Engine Roughness Bank 2

Hi everybody, my name is Alex and i got my Carrera 2 almost a year ago. Its from April 2000 and comes with the 3.4 liter engine. Right at the start it had problems running smooth. At start i changes engine mounts, transmission mount, spark plugs and spark coils. Nothing of that helped me to get rid of the rough idle. So i was taking my car to an independant Porsche specialist, who actually told me that the car is old and i should get used to that rough idle. The second "specialist" only checke the MAF and found nothing wrong about it. They had no further advice for me. After some time i got myself a reading device (Icarsoft POR V2.0) and it through some codes at me... P1128 / P1130 / 5525 and some others. I got rid of most of them, but P1128 and P1130 stayed somehow with me. Next step was to check the engine with a leak detector. I found a leak in the connection from the AOS to the intake bridge. Bought a selaing ring and everything seemed fine afterwards. But the engine still kept idling at 680 rpm with ~ 40 rpms going up and down. Next thing to check was the MAF, it runs with 1.06 V at ignition on. With the engine running and playing with the acclerator it never went above 2,4 V. A befriended mechanic told me that the MAF is broken as it should go up at least to 4 V. So I'll change that. Again i checked my reading device and it told me that bank 2 (Cylinder 4-5-6) had an engine roughness of 160 ms. Bank 1 was running fine with 0-2 ms. Next thing i disconnected were the oxygen sensors (i only have pre catalyst). And the engine really runs smoother than ever before!!! It idles at 680 rpm +- 7 rpm. But i still got that engine roughness on bank 2, which may be due to an air leak somewhere there. Or am i wrong about my suggestion? I already checked other threads in here, but haven't found anything close to my problem. Maybe someone has a good idea where to check now for possible failure?! I'm also planning to buy a Durametric System to read live data and continue my search. The Icarsoft device is not a help anymore. Best Regards Alex

It still may be a few things. When u get the durametric let us know what the variocam numbers r. Also the back cross over tube that has the resonance flap can have an air leak but its real hard to see. Have u changed plugs or coils yet?

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Air leak is very plausible. a (self made) smoke machine can be used to find the air leak or you could use brake cleaner and spray at places where gaskets and o-rings are used to seal joints. Do this whilst the engine is idling and listen for change in rpm. The last spot your sprayed brake cleaner at is where the (false) air is entering. Cracked oil filler tube is a possibility but also any of the vacuum hoses connected to the intake and anyrhing incorrectly seated that has air running through it. Durametric will give you the chance to view the lambda signal and see if it is running mostly lean and provide you with error codes to assist in finding the cause HtH

The vacuum reseviors for the cross over valve and PSE are not uncommon to crack, luckily they are cheap....

Maybe fuel related. Check fuel pressure at rail. Fuel filter ever been changed? Don't remember what year they got rid of the trunk mounted fuel filter. Fuel injectors. Smoke test, possible vacuum leak. Also might be worth performing a vehicle handover- basically disconnect the battery overnight to let the ECU re-learn mapping. These type of problems are the ones that can keep you up at night. --Aaron

Hi guys, yesterday i got my durametric and checked my Carrera with it. Plugs and coils are pretty new, changed in November 2022. I properly checked the car for air leaks. The only one i found was the one i showed above and after fixing no smoke appeared anywhere else. I also used brake cleaner and sprayed specific joints and connections. Nothing happened at all, the engine / rpm didn't change. And i sprayed it almost anywhere. According to your advices and this video ( You Tube ) i was checking the camshaft action. Once at idle and once at load, see photos above. It seems the camshaft on bank 2 isn't working/adjusting at all. Running the car with disconnected MAF and O2 sensors was this time pretty rough. Afterwards i installed the new MAF, but not much changed. The mass air flow was around 19-20 kg/h. The fuel trim Rkat and Fra was for both banks 0,0 and 0,99 with no change while revving the engine. While testing there were also no misfires in the cylinders 1 till 6. The ignition angle was in between 6 and 12 while at idle. The video above says 6 between 15 is ok. I can't tell if this is ok. I'm not a mechanic and just learning about that stuff, but sometimes i get lost with all the definitions and values. As i said, two porsche garages couldn't or would't help. Thats why i want to take into my own hands now. As a matter of fact the Durametric showed almost no engine roughness at bank 1 and 2. How come the Icarsoft device was showing it?! I'm know thing that my variocam is broken somehow and thats the reason why the idle is rough, or am i wrong? What should be checked next? Thanks for your help!!!

My 99 C2 idles at 675RPM and can also be a tad rough. Variocam issues will should deliver codes to the DME if they aren�t working properly.

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Are you sure about it? It seems like the Variocam on bank 2 isn't working / adpating at all Also the range for the camshaft deviation is +-6. I'm at -15.

I agree that it doesnt look lke bank 2 is moving. The acuators do fail on these motors so it may be your issue. It usually associated with a code but sometimes the early cars show funny or no p-codes.

I found that the actuators can sometimes get stuck due to dirt getting in them, liberal amount of brake cleaner while you test the actuator by supplying 12V on and off got mine unstuck again. Might be something to consider before buying new ones as these are expensive these days.

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Thats what I was told by a mechanic. If the solenoid fails, there�s a code for each bank. If there is no advancement, or too much advancement, if the cam position sensor is working, you should get a code. If the cam position sensor fails, you should get a code too. And nearly all of these failures should generate misfire codes. Maybe it�s possible that there are no codes. I know it�s possible to have cam deviation without codes, well past +\- 6 degrees. Just for your information, cam angle adjustment is up to 12.5 degrees of camshaft angle (25 degrees crankshaft) during Variocam activation. The Variocam activation starts at idle up to 1300 RPM (12.5 degrees of overlap) and stops at 1300 RPM (unless oil temp is 133C, then it�s 1480 RPM). No overlap happens again until 5120 RPM where the solenoids adjust 12.5 degree until redline. Both solenoids share the same transistor circuit on the DME 5.2.

First off :: What country are you in ? Take a picture of the sticker under the hood that gives all the info on the car ie .. order type, engie type, all options ect.. Cars built for the ROW market do not have a cam position sensor on bank 2 ...and if it is Not a ROW car it should set codes when not properly working unless someone has been monkeying around with the DME programming...