If you have read my introduction, you already know I have a CEL with a few codes.

First, the ignition misfires (p0300, p0302, p0303, and p0305). I have changed the plugs, wires, cap, and rotor, and I'm still getting codes for an ignition misfire. Any clue what my next step may be to clear these codes?

Second, the o2 sensor response (p0133). I'm almost positive this o2 sensor was recently replaced by my mechanic before my inspection. Any clue as to why this o2 sensor circuit is having a slow response?

Third, the EVAP leak (p0442). I haven't looked into where this is coming from, hopefully it's just a small leak. However, if I do run into any problems I'll be sure to ask questions here

Thanks in advance for the help.

 

first: go to your local oreillys or other auto place, and use their obd2 reader if yours has it (would be right in front of the shifter under the coin collector) and clear the codes

second: pull the O2's and clean them to see if it helps, and if you have to replaced only go OEM (non splice O2s)

Third : Check your evap lines one comes off the intake over to the radiator then works its way down and under. Charcoal canister is below the battery, check your lines running under the car on the passenger side, specially the plastic ones, and also take a peek behind the fuel filter, and check the rubber to plastic lines running from a small canister looking thing which runs up to the top of the gas tank.

 

I have my own obd2 scanner and have cleared the codes multiple times. The CEL has come back a day or two after each clear. I'm hoping after the storm we're getting over the next couple of days, the sun will be out and it will warm up a bit. I can then possibly check the o2's and evap lines. I know when the first o2 sensor was replaced, my mechanic used an OEM fitted sensor. After wasting money on a universal o2 sensor for my Eclipse, I have learned my lesson to never skimp out on my o2's after that one has failed a few months into use.

Thanks for the very helpful information, especially on the evap lines Do you know anything else that could be done to get rid of the misfires? My mechanic said he checked it out and said he had no clue what could be causing the car to misfire. He said that he does not hear a misfire when th car starts up and that it runs great.

 

possibly test the output on the ignition coil. If thats low, it could be responsible for the misfires.

 

Will do.

 

Have you checked the compression and fuel pressure? The ignition system is not the only cause of misfires... How does the car run?

I would fix the misfires before worrying about the O2 sensor code; fixing the misfire issue may resolve the sensor issue too. Unless of course the O2 sensor is so bad it's causing the misfire, but it would have to be quite bad to do that; if you suspect that you could unplug the O2 sensor and run it open-loop; see if the misfire codes stay clear...

 

I have yet to check the compression and fuel pressure. The car doesn't run bad, but when idle there is a significant amount of vibration. This started well after I knew of the misfires though.

I cleared the codes again last night and the CEL came back on today. I did a scan and only two codes popped up. One of which I can't remember if it was p0130 or p0133, which has to do with sensor 1. The other was p0140, o2 sensor circuit no activity detected (bank 1; sensor 2).

With the amount of driving I'll be doing tomorrow to school and back, the CEL should be back on. From there I can do another scan to see what pops up.

 

I finally ordered and installed my new coil pack, two months later... I let the car run for about ten minutes. The CEL did not go away, so I ran a scan before clearing the CEL and came up with p0133, p0300, and p0303. I assume a compression test and o2 sensor cleaning should be next?

 

Are you sure the wires are installed correctly? What year and model is the car?

 

It's a '96 base model. I'm almost positive the wires are installed correctly.

Looking at the spark plugs with the cover off, 1 is on the far left and 5 is on the far right. As for the distributor cap, 3 is at the top. Going clockwise after 3, it's 5, 4, 2, and 1.

 

Just to cover the basics: have you checked the vacuum lines? is anything hissing? While you check fuel pressure (like gdog stated), same gauge can be used for checking vacuum. Secondly, do a visual check / light-yank check of electrical connectors, wires and ground straps. Are the battery connections tight? Sorry if you covered this, but most times is the simple things.

 

Let us know what happens after you check fuel pressure. I do know these cars will pop codes, especially misfires when starved for fuel. The only thing that gets me is that the fuel problem is usually a shut down situation instead of a running irratic problem.

Did you also replace the fuel filter?

 

Depending on when I get a tester, I'll let you know.

Yes I did replace the fuel filter.

 

these codes can be from a bad EGR valve , did you have the engine smoke tested? thats when they run smoke in your vacuum line and the smoke will show you every leak in the entire vehicle ,even in your injectors

 

I have not. When I had one of my strut mounts replaced I had my mechanic take a look into the misfires. I'm not sure if he actually took a look into them, but he said he can't see anything wrong and that the car is running good.

I'm going to see if I can find a fuel/vacuum pressure tester around here to have for Monday when I do some work.

 

I just want to give a little update...

I picked up a vacuum/fuel tester today. I quickly tested the vacuum before heading into Boston. Cold it was at 15 and once the engine warmed up, the vacuum was about 13. I'm unaware of what the vacuum should be at for an 850. The tester can also test the fuel pump, but I just installed a brand new one.

As far as testing the fuel pressure, I heard that instead of dropping $30-50 on a fuel pressure tester a tire gauge will work? The tire gauge may not be precise, but it will give you an approximate idea of what it is. Is this true?

 

Forget the careless tire gauge idea. I'll just pick up the right tool to do the job tomorrow. I'll just look around for an inexpensive one.

 

I tested the fuel pressure today, it's at 45-47psi when the engine is warm.

 

Vacuum and fuel pressure are good. Slight Yank-test of the electrical connections? Battery terminal?

I am having a similar misfire problem myself. Started it twice this morning and it sounded not good -- like a vacuum line was pulled out. I didn't have time to check it out. Will do later on... I do have a slow response O2 sensor myself, which hasn't thrown a code yet. In my case, I suspect an electrical problem, since the engine bay got sprayed with antifreeze and hot oil... LOL

 

This is how to interpret vacuum readings.... How to Use and Interpret a Vacuum Gauge