05 Passat surging

[twballenger]

Just rebuilt this engine, new balance shaft module, crankshaft, colt second stage cam, & turbo. The engine started right up and idle's fine, but upon acceleration the engine surge's to higher rpm and then back down to near idle speed and this will continue while holding the accelerator down, sudden increase in rpm then back down to idle. After letting up on the pedel it returns to idle speed and runs smooth. Also the emissons and workshop1 came on in the dash, what ever that means. This has been a big 5/5 job, any thoughts would be helpful.

[chittychittybangbang]

Emissions workshop is usually a major code, suggests some wires or sensors not right. A quick code scan will let you know.

If it's running, doesn't sound like a mechanical problem. Since engine was just redone, some suspect areas could be camshaft ring sensor or camshaft sensor.

[twballenger]

Originally Posted by chittychittybangbang

Emissions workshop is usually a major code, suggests some wires or sensors not right. A quick code scan will let you know.

If it's running, doesn't sound like a mechanical problem. Since engine was just redone, some suspect areas could be camshaft ring sensor or camshaft sensor.

Unable to rent local code scanner for vw diesel, sooo I'm taking it to the shop for a diagnostic, will post the findings, thanks for the help.

[twballenger]

Need a little help please solving this surging problem. BHW engine runs smooth to 1100 rpm then surging occurs past that while pressing on the accelorator. This engine has been completely overhauled, it is not in the timing, computer, and the cam sensor has been replaced. Don't know where to look at this point, could I have done something during the reassembly, a plug in the wiring harness swapped around, fuel pump timing, I'm open for suggestions, appreciate any help.

[chittychittybangbang]

Here's a guess, triple check vnt actuator movement:start-stop "of vac and the stop screw position. I fixed some minor surging by adjusting the stop screw, perhaps there's something wrong with yours,see FAQ for TSB and some more info and vids.

Your description sounds like major surging, also what were the codes, you never posted your findings.

[twballenger]

Speed sensor code P0321 indicated an open circuit, replaced sensor no change, dropped oil pan found bent sensor wheel, apparently happened when the transmission was installed. Straightened the bent place and now the engine runs fine. Some things you learn the hard way.