DeWolf

Hi all. Changed my 1.0bar spring back to standard and overboost switch is cutting in. I had the switch grounded with the 1.0bar as it pushed a little past 1.0bar. I replaced the wastegate diaphragm when I fitted the 1.0bar as it had a small tear in it. It seems I can now hear the turbo whistling more pronounced than before. Have checked all vacuum lines etc. Ground the switch and away it goes, unground it and she cuts out. This is really annoying as I almost got done by a WRX this morning, lucky we have long 1st gears, didn't need 2nd, lol. Could it be a faulty relay. HELP

pete77930

if your overboost switch it factory it could be bad... mine went bad and I couldn't boost at all. installed an aftermarket adjustable overboost cutoff switch and set it to 1.3 bar( I run 1.2bar) and all my problems dissappeared.

911rudy

The first time I replaced the diaphram in the OEM WG I did not seat it into the groove inside the top part. I activated the overboost switch every time I went for top end boost. It seems like such a small thing but if air is slipping past the diaphram the WG will not operate properly and you will over boost. This is a good reason to have an after market boost gage installed so that you can see what is actually happening. That little thing on the tach is not for observation or determining actual boost pressure. If a real gage determines that you are actually over boosting, then you know where to begin your repair. Just replacing the boost cutout switch without knowing whether it is bad or not is stupid and you will have spent about half the price of a good boost gage. With a good gage you can ground the cutout switch and see if you are exceeding the BAR limit for your spring. Also, you could have WG bypass caused by high leakage around the stem of the piston in the WG. On my OEM the leakage was so bad that it hissed all of the time. I replaced it with a new aftermarket, (Not TIAL), WG and had no further problems with over boosting.
Good luck and I hope the outcome is positive for you. These things make us stronger or they make us sell the damn things!

nathanUK '81 930 G50

Where can we buy them ?

TIA

pete77930

I can't remember off the top of my head, I'll look through my reciepts and see if I can find it.

nathanUK '81 930 G50

That would be great as a lot of people need a part like that.

911rudy

Before you buy a new overboost cutout switch, just ground the one you have and that will tell you if it is bad or not. Take the single wire to the switch and bolt it to any bolt or screw near it and that will ground it. If your car runs ok, then you know that you have a bad cutout switch and you can replace it. There is a screw right next to the switch that will allow you to put the lead wire from the CO sw. to it and ground it without adding any wire or putting a jumper on the CO sw wire. I know because when I bought my '87 the CO sw was grounded ro it and all I did was loosen the screw and put it back on the CO sw.

DeWolf

Problem solved. Wastegate diaphragm had popped out of it's lip causing it to vent pressure.