Any true differences in EFI units?
 

I'm searching for an upgraded EFI unit. The one I currently have is a DOS based ACCEL unit. The more I search I wonder if there is actually any difference in the units themselves? (ms3, xdi, sds, ACCEL etc etc) how is it that some are better than others? in what way? I read about some being easier to tune than others, but I wonder....wont the parameters be the same? I don't want to run a new wire harness Ideally, I want to just be able to unplug my old unit and plug in the newer one (some retrofitting is ok). I am an amateur when it comes to this, but I would like to be able to tune it myself or for it to come pre-tuned?

My car is a 1977 911 with a 3.3 TT (25psi) / G50.


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There's variance in processor speeds and granularity in fuel/ignition maps between brands and models AFAIK.

You run 1.7 bar of boost?!?!

I bet that's more 1.1 BAR, if its an old ecu it may include atmospheric pressure.

New ecus will also have some more user-friendly graphing, adjustments and support in terms of other people able to provide troubleshooting or base maps.

You shouldnt have to switch sensors either if you pick a modern ECU with sensor-learning which is a fairly basic feature nowadays.

I like my Adaptronics: Adaptronic - Energise Your Engine!

Thanks for the info, so if there is a difference in processor speeds.....what processor should I be looking for? I'm glad to hear that I don't need to switch sensors...I'm guessing I will need to find a way to adapt the current adapter or plug into the newer unit?? I'm going to start by reaching out to Accel to see if their newer units have the same plug fitment.

Baker I wouldn't limit yourself to the same harness. Just use the location of the old one as a road map for the new one.

There are many-many standalones to choose from but unless you can tune yourself or willing to learn it or get to know other makes, you should choose the ECU that your nearest tuner can tune.

There is no use of whatever ECU if it is not tuned properly.

If money would not be object, I would choose Pectel SQ6 or something similar. Unfortunately it is so I'm staying with VEMS.

New ECU's can control so many things, it's ridiculous....everything is configurable, and as mentioned above, faster CPU means finer control of everything. A computer from the 70's is essentially the same as todays supercomputers, they all process nothing more than 1's and 0's...but....

Re which CPU, AFAIK, ECU vendors don't state which uP they use...it could be anything from off the shelf Intel, to ARM, to custom chips.

Completely agree with above comment about using whatever your trusted tuning shop is familiar with, or a brand where you can source consistent and reliable community help. I'm not familiar with it, but I believe Megasquirt has quite a following on various fora, if you want to go the DIY route with mapping. I'm going with MBE, who are quite prevalent here in the UK, simply because one of my best mates is an absolute genius with mapping it (he jointly developes a lot of the code with MBE)...it's all waaaay beyond my capabilities I'm afraid.

IIRC, MegaSquirt uses Motorola processors.