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Discussion Starter · #1 ·
So the last mechanic told me "car is boosting fine," and said so with a smile, as if he thought the car was wicked fast.

Car is only going 1/2 into yellow. Feels like there is nothing there when I hit the throttle, couldn't even overtake a Kia on the road the other day. Maybe I just don't know how to wind the thing up properly, but doesn't this car make most of its power in lower RPMs?

I took it into new Saab guy this morning who has been working on Saabs 30 years now, he just calls me and says "Looks like the wastegate is frozen. You're actually getting *too much* boost, but we'll get a better look tomorrow."

I think he said base boost is like 4-5psi and I forget how much he said I was getting -- 12? 15?. What is stock max boost on a 1990 SPG?

Holy schnikees. My SPG feels like a slug, and I'm actually getting more boost than I should be getting?

I also had him put on the new Simons exhaust I got from thesaabsite.com

He commented on what a nice setup it was and asked where I got it.
 

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stock base boost on a SPG is like 5.5-6 psi. Max being around 13-15... IIRC. I lost my Bentley manual. Either way, that's not too much. You'd know if you were getting too much boost. I was running like 26 pounds a little while ago. But since I like the transmission to work I've scaled down a lot.

A frozen wastegate isn't a good thing, but I dont think you're gonna be in any danger driving normally for now.
 

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Maybe it is frozen. Maybe its not frozen closed. Maybe it is frozen closed but something else is messed up. Unfortunately it sounds like you have to wait till tomorrow to find out.

These cars really light up at say 3000rpm. If you slam it down in 5th at 1500 rpm you might not see anything until the revs climb, but it should take off eventually. You'll know it. A properly base tuned SPG should pull hard enough that the boost at least reaches the yellow/red line and you should feel some torque steer and lightness in the front end.

You should be giddy.

Unless you've been driving around in a honking v8 all your life and expect a hard launch from a dead stop an SPG should get your heart racing.

So if you're not getting any of that there's probably something up.
 

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Discussion Starter · #4 ·
Thanks guys... I feel a little better now. The only 900 I ever drove was a N/A 1980 GLi, and this one feels about the same as that one maybe, maybe less powerful than that one. I haven't tried "launching" it, and never will, but I could easily screech the tires on my old 900. This one, well, I want to drive it forever if I can, so no abuse... But if I hit the gas at 30mph I damn sure have been led to believe that this car is going to put a grin on my face. Not yet.

No torque steer that I've noticed, but as I said, I haven't really been that aggressive at takeoff.

I'm coming out of a Mazdaspeed6, but obviously I don't expect that kind of power from the SPG. But I did expect a nice boost of power when I put my foot down at speed. There's nothing here.

The thing that worried me is that the first mechanic assured me that "it's boosting fine..." and this is a guy who lives and breathes Saabs.

But I do think something is definitely wrong. I guess I'll find out tomorrow. If this guy doesn't figure it out, looks like I'll be getting my hands dirty.

Just wish I had more time to learn/do these things myself, but with a 4 month old, time is in short supply right now. :)
 

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When I first got my '89 it wouldn't boost for crap. 8+ month old gas, I guess. It'd get to about 1/2 yellow, then fall back from knock or whatever. 10 gallons of 91 octane v-power later (about what I put in ~5g at a time) and it boosted right up to the red, stayed there and had me planted in the back of the seat.

Dunno if you know Saturns at all, but my DD is one and...well about all it'll outrun is a Metro (that was FUN :D), so this SPG is a blast.
 

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It should haul major butt between 50 and 80mph. And although it may not blow away all comparisons in that range, the way it builds the power and throws it down with authority should be evident. Maybe your APC is not functioning and you're operating at base boost.
I had an 81 900 base model and it was fun too. There is a huge difference in power between my 82 T8 and that 81 non turbo. And there is a huge difference between my 82 and SPG.
My SPG is now in its final stages of being parted and I only bought it as a parts car. The thing had sat for 6 or 8 months and I've only driven it 2 miles (home). But when I gave it a a stomp at 60 (km/h) in 3rd on that drive I was astonished at the difference in power from my T8.
 

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Wouldn't a 1990 SPG have the mitsi turbo? If so then you can expect it to kick in early probably around the 24-2500 rpm range, it doesn't seem to kick in as hard as the garrett turbos, and it builds then tapers gently off. The garrett doesn't kick in till about 3000 rpm, but it really pulls when it does.

To me the mitsi is more refined and better for city driving.
 

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It would, stock, unless it went bad and was replaced by somehting else.

Check the APC box and harness to make sure that there is a good connection.

While the car electrical power is ON, unplug, and then plug the APC in. You should hear a clicking noise coming from the APC solenoid ( next to the ignition coil).

mikewitdaspike would recommend unpluggin the wastegate and running full throttle to make sure boosts 100%. ( a joke ;) , dont do it)
 

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DanF. said:
mikewitdaspike would recommend unpluggin the wastegate and running full throttle to make sure boosts 100%. ( a joke ;) , dont do it)
well, one or two runs wouldn't kill it :cheesy: well, shouldn't anyway :confused: mine held up ok
 

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I'd trust the boost guage more than your mechanic. Bottom line is, these cars are plenty fast if they are working properly. Yours isn't. Theres no special trick to winding them up, you press the go pedal, and it goes. My T16S (SPG) can keep up with a lot of new, expensive metal.

DanF. said:
mikewitdaspike would recommend unpluggin the wastegate and running full throttle to make sure boosts 100%. ( a joke ;) , dont do it)
Its a perfectly valid test, you should do this, and see if it boosts ok. Then hook it back up afterwards.
 

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This may be for the *Questions you thought were too stupid to ask* thread but can you lubricate the wastegate? Can someone provide a good photo of its location?
 

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stickman said:
This may be for the *Questions you thought were too stupid to ask* thread but can you lubricate the wastegate? Can someone provide a good photo of its location?
It's bolted to a bracket towards the lower front side of the turbo, and looks like a short cylinder with an arm going off of it towards the wastegate.

I don't think you can lubricate it, it isn't meant to be opened/servicable - in order to open it up you'd have to uncrimp the edges, pop it open, and then recrimp them with a visegrip or something. What you might be able to do is jiggle the arm around a bit, maybe loosen up some rust or something.
 

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philb said:
Its a perfectly valid test, you should do this, and see if it boosts ok. Then hook it back up afterwards.


Yes, agreed. Be careful though, as this will only test to see if the wastegate stays CLOSED at all rpms. I would suggest being in, say 4th gear, at 3000 rpms, and slowly easing upto 3/4 throttle. Don't mash the gas pedal, as you'd may get a very quick boost spike. But then you'd know your wastegate stays closed, as it should.
 

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Discussion Starter · #15 ·
Trouble was a faulty APC solenoid. Car seems MUCH more responsive now, right about where I'd expect.

The guy didn't even charge me an hour labor to diagnose & install the solenoid, and he gave me a used one instead of charging me for a new one ($$). Installed my catback exhaust as well, and didn't even charge me an hour labor for that either.

Think I found my new mechanic.

My car is FUN again!

That said, I'll definitely be checking what the base boost is at some point in the near future, when I can find time to work on the car again.
 
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