intermittent miss on 05 sable fun

[CJ]

So, car started getting an intermittent miss about a month ago, I noticed it, but it wasn't too bad. Then I started to notice what felt like the transmission slipping in the 3-4 shift. When it would shift, I'd get a pretty healthy bump which really felt like tranmission, and given the AX4N/S isn't exactly a great transmission, I figured we were going down that road. I had done a trans service about 30k previous, checked the fluid, smelled fine, didn't seem like an issue. Initially, at idle it would miss maybe once every few seconds, very minimal. As time went on, it started to get more frequent, and a much bigger bump. I then started to get pretty bad hesitation off idle and noticed most of the missing was at low RPM under a load. So I surmised it wasn't the tranny slipping on the 3-4 shift, it was a miss at low rpm loads. So, since it's at 90k I decided I'd do a tune up. I did plugs, belt, fuel filter, and checked the duratec for any of the typical problems, it looked fine. Once I took it out I heard a very small exhaust leak and immediately knew what it was, I had loosened the bolts on the EGR pipe and didn't tighten them. I tightened those up and it threw a code on the next drive. I checked codes and I got a P0300, P0306, and P1406. One of the hose nipples broke off the DPFE (typical) so that will have to be replaced, that will solve P1406. The other codes I expected, random misfire on start, and cylinder 6 misfire. Thank god it wasn't cylinder 1, 2, or 3. I checked the plug, looked fine, so I replaced the coil, presuming it was ignition related. Well, it wasn't, because that didn't change shit. So, I'm going to guess what I have is a bad injector on cylinder 6. I'm not seeing any pressure bleed down over time. I'm guessing it's the injector though, I can't think of any other causes. I plan on swapping the plug and coil over the cylinder 4 and seeing if the code changes, if not then I can only presume it's the injector.

Does my reasoning make sense there?

[Baron Von Crowder]

I have one with the same issue. Haven't solved it yet, but I'll update hopefully tomorrow with what we find.

[CJ]

well, DPFE will overcompensate with no vacuum and cause a lean condition, that might cause a misfire, I'll let you know.

[butt86]

3.0ohv not the dohc? If I remember correctly these had issues with the valves on those motors. Hopefully not that but something to look into.

[CJ]

duratec - dohc.

[JC316]

3.0ohv not the dohc? If I remember correctly these had issues with the valves on those motors. Hopefully not that but something to look into.

My first thought as well, but he said that it's a duratec, which is the DOHC. there is a possibility that the ECM is getting confused about which cylinder is misfiring. Ran into that with a BMW, was saying cylinder 6, but it was actually cylinder 3 giving the issue.

I don't know if the taurus has the same issue, but the mazda 6 has an issue where the cat converters break down and get sucked back into the engine through the EGR tube. Can cause issues like this.

[CJ]

My first thought as well, but he said that it's a duratec, which is the DOHC. there is a possibility that the ECM is getting confused about which cylinder is misfiring. Ran into that with a BMW, was saying cylinder 6, but it was actually cylinder 3 giving the issue.

I don't know if the taurus has the same issue, but the mazda 6 has an issue where the cat converters break down and get sucked back into the engine through the EGR tube. Can cause issues like this.

yes they suffer from cat issues as well. However, usually those cars experience a power loss throughout the band, whereas mine is only missing on low rev's, but in the high range it runs just fine, and is not down on power at all.