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Back To Basics

Quite often a problem is a small thing that should have been checked in the first place. We have to get Back To Basics.
» Part 1: Back To Basics
» Part 2: Air And Fuel
» Part 3: Spark
» Part 4: Engine & Electrical

Check the ignition timing. It may be computer controlled and no provision for adjustment is made, but how do you know the computer has it set right? It only takes a couple of minutes to check and if it's off, you found a problem. If the ignition timing is off, and provision for adjustment is provided, then adjust the ignition timing to the correct specification.

Check the engine vacuum with a vacuum gauge. At idling speed, an engine at sea level should show a steady vacuum reading between 14" and 22" HG. A quick opening and closing of the throttle should cause vacuum to drop below 5" then rebound to 23" or more.

If you have a cylinder misfire, check the compression in that cylinder. If it's good then you know the engine itself is sound and the problem lies elsewhere. If you have adjustable valves, make sure they are adjusted properly before doing anything. A tight valve will cause a misfire or backfire.

Electrical and Vacuum

The cardinal rule in any electrical shop is "Check the fuses first!" I don't know how much time has been wasted looking for an electrical problem, which could have been solved by replacing a simple fuse. At the very least it will tell you which circuit(s) the problem is in. Look at the wiring and connectors to make sure they are in good condition. Make sure they are clean and tight as well. Loose connections can cause a lot of weird, intermittent problems. That's why Ford developed the "Wiggle Test".

Check the vacuum lines. Make sure they are connected properly and don't have any cracks or breaks. Vacuum lines never break or rub through where you can see them. They always get damaged behind or underneath something. So. If you have to, remove the vacuum line and check it from end to end. My next-door neighbor was going to put a new Rochester four-barrel carburetor on his truck. When I looked at it, I found a broken PCV line behind the carburetor mount. I told him to replace that line and his truck would be fine. Almost an unneeded repair due to not checking the basics. If you get DTCs that indicate a rich or lean condition, it could very well be due to a vacuum leak.

Sometimes a driveability problem is caused by a lot of little things not bad enough in itself to cause a problem. But when combined with two or three other little problems, they make one big problem. If you can't find something obvious, then a good, through tune-up with a new distributor cap, distributor rotor, spark plug wires and filters should be the first thing you do. This will insure that most of the basics are good and this in itself, most times, could solve your problem.

Studies show that millions of dollars are lost every year because of misdiagnosed car problems. But you can keep this from happening to you if you take an hour or less to check the basics.

» Part 1       » Part 2       » Part 3       » Part 4
Additional Information provided courtesy of and Warranty Direct
© 2000-2007 Vincent T. Ciulla

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