[z06user]

(edit: also wanted to add that I did go over the misfire sticky thoroughly before posting this)

Just to give you all some prior knowledge about my car, I have been running Jb4 since October when I bought it at 62k miles (2008 335i Sedan, auto), car has 65k miles on it now, only other mod is the DCI and Jb4 only ever sees map 1 or 5 unless I use Sunoco 100 then I run map 2.

I have driven the car pretty hard the last few months and it has yet to give me any issues until 2 weeks ago when Cylinder 1 started misfiring. So I ordered a new set of Bosch plugs - ZGR6STE2. I have swapped the coil packs around and it seems to stay in the same cylinder. After putting the plugs in I no longer experience misfiring in cylinder 1 but now am getting misfiring in cylinder 2. I did have trouble with installation of the plug into cylinder 2, the stupid spark plug socket I got grips WAY too hard on the plug and I couldn't get the socket off the plug so I had to jiggle it furiously and then back it out and put it back in. There was a big build up of grime and crud down at the bottom near where the plug goes in, is it possible some of this could have fallen in and possibly clogged the injector?? I swapped the plug from cylinder 1 back to cylinder 2 and the coil packs again and cylinder 2 is the only one that still misfires. The misfire occurs under full load, idle is beautiful and after misfire occurs engine stutters until I stop and turn the car off and back on then it's fine until a full load situation.

Does anybody have any suggestions???

Just to recap, cylinder 1 initially misfiring, replaced plugs, cylinder 2 now misfires, swapped plugs and coil packs around and cylinder 2 keeps misfiring.

Also just in case I pulled a stupid the cylinder order is:

Front Bumper
1
2
3
4
5
6
Firewall

Right?

I guess I'm just kind of confused, I'm thinking it may be the injector in cylinder 2, but why was it only after the spark plug change that it started acting up?

Thanks in advance for any help that can be offered

[z06user]

I'm kind of thinking it's gonna be that injector, can anyone else concur?

[z06user]

Anybody have any good experiences with used injectors, kind of makes me nervous if they ship without the actual cap on the tip

[vasillalov]

Originally Posted by z06user

Anybody have any good experiences with used injectors, kind of makes me nervous if they ship without the actual cap on the tip

I had misfires on cyl 1. After replacing spark plugs and swapping coils, it turned out to be a bad injector. When I removed it, it had no visual clues that it had gone bad. There are too many things that can go wrong with an injector.

Not worth the trouble to mess with used ones! Get new ones!

[z06user]

You know what's weird, I think the misfire may have always been in Cylinder 2, it may not have moved, I have a code reader that is giving different results than the codes stored in the jb4, the code reader states it's cylinder 2. Another goof, I accidentally had all the plugs overtorqued by 5 ft lbs, not sure if that was responsible, but I corrected it. Seems to be running fine now, but it initially ran fine after I started swapping the plugs around, so I'm kind of hesitant to say that it fixed it. I'm guessing it's still the cylinder 2 injector.

[z06user]

I went back and torqued all the plugs properly this morning to 17lbs (edit: with a torque wrench), it seems that it's running fine now, my question to all of you: would overtorquing that plug cause that issue?

[Jeff@TopGearSolutions]

I would be careful over-torque anything but specifically sparkplugs. The metal is very soft and the threads can be easily ruined. It would be a costly mistake. You should invest in a torque wrench if you havn't already and torque them down to spec.

If plugs and coils do not fix the problem then its usually an injector problem.