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Pete, Buick Technician
Category: Buick
Satisfied Customers: 28772
Experience:  17 years Buick Technician experience and training.
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Random misfire in my buick 1997 lesabre and it uses too much gas

Resolved Question:

I have a random misfire in my buick 1997 lesabre and it uses too much gas
Submitted: 5 years ago.
Category: Buick
Expert:  Pete replied 5 years ago.
Hello,I will be glad to try and assist you with this,Welcome to Just Answer.


I just need a little more info to assist better.

When does this misfire happen?

Have fault codes been checked?

Do you know which cylinder is misfiring?

Has anything been tested or replaced/checked to try and correct or locate this problem?

Let me know so we can continue,Thanks Pete!
Customer: replied 5 years ago.
the computer said random misfire. low idle is bad all the time
Expert:  Pete replied 5 years ago.

There are scan tools out there that can be plugged into your vehicle that can display each cylinders misfire status,this will point out which cylinder is misfiring.

Then once located on which cylinder is misfiring then the compression needs tested on that cylinder and compared to the other cylinders compression,if it is 15 pounds or more different then the rest of the cylinders then this is a compression fault and is most likely a burned intake or exhaust valve in the cylinder head.

If the compression is o.k. then next is to check for spark on that cylinder with a spark tester or timing light.If you have no spark for that cylinder then the most common to fail and cause this is either a faulty spark plug wire or ignition coil.Check the spark plugs as well and make sure they are o.k.Spark plug wires should be replaced every 5 years or 100,000 miles whichever comes first,these are common to fail and cause misfires on this engine here.

The fuel injector will also have to be tested using a fuel pressure test gage and a fuel injector pulse tool to pulse each injector,the fuel pressure drop should be close to the same,if one injector is 1.5 to 2 psi different then the rest then that injector is at fault and needs replaced.

This is the best way to locate the misfire.This will also cause poor fuel mileage as well and once corrected the fuel mileage should come back.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!
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