Misfiring

[phewop118]

This morning I started my car and the engine felt bad, like it was misfiring. No SES light. I figure, I'll restart it, then it'll give me a light or run smooth. So after restarting it, SES is flashing, telling me for sure it was misfiring. So I shut it off, gave it a few minutes, and turned it back on. It was fine then, running smooth, no SES light. Could this be spark plugs (I have 80,000 miles on it, original plugs - 01, so 3.5L)? Or does it sound like I have other problems brewing. I was afraid to drive it, as I was worried it might start misfiring in the middle of my 70 mile morning drive and I want to minimize damage. Just as an afterthought, I wonder if the outside temperature has anything to do with it. This morning it was 25 degrees F, while for the last few weeks it's been well above freezing. Any thoughts?

[Jimmy Olsen]

Originally Posted by phewop118

This morning I started my car and the engine felt bad, like it was misfiring. No SES light. I figure, I'll restart it, then it'll give me a light or run smooth. So after restarting it, SES is flashing, telling me for sure it was misfiring. So I shut it off, gave it a few minutes, and turned it back on. It was fine then, running smooth, no SES light. Could this be spark plugs (I have 80,000 miles on it, original plugs - 01, so 3.5L)? Or does it sound like I have other problems brewing. I was afraid to drive it, as I was worried it might start misfiring in the middle of my 70 mile morning drive and I want to minimize damage. Just as an afterthought, I wonder if the outside temperature has anything to do with it. This morning it was 25 degrees F, while for the last few weeks it's been well above freezing. Any thoughts?

Have you added any gasoline anti-freeze recently.

[phewop118]

Gasoline antifreeze? Never thought of it. BUT I never had problems back in late January when it was -8 degrees F in the mornings.

[phewop118]

Well today I drove it on my short 25 mile Tuesday commute and no misfires. It did feel a little different, though maybe it was all in my head. The engine seemed louder and more intrusive and felt like it could misfire if I pushed it to hard. Yesterday afternoon I started it and it ran fine, but I revved it to about 3k rpms and it stuttered on its way back down. After a few seconds, it was smooth again. I'm wondering if I have bad gas? I have a brand new tank of gas - only a small portion (like 5%) is not from the other day when I got gas. In fact, I got gas 1 mile from my house and didn't even move the car until 2 days later when I started it and got the misfiring. Perhaps this is a mistake, but I'm going to my dealer later on today to have them check it with a Tech II. I have no SES light anymore, which I find wierd, cause I thought after an engine misfires, that the SES light would stay on until it was cleared with a Tech II or some sort of code reader. But I'll see after spending $35-$70 on diagnostics, but I won't get any work done on it today cause they don't have time to fit it in.

Basically what they'll probably say is that I need a tune up and to come back in and pay them to do it. I'll post back this afternoon with results.

[phewop118]

Wow I am amazed. I went to the dealer yesterday to have the problem diagnosed. They scanned it for codes and opened up the engine to look for problems and didn't charge me anything because they couldn't figure out why it was misfiring. The technician said there were misfires on cylinders 1,2,and 3, which is quite odd, and that they registed 50 miles before I brought it in, which is correct. He really couldn't figure out why, but said if it does it again, to try and bring it back in while it's misfiring. So I'll see. He also said that the spark plugs are in decent condition and they don't need replacing. Any thoughts?

[LittleHoov]

Well 1 and 3 are on the same coil, so that could be a possibility. You can test the coils to see if theyre good im sure, Im looking at my Chiltons right now and it has the coil test procedure for all the engines "except the 3.5" so it must have a different procedure not covered? Im sure the dealer knows how to test them, and you would think they would have done so.

[phewop118]

That was the first thing I mentioned to the technician. He said probably not, as cylinder 2 was in there also. If it were just 1 & 3, they probably wouldv'e tested the coil. Time will tell now. It's supposed to go back below freezing this weekend and I'll see how it runs. He also mentioned the possibility of having a stuck/frozen lifter. He said that is probably wasn't bad gas tho, as it'd continue to misfire and he said it wasn't the fuel injectors. Don't forget this, the dealer didn't charge to do this either, which I am amazed and will continue taking my car there for service.