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Saab Story

I have a 1991 Saab 900 its not a turbo.

It misses really bad like it had fouled plugs i put Bosch platinum twos in it withe new cap and rotor and it still runs really bad.

Whats next? thank you for any help you can give me.

PS

I also replaced the fuel pressure regulator.



Plug wires? I would recommend sticking with OEM parts. It has been my experience that after market parts are less reliable in ignition systems. The fancy expensive designer parts tend to end up being less reliable and less efficient.

Why platinum plugs? For one thing, they’re needlessly expensive IMHO; for another, plats weren’t around in 1991 so the Saab engineers didn’t design the motor to run on them. Does Saab sanction the use of plats in that motor? Agree that plug wires need to be replaced at the same time for optimum performance.

As for what else it could be–the list is long. The way to shorten the list is to begin doing the recommended diagnostic tests and start ruling things out. You haven’t given enough info on symptoms for us to do that for you at a distance, but as always, driveability issues can result from fuel, ignition, air and/or vacuum failures. I’d begin by getting the factory service manual for your chassis, a decent multimeter and pressure gauge and go have some fun in your garage.

Miss firing####I pulled the wires cap and rotor off of one of my other Saab’s that runs fine. All the vacuum lines are in good shape and where they are suppose to be. It smells like fuel so i unplugged the vacuum line from pressure regulator and it still runs the same, "thought that maybe it was faulty and making it run rich… I did replace that with the one that was on my other Saab and it was working on that Saab just fine. No matter what parts I have put on this car the symptoms never change.
I think i need to find Saab guys, there are no codes to pull from the car. So I guess ill figure it out…and has far has the plugs, I notice the difference and I will always use them. My other Saab runs perfect but the transmission is bad this is why I pulled some of the parts off of that Saab to help trouble shoot the issue.
I plan on doing a compression test today but I doubt that’s it because just a week ago the car ran perfectly.

If someone is going to be snotty and offer no help except to say something snotty then don’t reply. Just shut up, if someone thinks they might have an answer I would greatly appreciate it.
thank you

You did not state how many miles are on the car and while engine problems with SAABs are extremely rare, the first step in diagnosing an engine performance problem should always be to run a compression test.

You always weed out the possibility of a mechanical fault first or you run the risk of replacing every part on the car in a futile attempt to cure something that won’t be cured.

Some more info might help.
Idles rough?
Misses at speed; surging, bucking going down the road?
Engine appears to rev up in a sluggish manner?

Well it has 200k on it should be good for another 100k. It misses wont idle very well and eventually dies, its starts hard and driving it sucks because it runs like a car that misses, bucks and hops and all that. I do notice that when I rev it up to around 4k it will run smoother of course but you can hear it will misfire then smooth out then misfire and smooth out again??

I hope I explained that right but its intermittently misfiring in all RPM ranges
I am going to do a compression test on it today so I can rule out bad valve or any of that. I have had lots of these Saab,s and I have never had one that I could not fix,except this one. If it would at least give me a code I could have more to go on.
I was even wondering if the EGR system was failing, but not sure I have a new fuel filter that I have been meaning to put on it but have not yet, i cant imagine that would cause it to misfire, I think I am getting to the point of suspecting the car might be possessed…lol ok that’s not funny but I am running in circles now. This car ran perfectly about 5 days ago, i go out to start it one morning and it rebels and taunts me with misfiring and poor run ability issues. And right now I don’t need that, I just need this sucker to run…thanks for all the information everyone has gave me, I do appreciate it.

When doing all this ignition work did you make sure you connected the plug wires to the correct cylinders?

Yes I did

Ok everyone thanks for the help, turns out it was the fuel pressure regulator making it run so rich that it seemed like it was missing…so just FYI
thanks again.