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Before you go replacing any parts i would attend to the basics. Unless you are experiencing the previously mentioned "dashboard-in-your-face" fuel shut off (which i very much doubt you are) the reason for your lack of boost is likely something simple (and cheap). Don't throw away a bunch of money on "performance parts" before you know that the car is running properly in stock condition.
First, how much boost are you getting? If the gauge in the dash is only going to the mid-yellow then you likely have base boost. This usually means one of the built-in systems to limit boost is somehow being triggered when it's not supposed to be. Do a search on this board and you will find a ton of information. A quick way to tell if you are stuck at base boost is to to disconnect the plug at the APC solenoid and go for a drive. If boost is the same then you probably only have base boost.
If you are getting more boost than about halfway up the yellow range then you are probably not stuck at base boost however something may be preventing you from getting all the boost you could be getting. The four major culprits are:
1. Vacuum leaks: check those little black lines under the hood for cracks and breaks. Perhaps even replace all of them just to be sure they are not leaking boost (if you haven't done this already). Also check all the big tubes from the turbo to the inlet manifold. Look for loose hose clamps and torn rubber boots.
2. Spark Plugs and Wires: Spark plugs are a big one. Old, improperly gapped, or incorrect plugs can create a serious performance hit. Boost will be significantly reduced due to detonation. Old and cracked wires can have similar effects.
3. Ignition timing: Make sure you have your timing set to the stock setting (16' BTDC on your car if i recall correctly). If it is too far advanced you will experience detonation and boost will be reduced. Also check that the vacuum advance module on the distributor is working correctly (ie. that it holds vacuum). Again a lot of info on this site about testing the vac advance.
4. Base boost: Once you have got the three points above sorted out your boost may still be a bit low (ie. not into the red). You can now set your base boost by adjusting the waste-gate arm. It is useless to do this before all the other stuff is working properly. You will need a boost gauge to set this accurately. Do a search and your will get step by step instructions for this.
As for the advice from your Saabguy:
- Even a noisy pump is likely delivering more fuel at a higher pressure than the engine can use. Even if you wanted to build a Turbo 16V engine that would make 250 hp or more there would probably be absolutely no advantage in replacing the pump (or pre-pump).
- I kind of doubt you will notice much of a difference with the 3.0 bar fpr (over the 2.8). Again sort the basics before confusing the situation with upgrades
- The plastic bosch turbo bypass valve is kind of flimsy but if it is working correctly (ie. its diaphragm is not broken) there is no real performance problem with it. The only thing an atmospheric blow-off valve would produce is a bunch of noise
-APC valves can get gummed up but most problems can be solved by cleaning it out with some carb spray. That said, i have never personally seen a bad one(i know that others have though).
Anyway, good luck with all this- all part of the educational process.
posted by 216.113.195...
, Wed, 24 Jan 2007 21:06:23
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