AskPatty Certified Female Friendly Logo
My Mercury Cougar is missing. We replaced all spark plugs and coils on sat and it is missing a little still. I also added fuel injector on Thurs. Anything else I should check or replace? The car has 160,000 miles, V8 and I get 26 miles per gallon. Thank you

Answers from the Automotive Experts

Judy Curry, Co-Founder and Vice President of Marketing at Currys Auto Service Emily, Our team suggests to try having a compression test run on all cylinders. If the compression is below 125 psi that is the likely cause of the “misfire”. This type of repair is costly, may be a leaky valve. If the compression is good, start looking for an air leak at the intake manifold. This can be done with an explosive spray cleaner (carb cleaner, not brake cleaner). Care should be taken NOT to spray coils or exhaust as a fire may erupt. Hope this helps and good luck!

Colleen McGee, Driving Instructor at Americas Driving School Hi Emily Has the fuel filter been checked for replacement?

Amanda J. Pierce, MBA Emily, Provided that you also replaced the spark plug wires in conjunction of your spark plugs and coil packs I would check your idle air control valve.

Barb Petrey, President - DBK Enterprises Inc at Jiffy Lube Change the spark plug wires too.

Helaine Kurot, Owner/Technician at 360 Automotive Have a qualified techician check for relative compression before you put any more parts on the car. If the base mechanics are not working correctly, changing more parts will not fix this. Incorrect sensor readings wil also cause poor drivability/misfire concerns. Lazy 02 sensors, MAF, Idle control, vacuum leaks, etc. You will be much better off having this properly diagnosed than continuing to replace parts.

Contribute to this question:


blog comments powered by Disqus

Related Mercury Cougar FAQs


  • Hello, My name is Steven. I live in Charlotte, NC. I have a 1999 Mercury Villager ... Read More

Need Car Advice?

Ask The Experts!

Find Cars For Sale

Help Our Charities