joshmillslane Posted December 22, 2007 Share Posted December 22, 2007 Bear with me now - I'm not a mechanic, but I'm learning. I've been plugging away at my 2.8 trying to get this thing to pass Virginia Emissions. I started by installing a brand new Cat since previous owner removed it. This made the truck run 100% better, but I failed emissions with high NOx with other readings very low. So I did a minor tune-up. New Cap, Rotor, Plugs, PCV (They were all very bad - probably original with over 110k.) Adjusted the timing which was about 3 degrees retarded according to the Catalyst label. This made the truck run and start great - even better than before. Took it in for a retest today, and it failed again with even higher levels of NOx - all other readings were nearly zero. The tesing guy said it could be an EGR problem, so I decided to tackle the EGR valve replacement tonight. As I tore into it, I found the line to the EGR valve was disconnected completely. I went ahead with the replacement and connected that line. I also found another small line that was rotten and hanging from the PCV system I never noticed before. I fabricated a new line and connected it to a nearby electrical/vaccum thingamajig that was clearly missing a hose. The good news is that the truck started and ran, but with an extremely low idle. Driving it around is fine - the idle is just very, very low - almost stalling. Could a vaccuum leak cause a high idle? I'm wondering if the previous owners might have backed the idle down when this stuff was not connected and leaking, and I should just bring it up, or look for another problem. Thanks in advance for any ideas. Link to comment Share on other sites More sharing options...
86FUBAR Posted December 22, 2007 Share Posted December 22, 2007 yes a vacum leak could cause a high idle and that could have been "fixed" by adjusting the idle screw. best thing to do is go through all of the vacume lines and replace everything Link to comment Share on other sites More sharing options...
Oizarod115 Posted December 22, 2007 Share Posted December 22, 2007 yes a vacum leak could cause a high idle and that could have been "fixed" by adjusting the idle screw. best thing to do is go through all of the vacume lines and replace everything yeah, i did exactly what 86 said when i lost vacuum, wasn't thinkin and just backed it down manually... then i found my vacuum leak and was stalling out lol. stupid thing to do really :oops: Link to comment Share on other sites More sharing options...
carnuck Posted December 22, 2007 Share Posted December 22, 2007 First disconnect the EGR and make sure it isn't the "vacuum leak" Link to comment Share on other sites More sharing options...
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