this is an 03 suburban 5.3L engine and ecu with an 03 express van 5.3L file on it.
did that because the powertrain is going into old school land cruiser and we didn't want to do the dbw.
all's good. running fine, fans-trans-etc. but there is a mystery rpm cut around 1500-1600. looking at the log though, it's not the injectors or the spark.
can anyone figure out what's making the rpm pulse like this? it's not tps either. you can see it go up and the STIT stops so it's out of idle control.
codes are mil and o2 heaters, which i'll fix, but shouldn't cause this.
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