Ignition timing to advanced at idle
 

Good day to everybody: I'm new to the site so a quick rundown on myself. I'm a Toyota fan and have been for some time. I own a 1979 Fj40 in not bad but could be better condition, a 1998 Tacoma 4x4 3.4 with rear locking diff, 2006 Vibe( I"ll call it a Toyota) and a 1992 Camry 2.2, that I just acquired. I've been an Aircraft Maintenance Engineer (A@P Mechanic in the United States) for the last 24 years.
I have a question about the camry. It has 331,000 kms on it and is in not to bad a shape. I've been going over it to get it ready for a safety and an emissions test. Its idle rpm was fine but a little rough.The p/o told me he had replaced the distributor but didn't set the timing. I, checked it and set it properly,10 degrees btdc according to the factory manual. After pulling the jumper according to the manual the timing should have returned to between 0 and 10 degrees btdc; instead it goes to about 13 degrees. There are no codes stored in the ecm, no vacuum leaks that I can find( and in the middle of the green on my vacuum gauge at 750 rpm. It seems to run fine on the road. I'd really to like to know if this is correct or what might be causing it before it is subjected to the E-test. Any help would be appreciated. :)

Don't know.

The idle speed is 750 +/- 50. Perhaps the advance would drop if the idle dropped to 700 rpm. Was the engine warmed up when checked, trans in neutral?

What does the inspection consist of? Does the shop actually check the advance setting? Or is it just a tailpipe emissions test.

The computer does not monitor every engine sensor thus the CEL would not activate if one of these non-monitored parts failed completely.

Some owners have moved the distributor housing for experimentation purposes to see what gains can be made. Otherwise if the base timing is set per procedure and the engine idles and runs well, everyone takes it for granted the computer will do its job.

Thanks for the reply Toyomoho: The engine idles at about 750, but when under a load such as rear window defrost or cooling fan cuts in it drops a little, maybe to 700. Timing doesn't really change at that time. It was warmed up and in neutral(manual trans). The inspection is a tailpipe inspection done at idle and at a certain rpm under load on a "dyno". The only sensor that I've tested is the air intake temp and it meters correctly. When I get a chance I'll test some others, maybe in order of ease to get at, and also check the spark plug gap, just can't seem to find that particular spec.

Gap might be .043 inch.

I doubt if this little advance will have that much effect on emissions for the car to fail the test.

Thanks for the gap info. I must admit part of the reason of looking into it is to see what I can learn from it. I'll post any interesting results.

Ron