Date: Fri, 15 May 1998 10:33:38 -0500
From: ch <chobbsnopsamst.net>
Subject: Re: Need Help Figuring out 1987 900T Puzzling Behavior


Dbled, My first reaction to your problem is "FUEL". But then thinking about it. I realized that even if the fuel pump shut off the car would not just "turn off" and then on. Fuel and it's components are much slower to react to on / off situations. My next thought was Air, Maybe the Turbo APC system is acting goofy. I have seen a wastgate do something Extremely similar to what you describe. I would have the apc inspected. and even the turbo plumbing inspected for leaks. (even if that is not the problem it's a good idea anyway because that rubber is getting old.) but i bet the mechanics have looked at this. My last thought was electrical. and i bet this is an electrical issue . Mainly because mechanics are often stumped on electrical problems. ( they are REALLY tough to troubleshoot). At first the mechanic will look at the components that are closest to the engine. (thinking heat) except that ALL electrical components produce their own heat. even when far away from the engine.. My thinking is that your problems are related to SPARK. Either the distributor is messed up / or the coil / or the electrical components that control the spark . It has to be one of these. They are easy enough to diagnose. (usually with a multimiter and an hour of time. please email me on the progress of this one.. CH > dbled wrote: > > > > I just recently discovered this group and have been lurking here a week > > or so and thought I?d ask for some advice, opinions, or at least for > > some sympathy about an intermittent problem I?ve been having with my > > 1987 900T that?s been driving me and my mechanics crazy. > > When the car is cold, it always starts and runs OK. > > When I?m having the problem, the engine will momentarily cut-out as the > > engine starts to warm up (it starts about the time the temperature gauge > > starts to move towards operating temperature). This engine cut out only > > happens when there?s a constant load on the engine. It happens at any > > engine rpm and in any gear as long as there?s a constant load on the > > engine. The engine never cuts out when there?s a load on it (i.e. > > during acceleration, going up hills, etc.). it makes no difference > > whether the cruise control is on or off, the behavior is the same. This > > engine cut out continues as the engine reaches operating temperature. > > During this time, the engine isn?t constantly cutting out. It will run > > OK for a few minutes and then go into the cut out mode for a while and > > then run Ok for a while. On 3 or 4 occasions (over a couple of years > > time), after I?ve parked the car (with a warm engine), it won?t restart > > unless I let the car set until the engine cools to ambient and then it > > starts right up. It may or may not exhibit the cut out behavior after > > restarting > > The best description of engine cut out is a momentary (half-second or > > less) shut-off of the engine. It?s as though the ignition switch is > > quickly turned off and on. There?s no backfiring and the engine doesn?t > > stumble or act as if it?s running out of fuel; the engine seems to be > > either fully on (and running OK) or off. It may cut out once or twice > > and then run Ok for a while or it may cut out 5 or 6 times (resulting in > > a lot of jerking) before it settles down. > > What?s particularly aggravating is that this behavior is erratic. I > > might go months with the car running perfectly and then I?ll get a rash > > of this engine cut out behavior for a while (a few days to weeks) and > > then the car will run fine for until the next episode (anywhere from a > > few weeks to months). > > I?ve taken the car to several garages (including the Saab dealer) when I > > ?ve been having this problem and of course, they can never duplicate it > > and they can?t fix what ain?t broken. On several occasions they?ve kept > > the car for a few days trying to get it to misbehave. They swear they? > > ve done all the normal inspections, maintenance routines and replacement > > of fuel filters etc. I?ve also gone through the "bad" gas, water in the > > fuel, dirty injectors and other scenarios and still have the problem > > It strikes me that the problem is electrical (because of the nature of > > the engine cut outs) and its relation to engine temperature could point > > to some component sometimes failing when it gets warm. The intermittent > > nature of the problem is puzzling as is the fact that only constant load > > engine operation is affected. > > I?m sure there?s a clue or two here but we aren?t smart enough to figure > > out what they mean. Anybody out there have any thoughts? > > Otherwise I guess I?ll just keep truckin until something breaks.

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