Replaced timing belt now poor gas mileage and engine misses

CRCSHANNON

MEMBER
1993 TOYOTA TERCEL

1993 Toyota Tercel with fuel injection. I changed the timing belt and after my gas mileage went to 10 miles per gallon from 40 mph. I did every thing the book said from my alignment marks on the cam #1 cylinder up, distributor pointing to #1, and timing mark on the mark. It's drive-able but misses more than before.I have torn it down twice again to make sure of the timing marks were right. My engine light came on once saying I had a bad Oxygen sensor. So I replaced it, but didn't help. It smokes more than it did, some smoke from leaking valve seals. Any help will be appreciated. Chuck

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

So if you had a code for an o2 sensor, did the code return? If the code did not return then you are not "throwing parts" at that issue but the sensor did in fact resolve it, it just did not fix the smoking and running poorly issue.

I suspect you potentially have a couple issues. The smoking issue may be some unburned fuel and oil from the valve seals. However, if you have verified the timing marks are set up properly then we need to check your ignition timing because this will cause the same thing.

I attached the procedure for review. Please reach out with questions. Thanks

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