Date: 22 Feb 2003 07:39:13 -0800 From: alancemornopsamo.com (Lance Morgan) Subject: Re: '91 Saab 900 2.1 non-turbo w/poor performance on acceleration
"Brian Dean" <BJDinNCnopsamsouth.net> wrote in message news:<wii5a.5391$Ye6.2696nopsam.atl2.webusenet.com>... > I have a 1991 Saab 900, 2.1 non-turbo with 140,000 miles in good repair. > > Beginning several weeks ago, it began to lurch when accelerating under load. > This lurching feels like momentary complete power cut-out by the engine ... > sudden in nature with immediate resolution... i.e., it seems to studder > rapidly while accelerating under load. If the clutch is pressed in it will > clear and rev freely. > > This occurs at start-up and continues, regardless of operating temperature. > > There are NO problem codes set by the on-board diagnostics. > > The vehicle has a new dist rotor, dist cap, and spark plugs. All are > correct factory specified components. > > The head gasket was replaced about 10,000 miles ago without incident and the > car ran faultlessly until just several weeks ago (probably less than 500 > miles with this problem). > > Any ideas would be appreciated... > Brian This type of problem can be difficult to diagnose, due to the number of possible causes, and the interaction between the (LH 2.4.2) fuel system and (EZK) ignition system. For DIY, you'll need to sequential trouble-shoot the two systems, using either a Bentley or Haynes service manual, on-line resources, a fuel-pressure gauge, a digital test meter, basic tools, and patience. I, too, would lean towards a fuel system problem, while not ruling out an ignition sys problem. A partial list of things to check: - fuel pump output - fuel pressure, including quick return of pressure after pinching line - air mass meter (AMM) - LH system and fuel pump relays (right-hand side kick area) - O2 sensor - vacuum leaks - ground points - general/physical wiring inspection & continuity and/or voltage drop testing - wiring and physical tightness of crank sensor behind crank pulley - ignition amplifier (sometimes called ignition module) - ignition coil - worn distributor Sometimes it's ultimately less costly and frustrating, and more expedient to take these type probs to a good saab mech - not only due to seasoned experience, but also being able to plug diagnostic equipment into the LH and/or EZK test harnesses [can help to pinpoint "ECU" (LH fuel control unit, right-hand side kick area) and/or EZK control unit (left front wheel area) failures, as well as other components], and other advanced tools like oscilloscopes, etc Lance 91 900S
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