pre-vanos intake manifold

[dinan540]

As you guys know,I have a 2001 540 and installed a pre-vanos intake manifold because of the difference in the diameter of the runners. The prevanos intake is the same as the dinan high performance intake manifold, except it is way less expensive. So I finished the install tonight along with new spark plugs, new valve cover gaskets, new valley pan, new ccv, new intake manifold gaskets and new rear and front gaskets for the intake manifold. I drained the coolant and refilled. Top off with quart of oil. Started her up and it idles so bad. After the car got some coolant/water into the block, it ran a little better. On initial startup, the car revs up to 5000 rpms and stays there for 3-5 seconds, then it drops down to 500 rpms. It sounds like it is back firing in the intake manifold or it is missfiring. Not sure. I went back and checked all of the sensors and bolts. Everything seems to be torqued down. I am at a loss.



I have a dinan TB, mass meter and air flow meter, stage 4 software and exhaust. I was planning to have the Dinan stage 5 software installed and tuned on the dyno. But it seems as if there is more to my issue than an air/fueul issue.



Any help would be appreciated.



Paul

[dinan540]

Found the vacuum leak. The prevanos intake manifold has a sensor toward the front on the passenger side. I inadvertantly removed it prior to placing it on the car thinking that I would place put my sensor in the prevanos intake. Well, my intake manifold doesn't have this sensor. Jusy an FYI if you do ths mod.

Paul

[denyo77]

good that you found it, have fun with your car

[RockyBalboaUK]

Hi

I am new to the forum and wondering how you got on with the pre-vanos inlet manifold. Were there any negative effects (low down torque decrease etc)?