Date: Sun, 16 Nov 2003 21:49:29 GMT
From: Paul Halliday <pjghnopsamyonder.co.uk>
Subject: EGR Valve


Good eve' fellow Saabers, I'm really not happy with the way my EGR vac pipes are setup on my 1989 900 T8. Pre-throttle, I have one take-off which runs across to the distributor capsule (I think that's the right word - this is the "vac advance" thingy, right?). I'm sure my old '88 900 T8 had two pre-throttle vac take-off points. This pipe has a T in it which goes to the two prong EGR temperature sensor(?) between number 2 & 3 cylinders. I can't help thinking, but correct me if I'm wrong, that the point of the pre-throttle take-off is to push boost across to the distributor capsule. But, surely this is also the pipe that re-circulates gas back into the pre-throttle. If the engine is under boost, this pipe will be blowing from the pre-throttle intake and therefore the EGR pipe will have no chance of re-circulating gas. It may be purely intellectual, but that can't be right. If it's not right, then I should do something about it :) I gather the EGR valve starts operating at about 2100 RPM. I'm often starting to go into boost by this point, with the boost gauge at the broken white part, so presumably gas is only re-circulated for a brief second on each gear change. Okay, I appreciate that it can be quite happily running on a motorway cruise, but I rarely do that kind of driving and spend probably 90 percent of my time either in start/stop city traffic or cranking between third and fourth on country lanes, turbo whistling away. I've been reading that Saab removed the EGR system from later cars. Can, or rather more importantly, should I disable the system? I've read a lot of opinions on a couple of forum boards, but I'm a lot more confused now about whether I should and how to do it. I also read that the UK MOT is a lot more harsh over emissions and a correctly setup T8 will fail anyway, so disabling/removing the EGR system is not really a great issue. Besides, the more I "turbo", the more I'm cleaning the air anyway :) How would I disable the system? Logic dictates that I should simply block off the vac pipe that runs to the pre-throttle position. Later, I can get a take-off cap to put on the EGR pump(?) under the intake manifold and remove the sensor (between 2&3 cylinder) and block up with a bolt of the right size and thread. Opinions and advice would be very much appreciated. Paul 1989 900 Turbo S http://saab.go.dyndns.org/

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