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Stormy Breakdown (long) Posted by Arabiflora [Email]  (#1129) [Profile/Gallery]
(more from Arabiflora) on Wed, 2 May 2018 21:48:32
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’89 900S NA acquired spring, 2017, with probably 200k on the clock. Wednesday night I drove it from Madison, WI NE to Fon du Lac to help my son buy a used pickup. Just as it had on a recent 1800 mi round trip Madison to Atlanta, the drive up to Fondy was entirely without incident or worry. HOWEVER, I/we hit a band of severe thunderstorms on the way back home. In the midst of a torrential downpour my Virgini-Saab decided we had gone far enough, at least for the moment.
The incident began as a stumble at ~60 mph into the rainfall and very quickly lead to a complete stall. I coasted into the breakdown lane, set the e-brake and lit the emergency flashers. I tried a restart; no signs of life and so I called AAA. It was during the several interminable delays being on hold listening to really bad Muzak and the rains had passed that I again attempted restarts at about 5 minute intervals. At first there were no signs of life but then she seemed to want to run. I took that as a hopeful sign and reasoned that, perhaps, the residual engine heat had driven moisture from the ignition system and so I waited a bit longer and tried again. In the meantime, I called my/our Saabish friend RS to commiserate and to muse about possible root causes. It was then that I tried a restart again and it caught—until I tried to rev even a little bit; no go, she stalled, but it seemed a hopeful sign.
10 minutes later I tried again and she caught almost immediately. With patience and a light right foot, I could get rpms up to a steady and smooth 3k rpm. I let it drop (slowly) back to 900 and let her sit at smooth idle for 3-5 minutes. The rev-up from there was smoother still and still a bit stumbling but at least she continued to run. Encouraged, I screwed my courage to the sticking place, released the e-brake and began moving down the road again. I got back to a smooth-running 60 mph road speed, called-off the tow-truck and crossed my fingers.
I was able to drive the 45 miles back to my garage at my home without further incident and for that I am extremely grateful. She still stumbles a bit upon acceleration, a behavior I had not experienced in my ~one year of ownership and driving. Now I’m considering root causes and, as always, I turn to this board for suggestions. One possible clue that may help with a diagnosis: she occasionally exhibits an RPM “hunting” behavior during which, at a stop light or other idle, it runs-up slowly from 900 to 1.4 k rpms and then drops abruptly back to the 900 rpm idle point and the cycle (10 seconds total) starts anew. My mind leaps immediately, then, to a failing or fouled air mass meter (AMM). Alternatively (or in addition), I will note that I have not changed or even checked the plugs, wires, cap and rotor; perhaps those took on water during the deluge? Any other possibilities/likely culprits?
Although this episode ended rather happily, I’d prefer to go a very long time without repetition. I’d appreciate any suggestions re: other possibilities so post/reply away. I’ll be reading and replying to any questions and in the meantime will do the basics—plugs, wires, cap, rotor and maybe AMM if I happen to have a known-good one in my archives. As always, such intermittent problems are a bitch to definitively diagnose, test and remedy but those seem the minimal steps I can take to avoid a recurrence. At minimum, I guess I can do those basics and see if that eliminates the persisting acceleration stumble. I worry, though, about confirmation bias. Are there any other possibilities I should consider?
->Posting last edited on Wed, 2 May 2018 21:54:50.
, Wed, 2 May 2018 21:48:32 <-- Viewing This Message, Sat, 12 May 2018 00:58:19
1
, Wed, 2 May 2018 23:41:28
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