Saturn LS1 2000 misfire + more
 

Hi all
I have a 2000 Saturn LS1 2.2 and had the service engine soon light come on and had it checked at Advance parts. The codes showing on meter were, P0141, P0303, P0440, and P1621. I checked out the code meanings and found out that P0303 is a misfire on cylinder 3. I changed the plugs and boots and cleaned up all the connections. Took it for a test drive. SES light went out for the first 6 miles and then the intermittent misfire returned. Would not fixing the other code problems cause the misfire and/or are they related? The other code meanings are;

P0141 Oxygen sensor bank 1 sensor 2.
P0440 Evap emission system.
P1621 Power control module memory.

Also can any one tell me where the upstream sensor is on the LS1 2.2 is? I have found the downstream one. Searched the whole length of the exhaust pipe but can only find one sensor.

Help please, retired pensioner. Not much cash.

ya need a computer, the bad computer will mess everything up try a scrap yard and if ya find one it has to be from a car exactly like urs, if ur car has power locks the scrap car has to have power locks if ur car has manual windows the donor car has to have manual windows and so on that way there is no complications with body computer talking with engine computer

Thanks for that, I have since replaced the downstream O2 sensor with a new one bought on EBay for $33. Took out the old one no problem. When I put the 2 together the sensor part of the item was different. The new one had holes in the old one did not. I thought how could the old one sense the exhaust gasses without holes? Maybe it was the wrong one! So I ventured on and put the new one in. Guess what after about 50 miles no SES light and misfire gone. Yeeha, fingers are still crossed. I'll keep you all updated.
Happy miles
The Doctor.

Misfire
 

Alas, misfire is back. I am going to change the injector on the cylinder in my code. I have checked the ignition control module with a test lamp as shown here. It is not that.
:confused: