would be great. I don't have the software or the jack to hook up, but this post suggested you can just use a paper clip (?):
http://www.askmehelpdesk.com/cars-trucks/2001-honda-civic-rough-idle-stalling-28503.html

Anyway - I appreciate any advice that you guys can share with me!

Thanks,

David

 

[RonJ]

Yes, the first step is to pull the CEL codes by jumping the service connector with a piece of wire or a paperclip. Click here.

 

['96 Civic man]

You might want to check the spark plug wires, my '96 civic ex was not idling right cuz one of the spark plug wire boots (the one that go's to the spark plug) was just sparking inside the cylinder (of the spark plug boot) so we replaced them and now it runs like new again!!

 

[fusion]

Yes, the first step is to pull the CEL codes by jumping the service connector with a piece of wire or a paperclip. Click here.

do that..tell us what the CEL is, then we can accurately diagnose the issue

sounds like a possible vaccuum leak.

 

[Docta2002]

Could also be a bad IACV but when you check the CEL codes (if any) you'll know better.

 

[RonJ]

In general, neither a vacuum leak nor a bad IACV would cause a loss of power while driving.

 

[brent_si™]

May have low compression which will cause rough idle and loss of power. My si idled weired when my valves need adjusted. After I adjusted them it ran perfect.

 

[fusion]

In general, neither a vacuum leak nor a bad IACV would cause a loss of power while driving.

actually a vacuum leak can cause loss of power. if the car has the incorrect air/fuel ratio, the fuel will not ignite properly and therefore create a loss in power. Same reason why alot of vehicles lose power when you turn the a/c on.

not saying a vacuum leak is the issue however it is probably something the OP would want to check into.

 

[RonJ]

actually a vacuum leak can cause loss of power. if the car has the incorrect air/fuel ratio, the fuel will not ignite properly and therefore create a loss in power.

In general, the amount of extra air bypassed into the IM by a vacuum leak is quite small compared to the amount of air that passes through the open TB while the engine is running. In addition, the O2 sensor detects the modestly lean air/fuel ratio, which the ECU quickly corrects. Therefore, an intake air/vacuum leak generally only presents as a high or hunting idle not as a problem while the engine is running.

Same reason why alot of vehicles lose power when you turn the a/c on.

This is an unrelated issue. The A/C causes a loss of power due to the increase load placed on the engine while it must turn the compressor and power the condenser fan.

 

[dkanter]

You might want to check the spark plug wires, my '96 civic ex was not idling right cuz one of the spark plug wire boots (the one that go's to the spark plug) was just sparking inside the cylinder (of the spark plug boot) so we replaced them and now it runs like new again!!

Alright, a little bit of blood and sweat and I am now somewhat familiar with my ECU.

The code I got was 72 - random misfire, cylinder 2. I checked the code 3x to make sure (and it's the only code that showed up).

That would be consistent with the 'uneven noise' that I hear at idle. Since it goes away at higher RPM, I'm wondering exactly what the root cause might be.

Thanks again for all the help from everyone.

David

 

[RonJ]

First clear the code from the ECU to make sure it repeats. If so, check whether the cylinder 2 spark plug has spark and whether the cylinder 2 injector has battery voltage. If both are fine, compression test the cylinders.

 

[dkanter]

First clear the code from the ECU to make sure it repeats. If so, check whether the cylinder 2 spark plug has spark and whether the cylinder 2 injector has battery voltage. If both are fine, compression test the cylinders.

Turns out you clear the ECU on '97 civics with the 15A fuse under the hood.

After I clear the ECU by removing the fuse, do I need to start the car so that the ECU can detect any other problems, or can I just check the ECU again?

I pulled the ECU fuse, waited about 2 minutes and re-inserted it. I checked the ECU again and got the same error code (72).

Thanks,

David

 

[RonJ]

I clear the ECU by using the 7.5A fuse, right?

Remove the 7.5A Back Up fuse under the hood for a few minutes.

After I clear the ECU by removing the fuse, do I need to start the car so that the ECU can detect any other problems, or can I just check the ECU again?

Take the car on a short drive.

I figure I might as well take a look at the spark plugs as well while I'm at it, since that seems like it might cause this problem.

Yes, inspect the spark plug and check for spark. Click here.

 

[dkanter]

Turned out it was the spark plugs - although I didn't have the tools, so I needed to get a mechanic to do the work for me!

Ron - thanks for all your help and guidance.

David

 

[NOFX]

Getting your own tools probably would have been cheaper than paying someone to do it. It'd definitely be cheaper in the long run.