Problems with boost

[mhelli1975]

Last fall I noticed that the car started acting funny when I would try to build boost. I was normally running around 18 to 20 lbs of boost with no problems. As the fall went on, if i tried to build 15 pounds of boost, the car would surge and build one more pound than back off and drop two pounds, this was all happening while I still had my foot in it. When I went to put the car away for the winter, I was lucky if I could build 5 lbs of boost. It would do the same thing it did at 15lbs. At this point in the game, I am getting ready to tackle the problem, but I don't just want to throw money at it and hope to find the problem. It seems to me the problem might be fuel related, becuase it feels like the fuel pressure isn't ramping up with the boost and it sputters and tries to build boost again. Any suggestions would be great.

Specs on the car:
87 GN , 52mm turbo, Turbonetics Racegate Wastegate, 50lb injectors, Reed 205/205 cam, stock converter, Stock Location Stretched Intercooler, bosch FP regulator, Hotwire kit for Fuel Pump

 

[Audie1]

For starters, check all vacuum lines. When in doubt replace the lines. Some may look fine, but when hot and under Boost a small unseen hole ballons and gets much bigger..........Always check the easy/obvious stuff first.......Also you can still build Boost even if you are loosing fuel pressure, it will just start running lean (which is bad).

 

[mhelli1975]

That does make sense, so it sounds like I should be thinking along the lines of a problem making/holding boost. I will check the lines when I get a chance. Thanks for your help.

 

[WSLN 6]

Wouldn't hurt to pop your downpipe off and see if your exhaust wheel is still there....I couldn't build boost (sounded like a fire engine lol) and turns out a cheap gasket took out all the blades on my exhaust wheel.

 

[unobetr]

easy way to find a leak, crank car, with the idle control on the tb, make the car idle around 2k, spray around the engine with ether, or starter fluid, (what have you), and if the car revs suddenly, you have a leak where you were spraying.

ck

 

[mhelli1975]

Thanks WSLN 6, at least I have somewhere to start. It definitely sounds like it is a boost related problem and not a fuel problem. Now to trace all of the boost/vacuum lines and see if anything looks cracked and pop the downpipe and see what the exhaust side of the turbo looks like. Let the fun begin.

 

[mhelli1975]

unobetr, thanks for the tip. I was wondering what the best way was to find leaky lines.

 

[unobetr]

np

 

[Audie1]

easy way to find a leak, crank car, with the idle control on the tb, make the car idle around 2k, spray around the engine with ether, or starter fluid, (what have you), and if the car revs suddenly, you have a leak where you were spraying.

ck

That does work great....unless it is a small crack that happens to get bigger when under Boost. Those are the hardest ones to find IMO.

 

[gnsrule]

Hows about getting back to the basics. How is the fuel filter ?

 

[mhelli1975]

Changed the fuel filter when I first started having problems back in late summer of '09.