Hey guys just hoping to pick someones brain who may have had similar issues. I have 03 b6 1.8t CVT chipped (upsolute stage 1) and darintake'd about month ago. One week ago I was out at my parents and there is a 11.8 mile stretch of two lane highway out in the middle of nowhere (literally the nearest grocery store is 50+ miles away) its flat as a slate pool table top, straight and beautiful. Its literally a dream come true for a guy who wants to run his car flat out. My problem: From a start at wot the car's power is great as the rpm's climb the power comes on great until about 5200-5500 revs, at that point there is an immediate and quite noticeable drop in power at which point the revs will drop as it loses power then at <5000 rpm's the boost comes back it throttles back up to 5200+ and the boost is gone again. If i hold the pedal at wot the car starts a series of this boost no boost boost no boost until i let off the throttle. All the while accelerating (SLOWWWWWLY)like there is no turbo. This condition occurs when the car is first run as well as hours of running. If I do not put pedal to wot and keep revs as best i can in the mid 4000 range the power is solid. I'm leaning towards factory diverter valve possibly not being able to maintain the pressure. I'm going now to pressure test (DIY STYLE) the intake system but have only a quality bicycle hand operated air pump and don't know if it is going to work. While I'm out there anyone with similar issues that could point me in the direction of more troubleshooting ideas or fixes? Any suggestions on a diverter valve. I guess with the chip I'm supposed to be around 18 psi i thought factory dv should be able to handle it.

 

After the drop in boost, does it come back? Does it happen all the time? Usually boost leaks are between any rpms ranges (in boost). There is a big chance that it is your DV, that's why they recommend to get at least a 710n valve.

 

yes after engine speed is 5300 rpms boost disappears and reappears at a rate of about 2-3 seconds with boost 2-3 seconds without. This is happening the whole time rpms are above 5000 and throttle is wide open. wot the engine vascillates between power and no power as if someone has a switch that they flip at will in cycles of off again on again all while holding pedal to floor. Takes about 10 seconds to go from 80 mph to 90 mph.

 

Do u have a CEL, how is your car running at IDLE?

 

I'm going to say that the little K03 turbo can't produce expected boost past 5200 RPMS and that's why it dies off and feels like there is no boost... because there isn't.

 

Thanks guys for responding I really appreciate it. Audiprotein, car runs fine at idle and no cels pulled the dv and tested(compressed the valve placed thumb over small fitting and doesn't maintain any suction whatsoever when release the valve) so I think it is bad. However I did "clean" it with some wd40 and excercized the mechanism and I now cannot notice any variations in the boost well into the upper 5k rev range. Although I still don't feel that the car pulls like it should. I may be being neurotic but I am still going to replace the dv with the 710n and possibly replace the n75 valve...J or stock version....any suggestions?

 

There is some truth, but ko3 lasts a bit longer. Anyway, not in his case, cause he said it takes him 10 seconds from 80mph to 90mph.
Try replacing the DV first, and then if doesnt work, try the n75 valve.

 

Did the 710N it runs out great thanks. Now I want more...

 

More boost?

 

Yeah, more boost, more power, more acceleration better handling...every little improvement just makes me want to get better and go bigger even though I realize at a certain point it would reduce the functionality of the car. Kicking myself for buying a CVT should have been more patient...