93 Tercel timing question / problem

I have a 1993 Toyota Tercel with a 1.5 3E E engine in it. It failed the emissions part of state inspection here in Massachusetts recently with a HC level of 1.5, they were looking for 1.2 or better, the car has 160K. In the papers that the inspection station gave me, it listed possible causes for the failure, one of them was advanced ignition timing. Before I went for the inspection I changed the oil and gave it a complete tune up. I went home with the reject sticker and checked timing, it was way out, (+25) the hood sticker said +10 with diagnostic plug shorted which it was. I moved the distributor to get the +10 and took it for a ride, the car idled fine but when I went to drive it, it wouldnt get out of its own way. I put it back to where it was and the car ran like a champ again. My question is why wont my car run with the timing where Toyota wants it at

+10? Cam timing was also checked and was right. Thanks JT
Reply to
JTRacing
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Does the timing advance when set properly at idle and then revved? Check for vacuum at the distributor, check the mechanical advance.

Reply to
Ray O

The advance is electronic and when the jumper wire is removed from the diagnostic connector, the motor speed changes leading me to believe that the advance part of the distributor is working. John

Reply to
JTRacing

To be honest, I can't remember if the 1993 Tercel had electronic advance or not, however, when you remove the jumper wire from the diagnostic connector, it is normal for the motor speed to change, and ignition timing may or may not be advancing.

Having a diagnostic connector is not necessarily an indication that the car is equipped with ESA (electronic spark advance). A vehicle equipped with ESA will have a knock sensor and the part of the rotor that contacts the plug wire connectors in the distributor will have a large arc compared to one that does not have ESA. Also, an ESA distributor will not have any vacuum lines going to it and there will not be any centrifugal advance mechanism in the distributor.

It is very easy to verify whether timing is advancing or not. Connect the timing light and note timing at idle, then rev the engine and see if timing advances. For example, if it is at 10 degrees BTDC at idle, see if it goes to 12 or 15 or more degrees BTDC when you increase engine speed. If it does, then timing is advancing. If it does not, then timing is not advancing.

If your Tercel has the electronically controlled carburetor, then that is the likely cause of the problem.

Reply to
Ray O

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