Misfire w/o CEL?
 

Is it possible to have a misfire w/o triggering a CEL?

RE: Misfire w/o CEL?
 

Apparently the answer is yes. See picture taken from 96-98 Civic service manual.

[IMG]local://upfiles/25538/5ADD47ECD93B4543858FA76FE946884C.jpg[/IMG]

RE: Misfire w/o CEL?
 

Damn, RonJ, you're fast. I've got one more question...The cylinder #s are 4-3-2-1 from left to right, right?

RE: Misfire w/o CEL?
 

I don't know if it matters, but what year and model Civic do you have?

RE: Misfire w/o CEL?
 

98 HX. D16Y5

RE: Misfire w/o CEL?
 

Yes, when you are standing in front of the car.

The picture also may be helpful to you.

[IMG]local://upfiles/25538/2A1088DB692A4F7E8A3EB5F9B43EB233.jpg[/IMG]

RE: Misfire w/o CEL?
 

I'm assuming the problem I'm experiencing is misfiring. I'm hearing a rough idle/popping noise coming from the exhaust.

RE: Misfire w/o CEL?
 

Sounds misfire-like to me. Can you categorize the problem using the chart in the picture?



[IMG]local://upfiles/25538/5C238F8893DD455B8AC24ECBD8BD9137.jpg[/IMG]

RE: Misfire w/o CEL?
 

Hehe. I was just looking at the same chart trying to figure it out. Here's the deal: I converted my CVT (which uses a standard narrow-band primary O2 sensor) to A 5-speed (which uses a wideband primary O2 sensor). I just put in the wideband O2 sensor today (which got rid of the CEL I had for several months) and I replaced my ignition wires w/ NGK wires today too. Since I'm not getting a CEL, I'm assuming my new O2 sensor is functioning properly.

So, that means it's probably the ignition wires, right? Should I pull them one at a time while running and see if the idle changes?

RE: Misfire w/o CEL?
 

I think that's a good idea. Could you also verify by showing a lack of spark from the suspect wire?