Hi, I have 2001 LS V8, when first started in the morning, after rpm drops from 1500 to about 900 the car starts to idle rough like misfire or like when doing KOER test for 5 sec and then rpm goes up to 1000 and everything is smooth. Also, I tried monitoring LFTR when car is hot at idle: bank 1 is about +13, bank 2 is +3, SFTR look OK for both banks bouncing from -1 to +5. At 2000rpm long trim bank 1 goes to +9 bank 2 stays at+3. Question: is this normal? Is it possible to have vacuum leak just on bank 1? I tried spraying starting fluid didn't see any change. Also, i just replaced upstream O2 sensors with Bosch, but cat monitors look original with 105k miles, do they have any effect on fuel trims. Thanks.
Rough idle at warmnup and fuel trim.
- Thread starter devilsy2k
- Start date
Thank you for your response. The car had bad tensioner on bank 2 and stretched chain that was making noise. I replaced bank 1 and 2 tensioner and bank 2 chain. Also had misfires under load with no codes, replaced with new coils and running very smooth under all conditions except for 5 sec when warming up. It has no codes currently. If it's bad injector it could be that it's getting unwanted fuel? That's a possibility. I haven't monitored it during start up yet, what it's doing when it's running g rought? What should I look after? It might be a coincidence but it started about the time I replaced O2 sensors. What pids should I monitor O2 sensors, what voltage they should be at? Thank you.