I have a odd boost problem. I had wrote in earlier about lowering fuel pressure to 25 psi and still being rich. That turned out being the wrong chip (stock chip blue top injectors). My MAF also was only going to 168gps. That is also fixed. Got a new one from GSCA club for 156.00. Now what is happening is when I punch the pedal to the floor. The boost goes to all most 20psi then drops to 14psi and slowly builds to 16psi. My O2 is .92 at 41psi fuel pressure. My BLM is 112 to 101. Could I have a exhaust leek. I can't here one. Please help this is getting frustdrating.
Both your O2 (I'm assuming that's at WOT) and BLM numbers show you to still be running rich. Is the FP being checked with the hose to the regulator disconnected, as it should be?
The boost fluctuation may be due to an inadequate wastegate hole size, or a misaligned wastegate 'puck'. I'm assuming you still have the stock elbow/downpipe setup. Look at http://www.gnttype.org/techarea/turbo/turboport.html for some discussion about porting the wastegate hole in the turbine housing.
Thanks Scott. I have a ported elbo with the larger puck and a ATR down pipe. I'll try them next. Then see if I'm still rich and tune from there.
Ken
Might have found a problem with my exhaust. I did the port work to wastegate hole on the exh. housing for the larger wastegate puck. When I took it apart it looked like the flange was leaking from the exh. manifold to the turbo. When I put it back together it is leaking. Not enough to hear but you can feel exhaust coming out. Could this cause my boost fluctuations and does anyone make a gasket for this flange.
Ken Williams
87GN
Are you talking about the 3 bolt flange right at the turbine inlet? Yes, that could cause fluctuations. ATR makes a nice copper gasket for this junction.