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Bodie390
10-25-2005, 12:45 AM
At what boost pressure should a wastegate on a stock GN open. I've noticed that if I rev up to approx. 4000 rpm, the boost gauge (stock light bar on dash) will stay pegged and then car starts sputtering/backfiring like it's starving for fuel... Newbie with the GN here and I thought at first that I was having a fuel pump (starvation) problem but now I'm thinking maybe it's just making too much boost- i.e. wastegate not opening or too slow.. Anyone? Am I way off base??

kenmosher
10-25-2005, 09:59 AM
You shouldn't make boost just reving the engine ...

Even with the wastegate stuck closed, I wouldn't expect you to be able to make more than 1 psi of boost with no load on the engine.

Do you have a mechanical boost gauge? I think you need to verify that the stock gauge isn't screwed up somehow.

Ormand
10-25-2005, 10:11 AM
The stock boost gauge, and the stock tach, are pretty much just there to decorate the dash. With a Scanmaster, you can see the ACTUAL rpm, which may be a lot different from what the tach is saying. It will also let you see if you're getting knock, which can cause sputtering, as well as lots of expensive damage. As Ken says, you can't build boost just reving the engine, the engine has to be under load for the turbo do anything much. So, you pretty much have to driving, unless you have access to a dyno. You need to have a boost gauge, too. Casper's can recalibrate the stock gauges, but aftermarket is much easier to read.

Bodie390
10-26-2005, 05:52 PM
I guess I did not clarify that by "revving up" I was driving/loading the car. The more I observe this, the more it looks like it may be a fuel issue. Maybe regulator or pump. I found the fuel system test here and will go through that procedure first. I guess I will need some more accurate gauges and a scan tool. This is a great site with lots of information!!!
Thanks for your input.