BackInBlackGP

So, a random though pops into my head today...

My 1986 2.8 Firebird has a MAF sensor, but no MAP sensor.

My 1994 3100 Grand Prix has a MAP sensor, but no MAF sensor.

My 1997 3800 Grand Prix has BOTH a MAP sensor and MAF sensor.


Since the 2.8 and the 3.1 are similar engines, could a conversion be done to remove the 3-wire MAF sensor unit, and replace it with a MAP sensor, and do any electrical conversions to get it to work properly with the ECM? Obviously there would need to be a customization of the intake manifold to accomodate the sensor, but that's the easy part...

What are your thoughts?

Doward

You have to swap ecu's to a SD computer.

You can repin the MAF connector to run to a map.

Intake mod? Just run a vacuum line to the MAP sensor, you're done

BackInBlackGP

What is "SD", and is the conversion worth it? Can I recycle my upgraded ECM chip, or do I need to pick up a new one?

TomP

SD = Speed Density = the name given to the way air flow is determined when using a MAP sensor.

This was actually done on gen II FWD 2.8's with the 5-pin "combination" MAF + MAT sensor. I think there was also a service bulletin out for the 2.8 f-bodies, too. Anyway, the MAF's commonly broke, as we know. GM released a "fix" that involved a new computer chip and a MAP sensor. The MAF relay was disconnected, but the wires going to the MAF were still plugged in to allow the MAT to still function. (5 wire MAF = 3 wires for MAF, 2 for MAT).

The MAP got tagged in at the connector for the MAF relay, and wired to power and ground, and had a vac line run to it.

Now that was for the Gen II 2.8's (front wheel drive). Might have to do some research to determine if the same applied to a Gen I 2.8 in an f-body.

1991tealRSt-topGuy

if your not making any serious, and i mean serious power, its not worth it

you have to re-pin to a new ECM connector that will fit a 730 ECM

its usually done to eliminate the MAF sensor (because its a restriction) on hi power engines

the only reason i could see to warrant this being done in this situation, is to eliminate the MAF sensor because it can be troublesome

the 730 also has a faster baud rate than the MAF ECM

BackInBlackGP

I hope not! It's still only a 2.8...

Atually, I wanted to get it out of my way on the intake. The inlet side is not parallel with the outlet side, so it makes my custom intake look a little silly...

Well, never mind then. It was just a thought. Thanks for the info!

TomP

Teal, do you know if the FWD Gen II's used the same ECM as our Gen I 2.8's? That car of my dad's had a sticker on the driver's side shock tower. It mentioned a speed density conversion, said the chip was replaced, and gave a service bulletin # to "read before servicing this car"- it didn't mention that the computer was replaced. I wish I had thought to write that damned # down; the car's a few years gone already.

If the ECM's were the same on Gen II FWD a-bodies and Gen I RWD f-bodies, then the ECM wouldn't have to be changed for an SD conversion. In fact... that Gen II 2.8 must've had a CSI, right? The sticker didn't mention anything about the CSI removed.

This might be good info for the "I want a turbo" guys...

82-T/A [Work]

I don't know WHY you'd want to get rid of a MAF system for a Speed Density system. My 87 Fiero uses speed density. Pontiac LOVES Speed Density systems, and they use that in any application that they can get away with where it doesn't interfere with production of another vehicle.

The SD on my car uses the Vehicle Speed Sensor, in conjunction with a MAT sensor, and a MAP sensor along with the TPS of course.


However, a MAF system is much easier to deal with when modifying an engine. Seriously.. it can measure the amount of air flow comming into the engine, and therefore convince the computer to send more fuel MUCH easier than an SD system can. MANY Fiero owners try to convert to a MAF system from a 3.1 Camaro / Firebird.

If it's broken, just fix it.

1991tealRSt-topGuy

there is a fine line between (easy to tune MAF) and (less restrictive) Speed Density

as an example, somebody who might stick with a MAF sensor: car is daily driven, and the mods that are done to it are not too extreme, say like a slightly bigger cam and a little headwork AT THE MOST

those who convert to Speed Density usually have a need for more air and in turn, they take advantage of every possiblilty to free the air path; this person prolly has hi-performance heads, worked bottom end, and a large cam........cars not really a daily driver, its meant for performance

1991tealRSt-topGuy

Tom, i'm honestly not sure, because i stopped following the V6 thing awhile ago

part of me wants to say "yes" that the gen II fwd cars use the 730 ECM

another part of me wants to say "no" because they use DIS and i am not sure if that is supported by the 730 ECM

although i am learning more towards "yes" the gen II FWD cars use the 730 Speed Density ECM