Pulled my 50mm PMO's from my 3.6L 911SC and have purchased the full TWM individual throttle body fuel injection setup.

Currently I have a Electromotive XDi crank-fire, twin plug setup.

At this point I can go with a simple MegaSquirt (which I have zero experience with) or or remove the XDi box, and install the TEC3 box (which does both fuel and ignition).

The TEC3 is about $2k. The MegaSquirt is about $500


Which way to go?


TonyG

 

I'm running Megasquirt. It can handle both fuel injection and ignition like the TEC3. $500 sounds a little steep for even the megasquirt II. You may be including the relay board and some other odds and ends, but you don't have to use a relay board, I don't.

I don't have any experience with the TEC3. I would guess the major non-technical difference is that you'll be on your own as far as configuring and testing with the Megaqsquirt unit. TEC3 is a comercial product and you should be able to find someone out there to help you with the configuration and tuning if you need to. Regardless, I would strongly suggest you include a wide band O2 sensor with your installation, provides much better feedback on your AFR and additional tuning flexability as you can program the EFI controller with a richer target AFR for better drivability and HP.

Good luck with your installation.

Regards,

Mac

 

911mac

Thanks for the reply.

My biggest problem is that I've emailed some of the vendors that sell assembled units, with questions, but nobody has responded.

I need questions answered like:

Should I dump the XDi and have the MegaSquirt control both fuel and ignition, or keep the XDi and have the MegaSquirt only for fuel? Why or why not?

Can I run two wide-band 02 sensors (one for each bank)? Does the MegaSquirt have a "learn function" to get the maps close?

On and on.... Questions, but nobody to ask.

TonyG

 

Tony,

Your best source of information on Megasquirt II is here:
http://www.megasquirt.info/ms2/

It explains all the various ignition options. If I were you, I'd run off your existing ignition until you get the fuel injection running to your liking. Then you can look at what's required to let Megasquirt control the ignition and decide if you should stay with your existing ignition or not.

The Megasquirt configuration and tuning software is called Megatune, it has a feature you can configure and turn on called autotune. It will modify the VE table entries based on the O2 sensor readings. You just hookup your laptop, turn it on, and drive around varying your speed and load. If you don't have a wide band O2 sensor, it's not advisable to tune WOT or heavy load/highrer RPM situations this way.

Megasquirt is only setup to use a single O2 sensor, you could come up with something to let you switch between two sensors. Maybe have a gauge that
shows you the AFR each is reading.

-Mac

 

just a noob question, can the motronic be reprogram to handle indiv. TB like the TWM.

 

HMD,
The motronic can be reprogrammed but it takes specialized knowledge and equipment to do it. Engine management systems like TEC3 and Megasquirt can be reprogrammed with a laptop.

I'm not sure a switch from stock to ITBs would necessitate reprogramming the motronic. Probably the biggest issue would be connecting the throttle position sensor, manifold air pressure sensor, and manifold temperature sensor to the ITBs.

Regards,

Mac

 

"can the motronic be reprogram to handle indiv. TB like the TWM" - hmd -

No!!

"The motronic can be reprogrammed but it takes specialized knowledge and equipment to do it." - 911mac -

Not correct! Not only would reprogramming (at the microcode level & not just
maps) but a MAJOR electronic redesign of the Motronic circuits would be required..

 

911mac

>>>Probably the biggest issue would be connecting the throttle position sensor, manifold air pressure sensor, and manifold temperature sensor to the ITBs.<<<

The TWM throttle bodies came equipped with the TPS, and a one (1) port on each bank, which connect to each runner, for the MAP sensor. The temp sensor is the oil temp sensor (not the stock oil temp sensor... but a seperate 2nd oil temp sensor).

I think the biggest problem would be that the factory ECU doesn't use a real TPS switch.

The MAP signal could be adapted and fed in (MAP conversions have been done many times with the factory ECU), in a corrected format, as the factory air meter is.

I'm sure it can be done... but is it really worth it considering that it's a very old system with major limitations?

TonyG

 

Tony,

That's a great explanation. I have seen many Motec ITB system and I am sure the Autronic autotune would be great as well, they are all great Aussie product But if you are looking at nofrills ECU the MicroTech could be the go, there have been some MicroTech with ITB application on the 911.

 

I should have my microtech/jenvey itb set up running in about 4-6 weeks. I can update my thoughts on it at that time.

Cheers

 

I am running TWM's with Megasquirt II on my 83SC and it runs great, currently I use the MS just for fuel as I am running the OEM distributor but in the future I will add Ford EDIS and will probably have the MS control it but the EDIS can be run stand alone.