<Posted this in diagnostic forum too>

I have this problem with my car. Sometimes after it warms up, it will buck or hesistate when I would take off in first. ONce it got to 2000 RPM it would clear up and move on.

Also, high load low rpm situations I would get the same thing.

Friend of mine scanned it with datamaster. NOticed that once it got to closed loop it would go back to open loop for a sec then to closed loop. It would cycle like this the whole time. Also noticed the 02s were not scanning from 100 to 900 like they usually do at idle. Also we took it for a ride and it acted up again going up a small hill in 1st or 2nd (I forget) and that is in the log and shows the sterms dip to around 70 when it started to buck.

Put some 02s he had in that he knew where good. THe scan with the new ones in still show it swapping back and forth from open to closed loop. THe 02s seem to sacn more too.

Guess I was wondering since the sterms and lterms are so low could it be an opti problem? But I would think with the 02s looking only for oxygen, that if I had some missfires from a bad opti it would show the car runing lean and try to add fuel with higher sterms and lterms, not taking fuel away.

BTW, car seems to act fine above 2000 rpm, as you can see in the 2nd file of us driving around.

THis started about two days after I got my exhuast welded up and cut out put in. Which was about 1.5 weeks after we put heads/headers/rr on. Dont know if there is any correlation there.

Any help would be appreciated.

car idling


driving car around

With new 02s on and reset computer

Thanks

Jason