[Pwalls]

Hi,

My 9-5 wagon has the following issue:

Thermostat needle will drop to lowest point (off?) while driving. If I stop and turn off car and restart it goes back to normal range and all is fine.

While driving this morning it did this, I restarted continued on and traveling 65mph down the highway the check engine light flickered on and off a number of time but never came on totally and then the car felt some jerky as I pulled off the next exit. I continued down side road and it appears that between 40-50mph the car will be jerky/jumpy as I take foot off the peddle. Worse if I do it very gradually, but if I totally let off it jerks once and then rides fine at 40mph or lower. Also if I speed up it drives fine at higher speed-

Had car at shop Tuesday with this issue. The check engine light was on and was related to thermostat, but after resetting it appeared fine. They could find nothing , but after they put everything back together it drove fine all day Wednesday. Only to start again today-


So, I would love ideas because I do not see the two being related except maybe some common electrical issue or connection?

thank you;oops:

 

[MacNoob]

So is the needle still dropping to zero? Or you are just getting the jerky throttle action?

They are unrelated and you probably have two problems. How long since the throttle body has been cleaned?

 

[Pwalls]

yes, well at least the needle did this once today, but the check engine light is not on. It only flickered a dozen quick time on the highway this morning.

I just had the car serviced- 125,000 miles. I will have to see if they cleaned throttle body or not. Would this be done as course of normal major tune-up? They are usually pretty thorough-

They did replace ignition module, plugs, etc.. .

 

[fusionrx]

Thermostat dropping to zero would be failing thermostat temp sensor. This is a DIY job. See FAQ's.

Throttle body issue would probably be setting some codes off. Can you get to a Autozone etc or dealer to pull any codes?

The car is in limp home mode, the reason could? be a bad throttle body.

First and foremost is to remove the intake tube and clean out the throttle body. Then the codes needs to be reset and limp home switch/linkage properly set.
They should also check so that you have the software fix installed in fuel ECU that deals with the throttlebody problems. (narrow voltage gap).

If after all that the throttle still goes into limp home you probably need a new throttle body.

In my case the issue was the fuel ECU software update.

 

[Pwalls]

No codes for the throttle body issue, just one for the thermostat temp. sensor.

The check engine light is not on now but is in this limp home mode.

I'll check on the software fix and cleaning throttle body, etc. .. . .

Thank you-

 

[MacNoob]

I didn't see anything that makes it look like you are in limp home. In limp home the car barely runs, idles at about 500 rpm, you have no cruise control, no air conditioning, and you will have a CEL reporting throttle body problems.

 

[Pwalls]

Okay- was not sure what the limp home mode was for sure anyway, but you are correct:

I have cruise, air, normal idoling, and no codes.

I just have that pronounced studder/jerkiness when I let up on the gas when going 40-50mph, mostly right at 45, but it is hard to tell for sure on these frost heaved roads in New Hampshire ;-)

 

[saabfire]

They should also check so that you have the software fix installed in fuel ECU that deals with the throttlebody problems. (narrow voltage gap).
In my case the issue was the fuel ECU software update.

Does this update pertain to all 9-5's or only certain years? Can the dealer tell you if it's been done?

 

[rweaver]

They should also check so that you have the software fix installed in fuel ECU that deals with the throttlebody problems. (narrow voltage gap).

...

In my case the issue was the fuel ECU software update.

I have a 2004 9-5 2.3T and am experiencing off and on quirky behaivor... this fuel ECU software fix...is that something that would extend to '04 models as well?


-R

 

[fusionrx]

Think that it applies to all of the earlier model cars. I never got a straight answer from the mechanic that suggested it, but the fault was present on my 2001 9-5 3.0L wagon.

Btw, if any of you frequent the other 'saab net' site, the mechanic in question is "Swedecar" who really knows his stuff.

 

[fusionrx]

At this point, I have to defer to a saab mechanic.

Maybe SaabScott can ask Anders if he can provide the reference dates on this software upgrade?

All I know is that I ended up being the one researching this fix (with the help of Saab net, b4 I found SaabCentral) and giving this info to the local Saab dealership. Their response was: "Oh yeah, that was the issue all along. We never thought to check that".

 

[Pwalls]

thermostat sensor and end of day issue

Okay , talked to mechanic and thermostat sensor was replaced. Could be a bad sensor or the actual thermostat?

The weird thing is I am driving home today and the thermostat is at about 7 o'clock and then goes off and check engine light comes on. I stop and restart and the car is very jerky/jumpy as I am driving and then thermostat needle goes right to 9 o'clock and the jerkiness stops. I could even set the cruise at 45 and it drove smooth all the way home.

I do not know-