Saab - Car "jumps/shakes" on uphill in 4th and 5th gear & often takes multiple turns of key to start.

Mike Howard

Asked by Jan 15, 2014 at 08:17 AM about the 1999 Saab 9-5 4 Dr 2.3t Turbo Sedan

Question type: Maintenance & Repair

The issues do not seem related but
they both started around the same
time so figured I would ask together.

The "jump/shake" on uphill
happening more and more frequently
now. When it happens it just sputters
and keeps going, no engine rev or
anything like that.

For the issue turning the car
on...there is more than enough
power and the battery is oldish but in
good shape (and I tested a brand
new battery and same problem).
Often takes 5-10 seconds of solid
cranking, and often 2-3 cranks,
before engine rolls over (always rolls
over though eventually).

Had two mechanics look at it, last
mechanic replaced a long black box,
forget the name, but had 3-4
comparents in it, and it was about
1.5 feet long. And that replacement
did exactly nothing to fix it (except
cost me $385, Bleh)

Thanks for anyone's help!

7 Answers

Tom Demyan

Could be misfires. Check Engine light on? Maybe a fuel issue?


Thanks so much for the reply Tom! Check engine light not on. Both mechanics checked spark plugs. Have changed fuel about 5 tanks, so prob not bad gas. I do have an issue in the fuel system telling me "tighten fuel cap", but the Saab dealer couldnt even find it with the smoke machine, and both mechanics said that shouldn't be causing the jump.


Pull the vacuum hose on the fuel pressure regulator. If fuel comes out of the regulator, its diaphragm has failed.

1 out of 1 people think this is helpful.

Thanks Goodwrench, i will give that a try and see if that is the issue. Any other things to try while me (or my mechanic) is in there?


If It turns out that the regulator is leaking, after replacement, check the plugs again. They will be carbon fouled. What happens when the regulator leaks is,.... after the engine is shut off, it will leak-off residual fuel pressure into the vacuum hose. When you start the engine, it immediately sucks that fuel into the engine, flooding it (Hard start). Every time this happens, it fouls the plugs a little bit, until you start noticing a misfire due to the carbon build-up. For now, this is my best guess. The only other things I can think of is a leaking fuel injector(s), or vacuum leak.


I think Goodwrench707 may be on the right track. Sometimes the hoses can develop hairline cracks. In my case, the engine would not idle correctly. The long black box you're talking about sounds like the ignition cassette - sits on top of the motor and engages onto the spark plugs. Finally, believe it or not, you must use NGK plugs.


Just in case this issue hasn't been fixed already, it sounds to me that its the throttle body. I replaced mine on my '02 saab 9-5 for similar issues. Has been great ever since. It is one of those "common issues" on the 9- 5s of that era. I believe the bba reman remanufactures those if you don't want to shell out the $400 for a new one. It sounds like the 1 1/2 long black box you had replaced is the DIC (direct ignition cassette). It could cause the car to jump/shake while acceleration due to misfire, as thats pretty much the ignition coils, spark plug wires, and a handful of other sensors all rolled into one component.

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