Ignition timing on Ford fuel injected engine with electronic ignition.

I took my 1992 Ford F-150 (6 cyl 4.9l, fuel injected) to a test only station for smog check. The technician said it failed the visual inspection because the timing was set to 0 degrees BTDC and was supposed to be set to 10 BTDC. It thought this was very odd since neither I nor anyone else I am aware of had touched the timing. I looked it up in my shop manual, and it says that the timing is not adjustable - that it is set automatically by the computer according to engine conditions. The test form I was given by the smog test shop said the timing was to be checked to "00" which I assume to be the 0 BTDC that the technician said was wrong. How can I confirm how it is supposed to be set? The test station will re-test for $15 if I take it back, but if they are looking for the wrong setting it won't do me any good, but just getting into an argument with the technician won't help unless I can prove what is correct.

Answer:

The smog technician is correct; ignition timing on your Ford should be set to 10 BTDC initially, and then controlled by the engine control computer. An important point to note is when the ignition timing on your Ford is checked, the inline spout connected needs to be disconnected. I have to assume the smog technician disconnected the connecter and then checked timing since this has been standard on Ford trucks for many years. The inline spout connected should be located near the drivers side wirewall, and should be yellow or white in color.

posted by SmogTips Support