n75?

[balkranjit]

hi everyone.
got back from mechanic, and got a new steering rack, ouch i know.

Anyways we had the car running and talking and he noticed a ticking noise, which i thought was just one of the fuel injectors. He started examining and noticed it was the N75 valve. It was clicking approx twice a second. At idle. so he gave it a bit of gas while still in park and it went away. We went for a drive and he noticed that car being non-responsive at some points. Its auto so in second the turbo didn't kick in until over 3500rpm. and if was kind of pulsating. it wanted to go but wouldn't. but when he went hard throttle perfectly fine.

He said the N75 is on its way out thats why it won't make its mind up to start the turbo, and might be why its clicking at idle (by clicking he thinks its closing/opening or signaling unusually).

he said its either the valve going, or its the turbo going and the n75 valve compensating for the turbo which is why its clicking.

wondering if anyone here had similar experience or some knowledge of whats going on.

Its 1998 a4 1.8 tip. with giac chip, and drop in filter.

[discontained]

if your turbo is on its way out, I belive you will get a dentist drill noise, and/or no boost at all. Fluctuating boost is probabally caused by the N75 valve, i think, however I am not to shure on this, hopefully someone else will jump in as well..

[4BLKRNGS]

yeah it sounds like your n75 valve it controls when to open the wastegate and if the connection becomes loose it wont spool the turbo up. unplug the top hose on the n75 and take it for a short drive DO NOT GO WOT and see if the turbo spools right. if so then its your n75

[balkranjit]

Thanks for everybodies input. I did disconnect it and took for a drive and the surging feeling did stop. The ticking stopped right away as well.

So i took the car to the transmission guy to show him that the turbo/boost is not an issue with his rebuild its the actual tranny flaring at shift point.

Took him for a drive and the n75 unhooked the wire came loose and sat on the cat for a few moments and started to melt i saw smoke stopped the car and tried to save it. It was melted pretty good but we took it back to the transmission shop and melted/cutted it back to shape.

Now while they were fixing it, i recommended taking the purge valve wire and transplanting it for the n75 which i thoguht was more important. When i unhooked the wires i noticed that they were reversed.

So the n75 was getting purge valve signals from ecu and the purge valve was getting n75 signals. Once i swapped those everthing is back to normal. I kept getting the purge valve CEL even changed the bloody thing, but i guess it was just the old mechanic who messed it up. Anyways thought i post it up in case someone else gets the same bizzare situation.