RPM's/turbo boost fluctuate at highway speeds

[sgp9-5er]

Anyone ever experience subtle fluctuation in the RPM's at highway speeds? Just occurred last night, driving at 65-70 and I could feel variations in power. Not sure if it's some sensor or what, but it was definately noticeable. TIA.

[protech5]

I would bet DI or fuel pump

[sgp9-5er]

Not real familiar with SAAB parts, what is the DI? Replaced the fuel filter last summer, I believe for the first time. Does the fuel pump go after 9-10 years?

[protech5]

http://www.thesaabsite.com/95/95ignition.htm#IGNITION+CASSETTE+&+DISCHARGE+MODULE

[sgp9-5er]

Hey, thanks. I will check the DI out this weekend. Will let you know what I find.

[sgp9-5er]

Hey Pro, I have almost 80,000 miles on her. Light actually for a 2001, but the spark plugs are original. Think they should be changed out?

[protech5]

I would check the DI cassette. Did you see the testing procedure?

[sgp9-5er]

Prot, sorry for the absence...where are the test procedures located on the site? Thanks, Steve

[sgp9-5er]

protech, how do you test for this?

[protech5]

Look at the faqs. Info there

[madmax26]

Hi All

My 2003 Aero started to do the same thing.

It doesn't do it all the time though. Sometimes it'll run fine on the highway, and then sometimes just starts to surge like crazy. Today it was doing it around town.

I've done fuel pump, crank pulse sensor, fuel filter, spark plugs, vacuum hoses, PCV up grade, by-pass valve, thermostat, and temp sensor.

Could it be the throttle body?

Mark

[dondahlquist]

My 2004 Aero does the same thing...both the on the highway and around town......I've replaced crank sensor, tried two sets of plugs, 2 DI cassettes, very intermittent and every time I take it to the shop it runs fine and no problem can be found. Any one have ideas?
Don

[protech5]

Sounds like a boost solenoid

[sgp9-5er]

protech, I am still having some of these issues. I will read up on the boost solenoid. There is a turbo regulator as well, isn't there? There has to be some air flow or fuel flow sensor that is failing, and giving incorrect feedback to the control module.

I will post my findings.

[sgp9-5er]

Don,

Have you had any luck fixing your issue?? I have also replaced the same parts you have. My '01 will idle funny sometimes, will intermittently surge on normal acceleration, and fluctuate at highway speeds.

I will post what I find, hopefully help both of us out.

Steve