danlablanc Posted October 5, 2008 Report Share Posted October 5, 2008 89 Cutlass, 2.8, 245k on engine, started with poor fuel economy and low power. Cat red hot on highway. I now think low vacuum is causing car to run rich. I have installed new injectors and replaced my exhaust. Checked to make sure ALL vac lines are sealed. I even replaced the intake manifold gasket, lower and upper. Still have low vacuum. Cannot get more than 15" steady at idle. Could this be mechanical? Quote Link to comment Share on other sites More sharing options...
Night Fury Posted October 5, 2008 Report Share Posted October 5, 2008 Welcome and congrats on that many miles! Unfortunately, I have no help. Maybe the vacuum ball? Quote Link to comment Share on other sites More sharing options...
Andrew Posted October 5, 2008 Report Share Posted October 5, 2008 whens the last time the o2 was replaced? Quote Link to comment Share on other sites More sharing options...
danlablanc Posted October 5, 2008 Author Report Share Posted October 5, 2008 02 sensor replaced since exhaust glowed red, about a week ago. Quote Link to comment Share on other sites More sharing options...
Addicted To Boost Posted October 5, 2008 Report Share Posted October 5, 2008 Is the cat old/bad/clogged? If the cat isn't old, it can turn red from excessive fuel. Make sure you are getting spark out of all 3 coils and your ICM is good. For the low vacuum, be sure all your vacuum connections are all connected and not leaking. They do pop off the back of the intake manifold on occasion. In front of your drivers side front wheel, there is a vacuum ball- make sure the vacuum line is hooked up to that and the ball isn't cracked. I had a low vacuum issue and my vacuum ball had fallen off! If you don't find anything after that, do a compression test on all 6 cylinders. Quote Link to comment Share on other sites More sharing options...
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