Over boast questions - revisited

[s_morrison57]

Hi
I posted a couple of weeks ago on a suspected over boost problem, got some good responses back , most were over my head. Since then I've been doing some reading from the manual and have driven the car a lot and have a better description of what I see.
I got the 87 930 last year but with work and wheather I put only about 500 m on it till just recently, also when I got the car I had to change the relay(?) under the drivers seat close to the door sill, it is supposed to shut off the fuel pump(s)(?) on over boast or on over rev. I know it shuts the fuel off @7200 and I'm assuming that the boost shut off would be at 1.1 - 1.2 bar but I hear nothing from what I would consider the waste gate popping off, does it make a noise on your car? Does your acceleration slow, cause this thing just keeps pulling.
When I punch it in 1st, 2nd or 3rd the boost gauge goes up quite fast and by 5000 RPM or so the gauge is pinned past 1 bar, if I lift and get back into it the boast is at about .4 and climing but doesn't go past .8 before I shift at my redline of 6400 RPM.
I'm suspecting that the boost gauge is not operating properly or that when the turbo was changed before I got it that the spring was also changed to a higher boost, I have the bill but no details on the spring or if a stock or bigger turbo was put on , that was @41K and the car has 60K on it now . If you assume the new relay is working then the gauge is not reading accuratly , the car does not shut down on the over boost . How does your car and gauge react?
I'm a little freaked at hurting the engine as any repairs are just not in the budget now but I do love punching it.
Thanks for any help or insights.
Finn

[A930Rocket]

The factory gauge is nortoriously (sp?) bad. Get a NHS gauge that fits in place of your cock or a gauge you can use temporarily use to measure boost.

Second, the overboost switch is on the stock intercooler with a white wire going to it. It shoud kick in at 1.2-1.4 bar and when it does, you'll know it as the car just dies after being on boost. Be prepared to eat the steering wheel.

[mark houghton]

Originally Posted by A930Rocket

The factory gauge is nortoriously (sp?) bad. Get a NHS gauge that fits in place of your cock or a gauge you can use temporarily use to measure boost.

Second, the overboost switch is on the stock intercooler with a white wire going to it. It shoud kick in at 1.2-1.4 bar and when it does, you'll know it as the car just dies after being on boost. Be prepared to eat the steering wheel.

i.e., the FITD syndrome (face it the dash). Oh, and there's not need to be profane about boost gauges, though they can be suspect.

So Finn, did you send pictures earlier? Can't help without pictures, you know.

When your wastegate opens, you will still continue to accelerate like an ape after having forced sex. All the WG is doing is venting enough exhaust away from the turbo to keep the output at .8 bar (or whatever spring you have in there). The exhuast note usually gets measureably louder, unless you have the stock little WG dump pipe muffler still on there.

Do check into the accuracy of your gauge. If you haven't shut down on overboost, then I suspect you're not over boosting. Usually it's just the gauge sender that's bad, and they're pretty spendy little buggers. Get a good aftermarket gauge...you can hook it into the brake booster vacuum line behind the dash. Or go electronic like the one I have, but be prepared to crawly around under the car trying to route the wires up to the cabin.