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Hi all
I am still continuing to troubleshoot some issues with my recently acquired 92 900 turbo and thanks to many of your responses and advice and of course the Bentley manual was able to diagnose the failed cruise control and base boost problem. As it turned out several of problems were overlapping ie leaking pressure switch on the clutch pedal solved the vacuum / mechanical aspect of the cruise and the base boost. In both cases the base boost and non functioning cruise was do to failed electronics ie APC box and the ECU for the cruise. Electrical diagnosis is not one of my strengths in SAAB repair but great advice and trend failures helped Thanks again!
At present I am only getting mid to 3/4 yellow boost which translates to about 8 to 9 psi. I have replaced all vacuum lines and checked by removal of the turbo plumbing as well as rubber grommets in the intake system. Basically I feel the intake plumbing is leak free and adjusted the base boost according to Bentley. When the APC system was elimiated by pinching off the bypass line from the APC solenoid to waste gate accuator, boost went to about 12 psi (test vacuum gage) 1/4 red (panel boost gauge) so the turbo appears to function properly.( slight pinging detected at 1/4 red)
When accelerating wot the engine boosts to its max level (1/2 to 3/4 yellow depending on outside air temp and using premium fuel 91 octane (california)) Knock sensor appears to work as it should( Reaching max boost level at a given oat and engine at a normal temp boost abruptly backs off about a needle width.
I checked the timing and it is 16btdc. the vacuum module on the distributor holds vacuum and pressure when tested with a mity vac.
and all new ignition parts ie NGK BCP 7ES and Bosch cap/rotor and of course new Bougicords plug wires!
Sorry for all the back ground info but as you might have guessed I am at loss for the lack of boost to at least to top of yellow! At present I am thinking that lack of boost maybe fuel related. I have not tested the stock pressure regulator and the fuel pump seems to function normally.
The engine idles smoothly and dosnt cut out under load indicating possible fuel starvation. After a fully warmed up test run I removed the plugs to inspect color and found all electrodes where whitish in color and the threaded portion surrounding the electrodes were slightly brownish in color. Is this normal for a turbo since I was testing the boost limits where the APC backed off the boost. My normally asperated 900 plugs are always a nice brown color! Maybe there is a non obvious air leak else where.
Other than slightly lower than stock max boost the car seems to run really well and gets good mileage . Considering that this is a completely stock turbo and 91 octane is the best California offers is this it for boost unless performance mods follow? Any thoughts would be greatly appeciated Tia JK
posted by 69.20.146...
, Fri, 28 Apr 2006 13:35:07
, Fri, 28 Apr 2006 13:09:07, Sat, 29 Apr 2006 14:56:54, Fri, 28 Apr 2006 15:42:33
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