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Saab 9-5 Aero randomly turning off when driving

511 Views 19 Replies 6 Participants Last post by  lucky7s
So I've been having this weird issue with my Saab as of recent. Basically a couple days ago I was washing my car after doing a 8 hour road trip and when I was leaving the self service car wash place, the car randomly would shut off after starting it struggling to idle right. Only way I manage to get it going is gassing it on start up and then off I went. The next day it started fine but when driving it just randomly turned off and I had to start it again while rolling which was sketchy.

I'm thinking it might be the fuel pump because there have been moments where my gas gauge will just not work for a couple of days (which is what happened the last 8hour drive I did a month ago but it fixed itself), but I'm not totally sure since it was apparently replaced when before I bought the car 3 years ago but its likely a non-OEM part. The CPS sensor was done a year ago cause I had a similar issue which turned out to be the upper idler pulley so those two things were done recently, and my DIC was replaced like 2 years ago with an OEM part so that should be good. But yeah I am worried of it dying randomly on a windy road or something so I wanna get it fixed. When I've started the car cold it'll sometimes jump rpms a bit and then drop down vibrating a bit so there's that.
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Does it only happen when the car is warm? (Ie- of a cold start?). If so I would suspect a cps, especially if it was not a Bosch. If not a Bosch, change it
the fuel pump usually does not cut in and out unless there is a loose wire or loose connection
 

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Discussion Starter · #6 ·
Does it only happen when the car is warm? (Ie- of a cold start?). If so I would suspect a cps, especially if it was not a Bosch. If not a Bosch, change it
the fuel pump usually does not cut in and out unless there is a loose wire or loose connection
So the first time it occured it was cold, and the car wouldn't get any power to stay on unless I gassed it.

The second time I was driving with a fridnds and it shut off as if it was shut off (ik the person in passenger didn't twist it off either)

It's been like two days and issue hasn't come back, I think it was a Bosch CPS but might replace it again in case.
 

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Discussion Starter · #8 ·
When it stalls does it feel like the key has been turned off (ignition) -OR- does it gradually lose power (fuel)?

If it’s “ignition” it could be the CPS. What brand CPS was installed?
When I was rolling it was like it started to lug a bit and then shut off, when I cold started and had it happen it would start right up and then struggle to stay on until it shuts off.
 

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Last week, my 9-5 CPS quit without any warning (luckily in my garage) but a few years ago, my Jaguar X-Type CPS began to act up during cold start warm-ups and a few weeks later started to stall once warm - so it still could be the CPS which won’t always trigger a CEL. You can test CPS resistance with an ohmmeter: trace wire from CPS to the connector (if Bosch it’ll be blue). Unplug it and test the three terminal combinations (1-2, 1-3, 2-3) on the sensor side of the connector. One combination should show 875ohms +/-100ohms if it’s in spec. If not replace it.

A slow stall could also be fuel-related but as others have said it’s unlikely that a fuel pump will cut out and in, but who knows. Get a fuel pressure tester (AutoZone, Advance, O’Reilly, etc. loan them) and attach to fuel rail fitting. You should see 40psi when key is turned on (not start). Then, with key off pressure should not drop below 33psi or so for at least an hour.
 

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Last week, my 9-5 CPS quit without any warning (luckily in my garage) but a few years ago, my Jaguar X-Type CPS began to act up during cold start warm-ups and a few weeks later started to stall once warm - so it still could be the CPS which won’t always trigger a CEL. You can test CPS resistance with an ohmmeter: trace wire from CPS to the connector (if Bosch it’ll be blue). Unplug it and test the three terminal combinations (1-2, 1-3, 2-3) on the sensor side of the connector. One combination should show 875ohms +/-100ohms if it’s in spec. If not replace it.

A slow stall could also be fuel-related but as others have said it’s unlikely that a fuel pump will cut out and in, but who knows. Get a fuel pressure tester (AutoZone, Advance, O’Reilly, etc. loan them) and attach to fuel rail fitting. You should see 40psi when key is turned on (not start). Then, with key off pressure should not drop below 33psi or so for at least an hour.
Issues that are intermittent can be maddening. The fuel pressure test will probably be normal. The real time to test the fuel pressure is when the car is acting up.
 

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The CPS never throws a code as it is failing. So if the check engine light does not come on when you stall, it points me more in that direction. If you still have issues after you replace the CPS, then I would consider borrowing a DIC. With the 4 Saabs I have, I’ve yet to have a DIC fail on me without adequate warning- a check engine light coming on is my warning.
 

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I’ve yet to have a DIC fail on me without adequate warning- a check engine light coming on is my warning.
I've had two DIC's fail in the same way as the OP, touch the gas and it's like someone reached down and turned off the ignition for a second then the power comes right back on as soon as you let up on the gas a little, no check engine light.
 

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Discussion Starter · #14 ·
Update: I got a P0455 and the car hasn't turned off when driving, but will sometimes shut off when starting up. I doubt it's the gas cap so I'm going to redo the EVAP hoses and some of the vacuum lines, haven't been making full boost for a while according to OPENSID so it might be that honestly.
 

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P0455 is a large EVAP leak and won’t impact drivability. However, if the EVAP purge valve is stuck open it will trigger the code and could cause starting problems especially after filling the tank: vapor which is displaced by liquid fuel is forced through the EVAP line into the throttle body, causing a rich start condition.
 

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Discussion Starter · #16 ·
P0455 is a large EVAP leak and won’t impact drivability. However, if the EVAP purge valve is stuck open it will trigger the code and could cause starting problems especially after filling the tank: vapor which is displaced by liquid fuel is forced through the EVAP line into the throttle body, causing a rich start condition.
Maybe it's that because when the car is totally cold (like in the morning or after it being parked for a couple hours) it starts up perfectly, but when it's warm like after I stop at the store or something it'll get the start up issue.

On the edge of the TB there seems to be kind of like some residue too, I cleaned the TB not too long ago but noticed that on the outside of it, I can maybe snap a photo later.

Is there any way I can test the solenoid or clean it?
 

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It still sounds like the CPS. See my post #9 for testing it. A failing CPS will result in stalling and/or difficulty starting.

The P0455 code is unrelated and more likely a hole/split in an EVAP line (a mouse chewed a hole in my 9-3’s line on top of the tank), a rusted fuel fill tube or vent tube that’s attached to the fill tube. A stuck open purge valve is uncommon and won’t cause the engine to stall.
 
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