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pinging, flutter and no power

3K views 10 replies 5 participants last post by  saabjoe 
#1 ·
I have a 98 saab 900, and it recently started acting like it has no power, turbo flutter after letting off the throttle and severe pinging when accelerating. The boost gauge reads like I am boosting, but feels like there is no boost. I just bought the car a few weeks ago and am stumped. First turbo car I've owned.
 
#3 ·
Welcome to the forums! Because of the nature of the Saab direct ignition system, you should never hear pinging. If it were to ping, it would be an extraordinary mechanical system failure to blame. As such, your CEL (check engine light) should illuminate and blink whenever you experience said pinging.
Given the information thus far, I can only speculate. You MUST be running the correct plugs, which are NGK BCPR-7ES-11. I don't care if it ran well with X. The car can use this plug, the plug from the T7 motor, which is PFR plug, and a racing plug, also from NGK, that is 30+ a plug, so i doubt that you have them.
The fact that it pings so terribly and the ECU seems to allow it (normally, the ECU pulls boost to almost 0psi in catastrophic knock like audible pinging) points to a problem with the DIC or the plugs, or both.

You should really run premium fuel, too.

Put your hand over the muffler; is there s a healthy flow of exhaust or is it a paltry puff? If it is weak, your cat could very well be plugged, which would make the poor thing knock its head off.

How old is your fuel pump? How many miles are on the car?

These are fairly simple cars, and you've come to an excellent forum as there are quite a few Saab repair gurus. However, we need a lot more information than you have given us. So, for future reference, please include the code for the CEL, which is conveniently given in a blink sequence (The Saab NG900 - Trionic Flash Codes) or you can go to Autozone and have them read for free.

As for your fluttering; the stock diverter valve, which sits right behind the radiator on top of the engine (google it and you'll see) is a known weak point in these cars. When they fail, they typically start to honk like a goose on throttle letoff. After that, they fail completely and you'll get flutter sounds. You may have also just popped off the vacuum line that goes from the throttle body to the diverter valve.
Good luck and I hope the above helps!
-Cm
 
#4 ·
A vacuum leak at the intake manifold will sometimes make the BPV flutter. Check all the vacuum lines and the couplers in the intake tubes from the turbo to intercooler, and intercooler to throttle body.

And all the stuff that Cm452 suggested.

Welcome!
 
#5 ·
Thank you for the welcome, I really love this car! I have no cel. I replaced the plugs when I bought the car and used the pcpr7es11. I have only run premium in the car since I purchased it, and inspected for vacuum leaks and found a hose from the fuel pressure regulator to the throttle body was rotted and disconnected so I replaced that one and a few others that seemed to be in bad shape. The car has 238k on it and the engine has 70k on it. The exhaust is flowing good with no puffyness. Car doesn't smoke at all either. I'll see how it is after I drive it with the new vacuum lines and order a bpv. Thanks again, I'll keep you updated.
 
#8 ·
After replacing the vacuum lines and installing the new bpv, there has been an improvement but still lacks in power I feel. There is a whistling sound on acceleration so I think there is a small boost leak somewhere. I know there will be some whistling because of the turbo, but it seems excessive to me. Possible boost leak?
 
#10 ·
That was my first guess.
If you haven't yet, give the car a once-over.
Do the basic maint. of new plugs, with dielectric grease,
filter(of your choosing), new vacuum hoses (all of them!)
Run some seafoam or fuel system cleaner through the gas to clean up gross varnish/carbon from cheap gas run in the past.
The t5 is MAP, so you shouldn't have any running issues with an intake leak, but it can certainly make the bpv not operate correctly.

Don't go jumping of a ledge, yet. Start small. It's almost a 20-year old car. if it has any original rubber hoses left under the hood, they're due for replacement.
 
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