14th Jan 2006, 23:03

A tune up was done on this cougar about 8 months ago. I tried fuel injector fluid as well. I am not sure how to check the O2 sensors without paying for a computer diagnostic, which is so expensive. Thanks for the advice, I guess I will have to do something soon because a blown manifold would be bad!

15th Jan 2006, 18:13

I guess the first question is, who did the tune-up? I've had friends who paid a couple hundred dollars for a tune-up, but whatever the garage's definition of that was, it didn't include a distributor cap, plug wires, or spark plugs. Pull the plugs and confirm they were actually changed. Check the color of any deposits on the electrode. Heavy black soot is a sign it's getting too much gas; white is a sign it's running too lean; a normally operating cylinder should leave plug deposits that are light, creamy brown. The other simple thing, keep using the fuel injector cleaner, just one bottle probably won't reverse years of accumulation.

You might be able to check your O2 sensor yourself. For any older car, a Hayne's Manual is a good investment, and they explain how to check just about everything. This is just a kind of switch that tells your engine's computer how to adjust the performance. I'm a little out of my depth on these, but it's possible that you could check the resistance or voltage with a circuit tester, and the Hayne's Manual would give the tolerance values. Seems to me that on one of the other comments, there was somebody who did a good job of explaining how to test these O2 sensors, and had a similar problem as you.

17th Jan 2006, 16:11

Great advice, thanks very much. When the problem has been fixed I will post the solution!

3rd Jan 2009, 19:31

Check your intake manifold. That's what happened when mine went out.

21st May 2009, 15:37

Might have a clogged catalytic converter, happened on my car (83 Olds)... cut it out and put a straight pipe in, noticed quite a bit of difference...

18th Dec 2014, 11:38

Check the idle control valve, it might be clogged. If not, your exhaust manifold might be cracked; that makes the car lose a lot of power. Also do make sure spark plugs are set to the correct gap space and are tight.