Date: Sat, 25 Sep 1999 21:02:58 -0500 From: "JTML" <jetscapemnopsaml.msn.com> Subject: Misfiring 86 9000Twoes
Thanks to everyone who put down there thoughts on my problem (see bottom). I've gone through all the tests over the last month or so - haven't had too much time- and have eliminated just about everything but two parts that are in question. After putting a good $800 bucks into the car to get it in good shape, I don't want to dump a lot on replacing everything that is suspect. Update: it seems that spark is not consistently delivered to the plugs, and thus the idle problem is because the pistons are not firing continuously, and the billows black smoke is b/c of rich/unburned fuel. Using a timing gun shows the spark misses on multiple cylinders. I've checked the coil, voltage amplifier, connectors, HT (HV) leads, and grounds and all seem fine. At higher speeds the problem remains but is hidden under the higher rpms Turning off the AC causes the problem to get worse. I think this may be from losing the gas/idle boost associated with running the compressor, or possibly that there are electrical inputs/outputs that have gone faulty. Last clue, the idle is fine right as the car starts. Then within about 5-10seconds the problem starts. Theory: 1. Either the hall sensor is intermittent and is not sending the spark impulse the amplifier correctly. (From why I understand the Hall sensor is based on magnets so I'm not sure why this should be) 2. LH electronic control unit has gone bad and is flaky. (From what I understand here, the LH ECU controls the amount of time the injectors stay open. So what about the spark issue?) Questions: 1. which is more likely, and how to check it out without buying the wrong parts? 2. Is it possible that a worn distributor cap could cause this problem? The cap seems OK though there is some pitting. Any thoughts would be greatly appreciated. Thanks in advance. > I have a major headache with my 86 9KT. > It starts right up but does not idle correctly. Some time while driving it > feels as if there is a major draw on the engine- like a piston cutting out, > but i've checked the ignition wires and distrib. and they seem ok (maybe I'm > missing something) and I've changed the plugs. > Additionally when coming to a light the idle will dip and the car will > stall. If it doesn't stall it idles up and down 300-1k rpm and lets out a > hellof a lot of black smoke. I notice that when i put the ACC on econ (only > auto and econ on this model) the idleling problem gets worse. > > Without my saab 900 books, I can't figure out what to do, and need the car > to run until I can get my books to figure this out. > > Would appreciate any advice. Please be specific if possible. > > Thanks > > JT, > 85 900t (the first-born) > 86 9000t ( THE PROBLEM CHILD) > 93 9000cs (our baby!!)
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