Tough 3.6L conversion question

[mnmasotto]

I recently purchased a 1995 3.6L motor which I am installing in my 1987 Carrera. The motor currently has a 964 AFM, 964 ECU and possibly a few other small 964 odds and ends to make the AFM work. I know you are wondering why?????

The motor initially had 50 PMO carbs. Prior owner complained of terrible gas milage, poor driveability and recurrent spark plug fouling. After two years with the carbs he wanted to reinstall OEM fuel injection. Apparently, the original 1995 parts were no longer available and his motor builder had a spare 964 AFM and ECU lying around. Hence, my current setup. I am told the car runs fine with the current setup but a stock MAF would work better.

What do I need to replace the 964 AFM (air flow meter) with a stock 993 MAF? Can I just buy a new 993 MAF, wire it up to the existing wiring harness and change to a 1995 chip? Or is there more to this?

Thanks for the help in advance.

[Don Plumley]

AFIK, you can't use a 993 MAF with a 964 ECU.

[mnmasotto]

On my 3.2L Carrera motor I switched from a AFM to a MAF. All I had to do was install a new chip in the stock Motronics ECU box. The new chip (MAF chip) recognized the different voltage output scale of the MAF.

Why can't I do the same with this motor. Put a stock 993 MAF in place of the 964 AFM and install a 1995 993 chip which is compatible with/recognizes the voltage output of the new air metering device.

[Bill Verburg]

964 DME and 993DME are not interchangeable
964 DME pinout


993 DME pinout


There are kits to allow use of MAF on 964s, Vitesse amd Cartronic both jhave popular kits.

In your shoes I'd also consider Motec

[mnmasotto]

For the price, how about Electromotive? I know you get what you pay for, but can Motec really be that much better for a street car? Besides who sells Motec locally?

[DW SD]

Why not get the 993 engine harness, ECU and MAF and sell off the 964 parts?

If you buy right, the delta can't be too great.

In fact, if you shop with some parts dismantlers, maybe you can trade $500 + the parts you have for what you need.

Doug

[ischmitz]

Every time you change the transfer function of the air metering device (barn door flapper, hot wire MAF, etc.) the calibration table inside the motronic needs to be modified accordingly.

Your prior post implies the chip in your 3.2 "recognizes" the different setups. This is not exactly true. The chip or the Motronic is not smart enough to tell two different devices apart. A better statement would be the chip is "tuned" for a particular setup. Once you change the air flow meter you need to change the map in the chip.

It is my understanding that the barn door has a linear response function while the hot wire sensors are logarithmic. So they are not interchangeable. Futhermore the main difference between the 993 and the 964 DME is the spark circuit. The 964 has one chanel for both spark circuits while the 993 has two chanels. Also the throttle position sensing is different. A 964 has switches for idle and WOT. The 993 has a throttle position potentiometer. And as Bill said the pin-outs are very different.

I guess you could have someone custom-tune your 964 chip to work with a 993 MAF but the effort (time, $$$) would certainly exceed the cost of a straight swap. As other suggested either stick with the 964 setup or try to get a complete intake with wiring harness and 993 DME. Just make sure you get the right DME type. There are several 993 versions (vario-ram, non-varioram, OBD-II). You want the OBD-I non-varioram 55 pin version.

Cheers,
Ingo

[Cooper911SC]

I think the MOTEC Importer is in Garden Grove or Fountain Valley...I put a clear bra on his 997 last year.

[rsscotty]

This is a dyno sheet using Split Second MAF system, Steve Wong custom chip and upgraded injectors. We have done two in the last couple months with great results. Customer support from Split Second and Steve Wong is 1st class.

[Fast951]

As others said it already. The 993 MAF is not a direct plug in. Converting to a MAF has plenty of benefits, just make sure you get a genuine MAF code on the chip. Getting a MAF with a signal massager to make the MAF look like the AFM to the DME is not a good move..
You can email me directly if you need help.

[scarceller]

Does anyone know the pinout for the 993 MAF?

The MAF has 4 pins and I'd like to know what each pin is for:

Power, ground, signal and signal ground I suspect.

I have a 993 MAF and am looking to use it in a conversion project I'm working on.

Need this chart filled out

Pin # signal
-------------------------
1 ??
2 ??
3 ??
4 ??

Thanks in advance for anyone who can help.

[gtc]

The 964 and 3.2 barn door air flow meters are pretty much the same right? So wouldn't it stand to reason that you could use one of the 3.2 MAF kits on your 3.6?
I guess the big issue there is that they're several times the price of the 993 MAF sensor.

[Bill Verburg]

1) chassis ground in the passenger compartment
2) pin7 on the DME
3) pin 7 on relay 53 only used of cars equipped w/ immobilizer
4) pin 26 ground on the DME

[scarceller]

Bill,

1 - main ground
2 - Signal out 0-5vdc
3 - 12vdc? is that correct
4 - DME signal ground

I'm assuming 12vdc on pin 3.

I'm actually working on using a bosch Hot Film MAF as well as Standard Mustang 5.0L Hot Wire MAF as a drop in replacement in the 84-89 3.2L cars. I have already re-written much of the program code in the chip (not just the maps) to do this. I have completely re-written the Air Flow model in the chip program to properly use the much more accurate MAF signal. All I'll say is you really can't simply put a MAF in place of a AFM without re-writing the code. The MAF is just a much different device than an AFM.

I'm a ways away from a final product but well on track to doing a proper conversion.

Thanks for the pin outs.

Originally Posted by Bill Verburg

1) chassis ground in the passenger compartment
2) pin7 on the DME
3) pin 7 on relay 53 only used of cars equipped w/ immobilizer
4) pin 26 ground on the DME