Aftermarket Fuel Injection 1

[thruthefence]

Does anyone have experience with after market Fuel injection systems, " Megasquirt " in particular. There is a huge presence on the web about the system, but is seems very disorganized. Having 'inherited' a system, ( basically a box of components ) when I purchased a rebuild project, I'm wondering if I should not acquire the oem harness & ecu, rather then reinvent the wheel. The engine is a 4AG 20 valve Toyota "silvertop". I am not as interested in wringing the last bit of power out of the engine, as I am in driveability.
Thanks in advance for any insight.

 

[Warmington]

Why do you say that the OEM idle control would even need say a 12x12 mapped table which is only a tiny part of the MS software?

 

[NormPeterson]

"There are software functins in an OEM system that simply do not exist in the world of MS etc, not only because of the complexity involved but also because the lack of knowledge/ability for a backstreet tuner to calibrate them."

Could you perhaps list a few of these functions? Aside from likely differences in map resolution and naturally the trouble codes, I'd like to bounce it off DFI's capabilities (supposedly that system was developed by an ex-GM engineer). I do know of one function in the DFI that has not direct OE counterpart, but which could probably be used to drive a specific OEM intake system feature (and may have been developed from that).


Norm

 

[thruthefence]

For the record, I mean no disrespect to those who have un-raveled the megasquirt ECU. I have nothing but admiration for those who can sift through the ( to me, anyway ) huge volume of data that's out there. Perhaps I didn't look in the correct place, but among the scores (maybe hundreds) of websites I perused in the last 6 months, but I found not one 'semi turn key' fuel & ignition map for my particular engine. For every success story that I found, there was another guy posting photos of his burnt & holed pistons.For every user that's " fighting a little rough idle", there's another guy that has 24" flames out his exhaust when getting off the throttle. And 'pulling the trigger' on this project literally meant no turning back. As I said before, you have to cannibalize the the existing engine harness & connectors to wire the system up, & they (harnesses & connectors) are very scarce in this country if you have to start over. Geeze, I guess I might as well admit it, I'm getting OLD!! Thanks again, everyone for your views.

 

[BrianPetersen]

Both sides of this discussion have valid arguments and both sides seem to be not grasping the points made by the other.

There ARE things in OEM EFI programming which are neither present (nor, in many cases, necessary) in aftermarket EFI programming: OBD-II compatibility, very fine closed-loop programming for emission control purposes, redundant fail-safe programming to allow limp-home capability in case of certain failures, etc.

For a bone stock engine that is fairly recent production, no argument that there is really no substitute for the OEM programming.

BUT ... Take that same engine, change the camshaft, change the pistons, put different cylinder heads on it, maybe throw a turbo on there, and generally make big, big changes to the intake and exhaust systems so that the end result shares pretty much nothing other than its bore-centre dimensions with the original design, and now tell me how far that OEM ECU is going to get you. (Answer: Nowhere.) For a situation like this, the OEM ECU on its own is simply not going to get the job done.

Personally, in a racing application that "really mattered", I think I'd lean more towards something like Motec rather than Megasquirt for its additional functionality, but the simpler systems still have their place. Racing applications don't have to meet OBD-II ...

 

[patdaly]

Another thing that has not been beat to death here is the ability to control much larger injectors with the higher end aftermarket ECM's.

Perhaps the OEMs have stepped up to the plate since the late 90's, however at that time I could find none that would allow a reasonable idle quality with 96 Lb injectors.

Granted the OP's question was with a less than sophisticated unit such as the sequential FAST unit I run or a Motec, but I still fail to see how anyone who can tune a carb and set an ignition curve would have issues with tuning an ECM appropriately matched to an Injector. ( I.E. matching a 300 dollar Megasquirt to a set of 96 Lb injectors )

In case anyone might be interested in one of the newer aftermarket systems out there, one that should open peoples eyes, here is a link.

http://www.mastmotorsports.com/proto90ecm_main.php

 

[duster360]

I've installed and/or programmed several different after-market EFI systems. AEM, Holley Commander 950, Accel DFI, Performance Electronics, Megasquirt, ect. Now I'm starting to dable into my first OEM ecu the Mopar NGC-3. Let me tell you, mattsooty , dead on, there's no comparison between the aftermarkets and the OEM.

With that said, I'd have agree most with franzh acessment though. To paraphrase: OEM are unmatched in drivabilty,emissions, durability, ect. Most aftermarket systems can get you 95% of the way there with good programming, enough so that the end user barly notices any difference.

Although the aftermarket is at best only 95% of the oem, it will also be 95% better than the carburator it usually replaces.

To thruthefence; I've never cared for the Megasquirt and usually advise against it in favor of the ADDED VALUE of other aftermartket systems. It will "work" no doubt, but, imo far too much depends on the assembler and end user. I believe many first time efi users are enticed by the low purchase price, but imo its a bait and switch. You get no wiring, no enclosure, poor non-automotive spec headers, poorly placed board mounted MAP sensor, no other sensors included at all, little no vibe proctection, ect. Even most aftermarket ecu's go through some sort of validation testing for vibration, esd, thermal, ect,,, your MS unit is just a mystery. If you Add the value of all the NEW sensors, wire harnessing, ecu enclosure, and quality testing of any off the shelf aftermarket EFI systme INTO the price of a MS, it could be an EASY $1000-$1500 EXTRA!

Since a decent Accel DFI or Holley C-950 sytem is only $1000-$1500 brand new(usually including a new fuel pump too), the added value does NOT favor a MegaSquirt.

 

[JonKBmw]

I don't want to seem partial, but I love the MS platform. I run a modern 24v DOHC BMW engine turbocharged on these units and I love it. I have built over 30 - 35 units for about 20 BMWs and the remainder for other cars. Its not for everyone though. For people who don't know much about electronics let alone tuning, its definitely not the most wise choice.

HOWEVER

Let me link you guys to something that might change your opinions! Well, two things really. First and foremost:

http://www.megamanual.com/seq/

You must click that. It is promised to stand the aftermarket ECU world on end.

Secondly, click this one:

http://www.megamanual.com/357/

The first is a VERY compact fully sequential surface mount version known as MS2 Sequencer - sequential fuel and sequential ignition control.

The second is a current (and what powers my car) version called MS 3.57 - its a surface mount version of the normal 3.0 boards. You can run MS1 or MS2 CPUs on it. The improvement though is that its SMD, so no issues with thru-hole construction!