Misfires on bank 2 cyl 4,5,6

[yeeha68]

1998 986 2.5.

Greetings to all.

Out of nowhere while driving last week, bank 2, cyl 4,5,6 started misfiring badly. As in really bad. My first instinct was that I was out of gas, but had a half tank, and found the codes to be only for bank2.

Some additional background which may be important to know is that the cam solenoid for bank 1 had been failing earlier and also needed to be replaced. I successfully replaced the solenoid this weekend (a job that sounds much worse then it is and will post a documented step by step shortly with tool creation details...but that’s another story) Anyway, after completion, bank1 seems happy, but I still have misfires in bank2.

Here are the current error codes via durametric software.

Fault Number:P0300

Fault Number:P0304

Fault Number:P0305

Fault Number:P1319

Fault Number:P1316

Fault Number:P1317

I understand what they mean, but have yet to solve the problem. I would suggest the solenoid in this bank also, but I im not getting the cam error as I did for bank 1 (P1340) and this idle is much, much rougher.

Here is what has been checked based on other posts I have found here:

Coils- tested within range between .3 and .7 ohms

Plugs- look good

MAF- recently replaced, but I dont think it would effect only one bank anyway.

Checked for air leaks

Fuel cap-checked

Oil cap-removes easily during operation and causes even rougher running off

AOS-clean, no cracks, no oil in throttle

J-tube-replaced O-rings, no cracks

No burning oil, no milkshake oil, coolant good.

Yep...Im out of ideas....here is some realtime data from durametric. I not sure if it makes any sense to me. I dont know what to look for but maybe someone else does. Should I be looking at a different set of data? It seems to me, one of the many selections in the software would pinpoint a red flag. Anyone with an idea?? Long shots are greatly appreciated at this point.

Thanks. :cheers:

A-Time

B-Rpm

C-Air mass

D-Hot film MAF

E-Ignition timing

F-Exhaust temperature after cat. converter

G-Oxygen sensing cylinders 1-3

H-Oxygen sensing cylinders 4-6

I-O2 sensor voltage ahead of cat. conv.

J-O2 sensor voltage ahead of cat. c. bank 2

AAAAAAAAAAA__BBBB__CCCCC_DDDD_EEE____FF___G___H__IIIII___JJJJ

19:15:04.3593750__1440___49.5___1.96___20.3___52___1___1__-0.01___0.23

19:15:05.9062500__1560___51_____2.02___23.____52___1___1__-0.01___0.22

19:15:07.3906250__1400___42.5___1.9____23.3___52___1___1__-0.01___0.21

19:15:08.8906250__1200___39.5___1.82___18.8___52___1___1__-0.01___0.2

19:15:10.3437500__1560___59.75__2.08___19.5___52___1___1__-0.01___0.19

19:15:11.8593750__2120___62.25__2.08___27.8___52___1___1___0______0.18

19:15:13.3593750__2080___62.5___2.09___27.8___52___1___1___0______0.17

19:15:14.8281250__2120___59.75__2.17___27.8___52___1___1___0______0.17

19:15:16.3125000__2480___56.75__2______27.8___52___1___1___0______0.16

19:15:17.8281250__2600___76_____2.39___27_____52___1___1___0.01___0.15

19:15:19.3281250__2720___106.75_2.6____22.5___52___1___1___0______0.14

19:15:20.8281250__3840___58.5___1.9____21_____52___1___1___0______0.14

19:15:22.3281250__2000___50.75__2.04___29.3___52___1___1___-0.02__0.13

19:15:23.8125000__1640___52_____2______23.3___52___1___1___-0.01__0.13

19:15:25.2812500__1560___48.25__2.02___24.8___52___1___1___0______0.11

19:15:26.8125000__1520___47_____1.96___24.8___52___1___1___0______0.11

19:15:28.3125000__1360___43.5___1.92___20.3___52___1___1___0______0.11

19:15:29.8125000__1160___40_____1.86___18.8___52___1___1___0______0.1

19:15:31.2968750__1040___33_____1.68___16.5___52___1___1___0______0.09

19:15:32.7812500___800___29_____1.66___15.8___52___1___1___0______0.09

19:15:37.5156250_____0___29_____1.66___15.8___52___1___1___0______0.09

[Loren]

The fact the misfires are only on bank 2 would seem to indicate that the problem is on that side.

I would swap a coil from cylinder 4 or 5 to the other bank (1, 2 or 3) and see if the problem follows the coil.

If not do the same with the spark plug.

[Cloudsurfer]

Could be the variocam solenoid going bad on that bank too. Supposedly, bad lifters can cause this too. I would try swapping plugs and coils from side to side in an effort to isolate first.

[yeeha68]

I swapped the coils and the plugs from one side to the other today. No change. Still get misfires on bank 2. It starts with cylinder 4, then 5, then eventually 6. Could this be a bad O2 sensor or burnt cat? Wouldn't I get an error code for these if it was?

My only other guess would be the timing. How would I set that or trouble shoot the issue? I have the durametric software but Im not sure what data to look for. Can anyone give me some pointers?

Edited October 17, 2009 by yeeha68

[Loren]

Then I would suspect a VarioCam problem.

See if there are any VarioCam tests or real time data - if so compare bank1 and bank 2.

If you can't do that with the Durametric then you will need a PST2 or PIWIS tester.

[yeeha68]

in the end it was a broken spring on valve #3

Details and pictures at www.nutrod.com