# Poor Gas Milage on 89 max



## CBPMIKE (Feb 2, 2005)

I have 89 max with 300,000+ miles. I have always got about 20mpg with the car. It has dropped to about 15-16MPG and with gas prices this is a PITA. I replaced the exhaust system completely and with the new cat I was unable to get a good seal (no donuts, just flimsy gaskets)and there is a leak at the cat unions to the pipe. Could this affect the Oxygen Sensor readings and cause it to lean out the mixture? I may also have a vacuum leak after replacing the heads. Could this also contribute to the problem? I was thinking of having the cat unions welded to eliminate the leak and I could remove the air chambers and replace the gaskets to try to eliminate the vacuum leak. Am I on the right track and are there any other suggestions? - Thanks!


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