I'm sure the question has been asked before (yes i searched) or maybe its just a stupid one no one has to ask. I'm going to be starting a tbi to tpi swap on my 350. when I picked up the intake, wiring and ecm today, the guys said I could use maf or speed density? I'm kinda new to fuel injection but I have a basic understanding of how each of these works. but which is better? can you run both? which does the car come with from the factory?

 

You say you picked up the ECM and wiring harness, which was it MAF or SD?
'85-'89 was MAF '90-'92 was SD. The ECM makes the determination.

 

perfect, that's exactly what I was looking for. the one I got was maf. is this preferred over speed density or should I find a new ecm?

 

MAF is easier to tune, especially if you have or plan to have mods to the engine. SD requires much more tuning, but is a simpler install for the intake hoses. Since you already have the MAF ECM, I would go that way.

 

alright, thanks!

 

I read the article about converting to MAP. Why does it go on about tuning? Can you just get an ECU and re-pin the harness if you just plan on keeping a stock car? Do you still need to change the memcal thing in the ECU?

 

Completely different setups .
You can rework the wiring harness but you need the correct ECM (MAP vs MAF ) and it's corresponding tune in order for everything to work correctly
Even though the 165 and 730 use identical looking memcals that will physically swap between the two ECM's ,
the tune and other things on the memcals are different

 

I know they're different setups, but I don't get why you can't just get a MAP ECU for a 350 and put it and the harness and whatever sensors are different in a 350 MAF car. Or am I just misunderstanding this?

 

Because there is no such thing
The MAP ECM is a '730 used on many different cars.
It is the tune on the memcal inside that determines what it is actually set up for ; 305 or 350 , auto or stick .
Many will sell a "350 ECM " when it has a 305 or V6 memcal in it
That can only be determined by reading the 4 letter code on the silver label inside the memcal.

 

So the 350 just stayed MAF? I'm really not getting this...