Help!! #4 cylinder misfire 2000 Bonnie SE

[bluebeast00]

The service engine light has been off and on since I bought the car, so I took it to Advanced to have them run the computer to get the codes. One was the #4 cylinder had been misfiring and the other was the #2 O2 sensor had a malfunction. The kid told me that the misfire was causing the O2 sensor to have issues. As far as the misfire goes would I need to just replace the 1/4 coil? Or is there something else I need to replace to fix it? I had the light flash me the other day while going up hill and the car kicks a bit around 2500 to 3000 rpm. When I let of the gas I can accellerate and not have any problems for a bit. Any help is appreciated..Also if it is the coil, how do I replace it?

[Bing]

When was the last time plugs and wires were done on the car?

If the answer is "I don't know", replace the wires with Napa Belden's (lifetime warranty). Then get some NGK's or Autolite's (stay away from any platinum plug).

Yes, the back plugs can be a PITA to get at but it can be done.

This would be my first step. Please report back and let us know so that we can help you further.

[myfirstbonnie]

Also, in the future, it is best to get the actual code numbers and look them up here in our techinfo section when asking for help. There has been many cases where the "kid at Autozone" did not get the right info. Just tell them you want the code numbers.

[Archon]

I agree with all of the above. Another possibility is that your upper intake manifold, and/or lower intake manifold gasket could be starting to leak and causing the misfire. Do you know if they have been changed?

[bluebeast00]

As far as the plugs and wires they haven't been changed since I bought the car..it is in the works tho. I don't think the prior owners had changed them either. The gaskets I am not sure about either but will look into it. Thanks for all the quick responses!! I plan on doing the plugs this week.

[Bing]

Well, the possibilities probably pretty good the gaskets haven't been touched from the sounds of it. It's easy to check and see if you've got the updated aluminum ones though. Look in between the lower intake manifold (LIM) and the heads. If they are bright and shinny after scraping a little, they are the aluminum ones (good). If you see a black line there they are the plastic ones you'll want to change them as soon as you can along with the UIM. Another note is to get rid of the DEX if you haven't done so already.

[leatherneck]

I had a #6 misfire on mine and it was due to the wire falling down onto the rear exhaust manifold and getting hot and grounding out.. I temp fixed it to get it home and change the single wire as it was a new set. I was doing some work and forgot to reroute the #6 when done... So I have only myself to blame lol...

[Bing]

Yes, that is one to watch out for, but usually the wire ends up against the O2 sensor wire. This can create false/inaccuurate O2 sensor readings.

[jedwards83]

No real reason to avoid platinum plugs on a naturally aspirated 3800. A tad pricier but you'll get about twice the life out of a set. Do avoid Bosch plugs and their Platinum +2 and +4 gimmicks.

I agree with all of the above, important maintenance that needs to be done. I'd venture to guess that the plugs or wires are causing the misfire however.

[Bing]

Yes, that's true for a N/A 3800, but if mods are on the way I'd give it a second thought. Plus with the price that platinums run, you might as well just pay a little more for some iridiums. Platinums benefit is a longer service life, it's not necessarily the best conductor for spark plugs. Copper is a very good conductor, but its useful service life is not that long. Iridiums are kind of like having the best of both worlds. You get the longevity of platinums and good conductivity to.

[dayton.reed]

I had this problem, too. The exact same cylinder, too. The guys at the dealership played musical coils for a couple days, and eventually the problem magically went away. The only things they really did were: uninstall and reinstall coils a bunch, change the #4 plug and wire (didn't fix anything until several more rounds of musical coils), and burn a tank of gas revving it hard in their garage. That leads me to believe removing the coil and cleaning up the contacts could help, as well as possibly rerouting the plug wire just in case there is some kind of grounding out. If all else fails, replace the ignition control module.
I can't be sure any of this will work, but after a year of confusion and a week in the shop, this is what it took to make my misfire dissappear.

[bluebeast00]

I finally had the chance to replace the 1/4/5 plugs today. the car runs much better. I don't get the motor shakes everytime I accelerate up a hill. The plugs definitely needed to be replaced they were pretty bad. I'm not sure the last time they were done but I imagine it was quite some to
e ago. I plan on getting the 2/3/6 plugs done next week and the wires soon after. unfortunately its hard to do it all at once with little to no cash. The check engine light is still on tho this time I got the codes. P0140 a.d P0304. saying that now the O2 sensor OS now not functioning at all. well that'll be next on the. list I guess, if its not one thing its another

[Bing]

What plugs did you get?
So you did the front plugs, 1,3,5.
The back ones suck but just be persistent.

Do yourself a favor and get the Napa belden wires. They should run about 35$ maybe less, but you get a lifetime warranty with them.

As far as the O2 sensor is concerned replace it with either an AC Delco or a Denso sensor. Our cars do not like any of the other brands, especially Bosch.

[bluebeast00]

I ended up getting the AC Delco Rapidfire platinums. They seem to work pretty well. The back plugs were a bitch to get out tho! I took the Bonnie on its maiden voyage down the highway yesterday and had no problems. Still keep getting the check engine light tho. When I had it checked last week it was still on for the #2 O2 sensor saying that it's not working at all..

[myfirstbonnie]

That would be a bad O2 sensor behind the catalytic converter.