i like to know what involve into swaping a 98 post TB for a 99 no post TB on my L36 the only difference is the maf part number

you mean 00 postless right?

well 99 and up there are all the same

and i was asking this because some say you only need to unplug the batt for the PCM to learn new fuel curve is this true

You might get away with this...but the two different MAF sensors have different calibration curves, and you run the very real risk of going too lean for your PCM to compensate for.

The safe way to do this is with a tuner (or a vendor PCM, or at least an AFC or MAF translator device). And if you're going as far as a tuner (which I know you will, eventually), you might as well plan for a modded, possibly P&P'd, newer postless L67 TB

whit my aeroforce gauge what should i look for if im lean

my 02 is between 905 and 915

maf freq im at 8975 never in the 9000 range

You'll want to be looking out for KR, of course...but if you're going too lean for PCM compensation, your long term fuel trim (LTFT) will peg at +16.4
(All this is after fuel trims have re-learned, of course)

BTW, that'* your WOT O2 readings, right? That sounds about right to me for the overly rich factory PCM setting...you'd be able to get better WOT power if you could lean that out (to maybe 880-890) without inducing KR.

Also, your MAF frequency readings sound right to me for your stock '98 L36 TB with your current mods.

thank you andrew that very helpfull for me


and yes my 02 is at WOT

so if im rich from the factory whit the postless TB i should be ok

oh and which maf should i use in the postless TB the stock one or the one from my 98

that the TB i got form tj last night after cleaning

Wow Don, you cleaned that up very well.

Wrong. Your 'richness' is with a proper TB and MAF tuned for each other.

Switching to another set tuned for each other will still leave you rich. You need to change your mechanical setup in some manner (first priority) or tune it out (second priority).

You should use the MAF that comes with the new TB. The MAF on your current '98 TB may not fit in the new TB...and even if it does, it was engineered to take readings with the post in place; if you put it in the postless TB it may not produce consistent readings.