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Discussion Starter #1
I just picked up my '94 Aero yesterday from Minot, ND. I'm from Canada and I bought the car from Marietta, GA. The car has 122,000 miles on it and is a very clean car. I've already fallen in love with it, just from the 4 hour drive home. I currently own a tweaked '89 900, which makes 241 whp and 291 wtq @ 22psi of boost. I needed to find a clean, fun and reliable daily driver, and what better car than a 9000 aero. This car does not have traction control, which was the only way I was going to ever buy an Aero.

I do have one question or concern with the car. I noticed that the factory boost gage does not read any vaccum. It just sits in the center point between the white and orange, but it does show boost going into the red when I get on her. My thoughts are that either the boost gage is broken or there is a vaccum leak somewhere. The car seems to run perfect, not showing signs of a vaccum leak, but I'm sure these Trionic cars can adjust to a vaccum leak perfectly. Another thing that is weird is when I'm on it hard and take it up in the higher rpm range, the rpms will stick at the rpm I shifted at for about a second and then come down, but slower than it should. It's like the throttle plate is being held open for a moment. Here's my take on the situation regarding the boost gage and this sticking rpm. I think the rpms are sticking there because of a vaccum leak, which is drawing air into the engine between shifts, which then causes the rpms to remain there because of the air being supplied thorugh the vaccum leak. The sticking rpm only happens when I'm driving it harder. It will not stick when driving normally. Does anyone have any suggestions?

I also noticed that the cabin air sensor on the dash is rather loud, like a girgling sound. What's up with this?

What oild do you guys run in your Aeros. I run 20w-50 in my 900, but I'm obviously not going to run that on a stock engine. Should I run 15w-40 or just 10w-30 in the summer. I know that I will never put 5w-30 in any motor.
 

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My first guess is a leak at the dump valve. It'd explain both the lack of vacuum and the sticky revs, because the pressurized air can't vent properly. It has to go somewhere, so it's getting forced around, causing the revs to stick.

And as far as the cabin temp sensor goes, I haven't found one in a 9000/900 yet that doesn't make noise. You can try taking them apart and cleaning it, but I've never had luck with it. A new one is the best solution, albeit more expensive.

I've been running 0W-40 for a while, in a variety of climates, and have had no problems.
 

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Cliche` said:
And as far as the cabin temp sensor goes, I haven't found one in a 9000/900 yet that doesn't make noise. You can try taking them apart and cleaning it, but I've never had luck with it. A new one is the best solution, albeit more expensive.
Must be bad luck, or good luck on my part. I have tested three of these sensors, and none made any noise (originals in my 1987 and 1991, plus a spare that I got on eBay). They were quite dusty, so I cleaned with compressed air. But even before, they never made a sound. You'll need to remove the sensor from the back to get it out of the dash for cleaning. The easiest way is the pop out the clock with a small flat-bladed screwdriver on the top center, then reach in and push out the ACC unit from behind.


What's wrong with 5w30 oil? It's listed as an alternate oil grade in my 1991 owner's manual, along with 15w40. 10w30 is the primary listed grade.
 

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Discussion Starter #4
Funny that you mentioned the bypass valve. I forgot to mention that I can here compressor surge between shifts every so often. I guess I'll just fit my forge blow off valve. There should be no stalling issues with these trioinc cars, since there's no air mass meter, is that correct?

As far as 5w-30 goes, My dad had a couple bad expereiences with that stuff. He switched over his '81 BMW 733i to 5w-30 from 10w-30, when all the hype about how great 5w-30 was back in the early '90's. The motor didn't like it and it started blowing oil out the tailpipe. I'll just stick with 10w-30 or 15w-40.

I was reading the thread about the guy that bought the '96 aero, and someone mentioned that Fram oil filters are no good. That's all I've ever used on my saabs. What's wrong with the Fram filters?

Thanks for the advice guys?
 

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Correct, all the pre-trionic and T5 cars are perfectly happy with a blow off valve.

I don't know anything about Fram filters, I've always just used the Saab long life filters. They're not the cheapest, but if you make firends with the techs at the dealer, they might toss you a few for free.
 

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Jared S said:
I was reading the thread about the guy that bought the '96 aero, and someone mentioned that Fram oil filters are no good. That's all I've ever used on my saabs. What's wrong with the Fram filters?
Fram oil filters allow particles as large as 30 - 35 microns slip through.
Filters like a K&N oil filters trap all particles larger than 8-12 microns.

Also fram filters use cheaper quality paper in their filters, and cardboard / plastic where a higher quailty would use plastic / metal. In high flow applications, this can lead to failure.

IF you buy the best oil filter, its still only $12.00 and it lasts 10,000 miles.... your only saving a few bucks with a cheap cheap fram filter over a long period of time. I buy K&N for piece of mind, thats worth a lot in a saab.

As for fram air filters.... I have a forced induction with a relatively large turbo charger. I'm definitely not going to cheap out there and have some inferior air filter allow tiny particles to slowly wear away at my turbos mechanics because it cant handle forced induction. I went with K&N on this part too.
 

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Discussion Starter #7
Well the lack of vaccum at the boost gage was due to a broken bypass valve. I checked engine vaccum with an aftermarket boost gage and found that there was only about 3 in-HG worth of vaccum at the T which has the bypass valve line and the vaccum line that goes to the inside of the car. I checked the vaccum level at the opposite end of the intake manifold plenum and I got 16 in-HG. I popped in my Forge BOV and I had vaccum on the factory boost gage and the hanging rpm problme seems to be corrected. Now that there is a working BOV fitted the car overboosts in 2nd gear and hits fuel cut out. The APC solenoid is buzzing intermittently so I'm gonna look into that. I'll check my base boost and do some adaption runs with a good APC solenoid and hopefully the overboosting goes away.
 
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