 |
|
|
1979-1993 & 94 Conv [Subscribe to Daily Digest] |
I'm trying to cure similar symptoms on my '85T. I've looked around, and all the sources I've seen say that before you go after things like the AMM, you have to make *absolutely sure* you have all intake air and vacuum leaks taken care of. Apparently, if there's any 'unmetered' air (air that enters the engine but did not go through the AMM) it can cause these symptoms at startup.
On the turbocharged cars there are MANY places air can leak in, especially the 16V cars with intercoolers. Check all the rubber fittings between the various ducts from the AMM to the turbo, to the intercooler, and to the throttle body. The elbow on the turbocharger inlet is especially prone to cracking. Also check the following for cracks or signs of possible leaking:
- The air hose from the Turbo bypass ('hooter') valve to the throttle body
- The 2 air hoses from/to the throttle body and AIC valve
You should also check all the 5/32" vacuum lines. You can take them off at the manifold end and suck on them and see if you get air through. Check that you can't draw air through the vacuum lines to the distributor advance unit, the turbo bypass valve (a common leak), or the fuel pressure regulator.
There's another line that goes to the vacuum reservoir. The reservoir has a check valve in it, and these can go bad, causing an air leak. It's also possible that there could be leak in any of the airflow control components in the dash.
There's another vacuum line that goes from the manifold, through the firewall, and into the dash, that connects to the boost gauge, the turbo pressure sensor and the turbo pressure switch. If you suck on this line you shouldn't be able to draw any air through it either.
There should be also be one or two lines from the manifold or throttle body to the ELCD (charcoal cannister), in addition to the (rigid) line that comes from the gas tank. If you have two lines you shouldn't be able to draw any air through the small one, but I think the large one will flow some air. If your ELCD only has one small line between it and the throttle body or intake manifold, I think it will flow some air (but I'm not sure about this and I'm not sure that this isn't a problem on my car. I have a new ELCD on order.)
On turbocharged cars check the three pneumatic lines connected to the APC solenoid, especially the one that plugs into the grommet on turbo inlet duct.
Another possible source of air leaks is the PCV system. This includes the PCV line (small line from manifold to valve cover, with a check valve in it on turbo cars) and the PCV breather that goes from the valve cover to the throttle body (NA cars) or to the air duct between the AMM and the turbocharger (turbo cars). If the crankcase and/or the PCV system are leaking air it will cause a problem. On our cars the crankcase breathing system is supposed to be completely closed, and, for example, opening the oil filler cap will foul up the running if things are otherwise working right. On my car there's no difference in the running if I open the oil filler, which makes me still suspect I have a lurking air leak -- you might try this test. One place I've heard of air leaks here is cracked engine oil dipstick tubes.
The last thing I can think of that may leak air is the brake servo unit. I suspect that if the servo is leaking air then braking will be affected, but it could be that they can leak air but otherwise seem to work ok. To check you can disconnect and plug the line to isolate the servo unit and see if the problem goes away.
Lastly, don't worry about cracks or leaks in the Cruise Control vacuum lines. These aren't connected to the engine air, and only interconnect the CC vacuum pump, the CC servo (on the gas pedal), and the clutch and brake switches (also the APC vacuum switch on turbo cars).
That's all I can think of. Let us know what you find.
posted by 67.183.219...
, Fri, 23 Sep 2005 04:37:11
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.
 |
 |
 |
 |
 |
