Another boost issue

[Matti85]

Started the car yesterday for the first time this year, have been offroad for 8 monts now, started fine and all but when i was going to warm up the engine a bit by reving it slow, i could not hear the turbos or the bov (reved to 4k as most before i shut down) now today i got a boostgauge fitted that seems to work fine it starts at 0 bar but when i give some gas to rev it the needle goes down to - side insted of the + side ?

 

Although i have fitted an new SMIC, did that 2 months ago, ive bought some stuff to check for any leeks through the IC piping tomorrow but thought i asked her as well for more ideas.

[Steviekid]

it starts at 0 bar but when i give some gas to rev it the needle goes down to - side insted of the + side ?

 

It should be -ve at idle and up the rev range until the first turbo comes on. Does it not go positive at all?

[ardasaliah]

you wont make no boost by reving the car. hence not hearing the bov. Turbos produced boost when there is load on the engine. Its imposible to produce boost by reving the car. you need to drive the car

[Steviekid]

you wont make no boost by reving the car. hence not hearing the bov.

 

Of course you will. Turbos make boost when there's enough exhaust gas going through them to spin them up. I can easily get +ve pressure and the BOV going by reving the car.

[Matti85]

Yeah before i took out the cracked SMIC i could well hear the trubos spool while standing still and reving and later the Bov releases the pressure out, now when i fitter the Miami GT new and and with no leeks at all (tested today) i cant not hear the turbo or bov at all. Can not teast the car on the road anytime soon but will do ofcourse, but if the trubos are dead im affraid to take it out and floor it, will surelly do more damage.

 

The boost gauge i fitted never goes to the positive side, the needles just goes down - when i rev, almost as if ive fitted it upsidedown. But it is correct fitted.

[terribleturner]

Have you put fresh petrol in?? After 8 months it may have gone a bit stale.

[Matti85]

Thought out another question, the boost gauge read negetive, but it is moving, the minus side got counts from 1-6 or something, and when i rev it it goes down to 4, does not that mean that it is pressure there, i mean needle should not move if both turbos were dead, and here it does move even thought it is the wrong way. Pressure is caused from the trubos right....

 

Just something i thought about

[Steviekid]

Pressure is caused from the trubos right....

 

The negative pressue is caused by the pistons sucking air in creating a vacuum, then as the turbos come on this should reach 0 then +ve pressure. Was the car running ok before it went off the road? I'd be amazed if your turbo's had died when the car was sitting in a garage.

[Graham S]

Have you plumbed the boost gauge in properly, possibility you've left a pipe off somewhere? Where is it plumbed in?

[ardasaliah]

Of course you will. Turbos make boost when there's enough exhaust gas going through them to spin them up. I can easily get +ve pressure and the BOV going by reving the car.

 

 

You sure. I know exhaust gases pass through when you rev but no enough to make anything more then 0.1bar. Load is needed. The bov sound is boost but nothing much. I can't get my car to boost by reving it. Only in gear and yes turbos are fine.

[Matti85]

Steve ive fitted the gauge according to this guide, dont think there are any loose hoses connected to it, i made sure of it.

http://www.mkivsupra.net/vbb/showthread.php?t=67657&highlight=boost+gauge+fitting

 

The car had a major boost leak before i took it of the road, the SMIC had a big crack, car drove like an NA. But atleast i heard the turbos and bov back then.

 

Only thing ive done was fitt a new Miami GT one and put on a boostgauge. Cant hear the turbos or bov anymore and the gauge reads negetive, but atleast ive not taken it out on the road to test i properlly.