1979-1993 & 94 Conv [Subscribe to Daily Digest] |
Let me "flesh out" that reply a little bit. I've owned 12 Saabs, about 4 of them were 8 valves, but only one turbo.
The Turbo was a nice '89 conv. that had been fairly well taken care of, with the exception of vacumn hoses. I bought it cheap because it had a burned valve. When I got into it I found the vacumn hoses were in bad shape and I found a couple of cracked hoses with large leaks. I believe these cracked hoses were the cause of the burned valve.
Vacumn leaks are an amazingly common problem with Saabs and idle hunting. You can always tell you've knocked off a hose during an oil change when you go to start the car, it tries to start, then dies immediatly. You give yourself a dope slap, make a sound like Homer Simpson, re-attach the hose and the car starts right up.
Saabs control the idle be sensing RPM and allowing filtered air into the intake via the AIC valve, which is essentialy just an electronic foot on the gas pedal. There is a fat hose that goes to the AIC valve that gives it filtered air just before the throttle plate, then another hose that returns to the intake manifold after the throttle plate. Hence the "electronic foot on the gas" analogy.
The system works great as long as there are no phantom vacumn leaks. When there is a vacumn leak, (and it may be a slight one or may be a cracked hose that varies the leak with engine temperature,) then the engine is getting intake air via that leak instead of the filtered air that the AIC valve would provide. As the leak gets larger and larger, you'll have alot of air getting to the engine that has not gone past the AMM, the air mass meter. The Saab is getting more air then the computer thinks it is, the engine is running lean and voila!, you burn a valve.
Your vacumn hoses might all be in place, but if they are very hard and brittle then they may not seal around the fittings and will allow air the leak into the intake. Inspect the vacumn hoses for condition. They get hard with time due to temperature and gas fumes, I believe.
There is a small hose that goes to the PCV valve and it is inside a fat foam rubber hose. Since the small vacumn hose is inside a larger hose, it can age and crack and ever break and you won't know it. That hose is a prime suspect. Vacumn hoses are cheap, all you need is 10 ft of hose and a pair of scissors to replace it with new hose.
The lines to go to and from the AIC valve tend to lose their seal with time. I use zip ties around the ends to keep them sealed well.
There is a charcoal cannister in the left front fender well. It looks like a plastic coffee can with a couple of lines going to it. Saab runs a hard plastic line to that canister, with a rubber coupling line. The short section of rubber line will deteriorate with time due to the excessive gasoline fumes. It cracks and starts to leak. This cannister is sort of "out of the way" and it's a good place to check. A flashlight is helpful. The rubber coupling line, which is only about 1" long, should not have any cracks in it. This is one of the FIRST places I look when a car has idle problems.
If you've had a leak into the AIC valve it will have accumulated dirt, oil, etc. in the valve. I cleaned mine with a little gasoline (poor it in the valve, but your finger over it, shake it up, repeat 2-3 times.) Then I used some graphite lock lubricant (dry graphite, comes in a tube, cheap) to lube the valve. Shake out the excess and re-install. Works great.
Hope this helps,
Ted
posted by 67.75.184...
, Thu, 20 Nov 2003 14:18:36
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
