Tcat55371 Posted January 23, 2006 Share Posted January 23, 2006 Today Austin and I put new tensioners, idler pully and timing belts on my XT. I ran some GUNK engine degreaser in the oil for 5 minutes and put in new Schaffer oil in it. While the car was running he pulled the oil cap off the filler tube and the car all most dies. Just curious what the reasoning is behind this. I have never seen a car do this before. Is this because of the turbo? Quote Link to comment Share on other sites More sharing options...
NoahDL88 Posted January 23, 2006 Share Posted January 23, 2006 you might check your PCV, the only thing i can think of is that its sucking in air through the PCV and thats leaning it out, its a long shot, but the best i can come up with. Quote Link to comment Share on other sites More sharing options...
shawnsbrat Posted January 23, 2006 Share Posted January 23, 2006 Crankcase is under a vacuum from the pcv system,You create a vacuum leak when you remove the cap.Probably normal? Can a subi tech verify this? Im just a gm tech,lol Quote Link to comment Share on other sites More sharing options...
subiemech85 Posted January 23, 2006 Share Posted January 23, 2006 shouldn't decrease engine speed much, I added oil while running, no problem Quote Link to comment Share on other sites More sharing options...
NoahDL88 Posted January 23, 2006 Share Posted January 23, 2006 Crankcase is under a vacuum from the pcv system,You create a vacuum leak when you remove the cap.Probably normal? Can a subi tech verify this? Im just a gm tech,lol Just a GM tech? I think everyone here knows that its not easy keeping the General on the road, you're no tech, you're a miracle worker. Quote Link to comment Share on other sites More sharing options...
Turbone Posted January 23, 2006 Share Posted January 23, 2006 Turbo engines are a closed system. When you take the cap off it causes a big vac leak and dies. Quote Link to comment Share on other sites More sharing options...
Subaru Jim Maple Ridge Posted January 23, 2006 Share Posted January 23, 2006 I don't normally answer a thread where someone has already given the answer, but Turbone is entirely correct. Speculation sometimes takes people on a long trip to nowhere. Quote Link to comment Share on other sites More sharing options...
Mark Humble Posted January 23, 2006 Share Posted January 23, 2006 It's normal. When you take the cap off you're letting air into the engine that didn't go through the MAF sensor first so the ECU doesn't know about it and can't adjust the fuel to compensate for it. Quote Link to comment Share on other sites More sharing options...
Cougar Posted January 23, 2006 Share Posted January 23, 2006 Say whaaat? Quote Link to comment Share on other sites More sharing options...
idosubaru Posted January 23, 2006 Share Posted January 23, 2006 i've seen NA EA82's do this as well. i've replaced the oil cap o-ring, on an EA82 that wouldn't idle unless i pressed really hard on the oil cap?? weird, but i'm an XT6 owner and they don't do that. always wondered why. Quote Link to comment Share on other sites More sharing options...
shawnsbrat Posted January 23, 2006 Share Posted January 23, 2006 It's normal. When you take the cap off you're letting air into the engine that didn't go through the MAF sensor first so the ECU doesn't know about it and can't adjust the fuel to compensate for it. Ya,maf does get confused,Some cars are more sensitive than others.For example the chevy cobalt will set a check engine light (lean dtc) if the oil cap is off or dip stick isnt seated. And Ive seen some german cars hunt and stall when the cap is removed.Some cars you dont even see a change,Ok this topic is definately beat into the ground now!LOL Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.