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Discussion Starter · #1 · (Edited)
just recently i've had an idle surging problem that i hadnt been able to pinpoint.....the idle just suddenly drops down to the 200's and comes back up.....about 1 out of 4 times when it does dive down, it stalls out......this has happened in idle in park/neutral and drive

here are some datalog pics of it

(the plot highlighted in yellow is the parameter being mapped to the numbers on the y-axis)

RPM:



STFTB1:



STFTB2:



LTFTB1:



LTFTB2:



O2 voltage B1:



O2 voltage B2:







i noticed that the LTFTB2 is almost always nearly at 1.10 when idling.....when driving it goes to 1.0 +/- 0.05

also, i noticed that the O2 dont switch nearly as fast as i thought they would be switching around the 0.5V mark.....they are bosch units that have roughly 50k on them......as you can see, they both tend to droop down to nearly 0V for about 1-2 seconds then come back up

i keep my LMAF impeccably clean, and the IAC is a new unit from autozone....i replaced it a while back when i thought the stocker was on its last legs......i also thought my new dual exhaust might have something do with it, in the form of an exhaust leak....but me and the exhaust guy went over the whole exhaust for about 30 min with the car running to make absolutely sure there was no leak before i left his shop....i also double checked it today to make sure non had developed....O2 sensors are tight

what sense can you guys make of this? ......any other parameters i need to datalog??
 
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