NM35 Factory Boost Gauge - dodgy readings

[myothercarsa2cv]

NM35 Factory Boost Gauge - dodgy readings

Hi all,

When I bought my 250t RS Four the boost gauge was showing some dodgy readings then packed in. After thinking it might be the well known dry joint issue, I dived in to the engine bay and discovered the vacuum hose had split and fallen off the plenum. Easy fix with some new hose and a zip tie, and all was well again.

Fast forward a couple of weeks and I developed a new problem, whereby the boost gauge would show 0 at idle, i.e. pulling no vacuum, building up to 1 under partial throttle. Then obviously it tops out so useless on boost.

This evening I tried the 'Scotty Fix' and wielded my soldering iron over the boost gauge sensor. I removed the old solder and renewed the joints on all three known failure points. I redid two I wasn't happy with, and confident that my soldering was now good I popped it back on the car and... it's still showing 0 at idle.

So either my engine pulls no vacuum, which I will test with my new mechanical gauge tomorrow (unlikely), or something is amiss electronically (likely). Has anyone come across a similar issue before? Could it be an issue with the gauge unit? Or should I try to find a replacement sensor? Are there any cheaper alternatives? These units are crazy expensive and difficult to get hold of.

Thanks in advance,

John

[scotty nm35]

Shouldn't be hard to find one, but it's likely just a leak.
R34 use the same sensor...

[myothercarsa2cv]

Stuck the Stack boost gauge on and it's pulling half a bar of vacuum at idle so definitely the sensor or gauge. Hopefully someone local can lend me a sensor to confirm it's that before I shell out.