Hi all, just had a quick question for you guys that I can't seem the answer to anywhere. Is there any possibility that a bad egr valve could cause the heat in my 1995 blazer to go into default mode? I'm having a bad idle problem and a hard time starting and an occasional stall, so I figured it's the egr valve already but I'm hoping this is also the vacuum leak I've been looking for that's causing the heat to go into default mode. In advance to this I have a bad input shaft seal that I'm looking at replacing due to the transmission fluid in my vacuum lines. I've also heard that it is the vacuum switch near the transfer case that's the problem there. Can anyone give me some clarification that way if I don't absolutely have to I won't drop the transfer case. Thank you all in advance.

 

EGR is only applied off idle to part throttle. An engine with EGR at idle wont run. An engine with EGR at full throttle wont run well.