Stock ECM or Fast XFI???

[RmvBfrFlght]

I did not post a picture of a stock buick distributor or any other distributor for that matter. I did not specify stock/msd/other either but I guess I should have. My question was aimed toward the running the distributor set ups that have become increasingly popular in the TSM class...whatever set up that might be. The orginal distributor question is quoted here.

You are correct that no picture was posted. I have one on my system that I looked at and the brain blended it all together as part of the thread.

The question: from what I can tell the stock ECM will run with a stock Buick distributor. I rang-out the ECM circuitry, checked some scope plots of the ref & EST signals, nothing looks to be inverted or otherwise changed from the standard GM way of doing things. Even the chip that handles the EST loop in the ECM is the same as many other GM ECMs with distributors.

However, in stock form the cam signal is lost. Which means no SFI. ECM will default to batch fire mode and light the SES. It will run like this.

I considered trying it just to see if it would work. Although looking at the engine, not a lot of room to fit a distributor in there.

GM put cam sensors in a handful of Caddy's (don't recall which ones, look for SFI and a distributor). Can pull the cam sensor parts out of one and install into the Buick distributor. Then need to buffer the signal. Easiest method would be to use the stock CCCI module (no coils required).

Need +12, ground, cam signal to ECM, and the three wires from the module to the sensor. For the electronics types can put together a simple circuit to provide power and to buffer the sensor signal. And eliminate the CCCI module entirely. Hall effect sensors are easy to work with.

OTOH, for full out racing does SFI buy you anything? It probably does help at low engine speeds as it halves the injector firing rate which increases the PW, which makes it easier to control the fuel when running large injectors.

Once the engine speed gets up to the tire roasting level SFI doesn't provide much benefit. This is one of those things where trying it and seeing how it works pays off.

RemoveBeforeFlight

 

[HighPSI]

SFI helps when you are tuning individual cylinders. I'm not sure if you can do that with the stock ecm. I also don't know what kind of 2-step you will have with your setup. I know the wiring on our setup is real easy, just unplug the module and plug the conector in then plug the distributor into the cam sensor plug with the adaptor we also include. The only time you need a crimper is to hook up the ignition box (power, ground, coil, points, 2step). What distributor do you plan on running? An HEI is much larger than an MSD and things could get real tight.

 

[Nasty Wendy]

OTOH, for full out racing does SFI buy you anything? It probably does help at low engine speeds as it halves the injector firing rate which increases the PW, which makes it easier to control the fuel when running large injectors.

Once the engine speed gets up to the tire roasting level SFI doesn't provide much benefit. This is one of those things where trying it and seeing how it works pays off.

RemoveBeforeFlight

I will not under any foreseeable circumstance give up SFI. I have a Casper's Electronics 8 channel EGT unit that interfaces with XFI. The ability to add/trim fuel on each individual cylinder will be put to use when tuning my car. This is something else the stock ecm is not capable of even with the available piggybacks.

 

[BlackBandit]

I will not under any foreseeable circumstance give up SFI. I have a Casper's Electronics 8 channel EGT unit that interfaces with XFI. The ability to add/trim fuel on each individual cylinder will be put to use when tuning my car. This is something else the stock ecm is not capable of even with the available piggybacks.

Not THAT is a VERY legitimate advantage of XFI! I don't think it's a huge advantage at the lower power levels and the money could probably be spent better elsewhere (again at the lower power levels) but in an application where cost is less of a concern and every bit of available power is wanted that would definitely be an advantage. One could argue that the need for individual cylinder trimming could be negated by flow matching the injectors and having a intake setup that evenly distributes air, but at when trying to get ALL the power out the truth is you'll never get everything to flow evenly and individual trimming of cylinders would help.

 

[Jerryl]

...............Seriously guys, read my posts. I know FAST has it's place. I also know it's used allot when it's not NEEDED. That doesn't mean it's not nice to have, it just means the FAST isn't the only way to go fast and with the addition of WB corrections, and just the add ons in general it doesn't give the advantage it used to. I'll say it once more. If you need it, it's better. If you don't need it then it's a little like a chrome turbo cover, it looks good but you can go just as fast with the stock one.

Great summary!

 

[RmvBfrFlght]

I will not under any foreseeable circumstance give up SFI. I have a Casper's Electronics 8 channel EGT unit that interfaces with XFI. The ability to add/trim fuel on each individual cylinder will be put to use when tuning my car. This is something else the stock ecm is not capable of even with the available piggybacks.

I don't blame you for not wanting to give up the SFI. Running 60 #'ers on the street car it makes a difference.

I had thought you were interested in what it took to run a distributor in a TB. Which is why I replied. IIRC you recently inquired in another thread about pictures or something to do with putting a distributor in a TB. If not, my apologies.


As for individual injector trim (PW control), the stock ECM has that capability. It is also capable of having the injector opening time vs crank angle programmed. Among some other interesting features. Just need to get some of the chip guys to take advantage of it.

RemoveBeforeFlight

 

[Nasty Wendy]

Yes I did ask about running a distributor with AC in a previous thread. I appreciate your info too. My car (I have to check to see if I still have one its been so long since I've driven it) is going to be an On-Center street car with all the stock comfort items.

 

[BLACK6PACK]

XFI and the stock ECM both suck when compared to carburetors!! :biggrin: Just kidding.

 

[HighPSI]

As for individual injector trim (PW control), the stock ECM has that capability. It is also capable of having the injector opening time vs crank angle programmed. Among some other interesting features. Just need to get some of the chip guys to take advantage of it.

RemoveBeforeFlight

I am interested in the individual cylinder tuning of the stock ecu. Can you also tune individual timing? Once you determine what cylinders need fuel do you have to reburn a new chip or is this a user programable function of the chip? This is the first I have heard of somebody doing this. If you log EGT's I ASSume it is with an external device.

BTW: Who are you? I don't see any name, signature, or location.

 

[northerngn]

well i talked to cal today (of hartlineperformance)
definitely going with xfi
no more modding ecm for low imp injectors then additional modding for map input,wide band input afr tracking ect ect
if ya figure all that in xfi isn't that far out of reach...other than it will be a
1 time purchase with unlimited tuning possibilities
and with the support from hartline my transition to my new engine should be effortless
i am also looking forward to playing with e85 (cheap cheap cheap here in mn)...
i imagine from all the corn... 105 octane and no switching chips or fuel pressure b/s
man i cant wait
cal was great to chat with (as was his wife) and am looking forward to dealing with hartline performance again!!!

-dan

 

[RmvBfrFlght]

BTW: Who are you? I don't see any name, signature, or location.

Someday we will meet, Aloha.

RemoveBeforeFlight

 

[Underboost]

What?

I am interested in the individual cylinder tuning of the stock ecu. Can you also tune individual timing?

+1

That would be nice! I already have my EGT bungs drilled in the headers. :biggrin:

 

[Eric Stage I]

I can do individual fuel correction in the chip. It's not a user adjustable feature (at this time). I would need the EGT data, and add/subtract pulsewidth from the injectors in question, then reburn the chip. No individual timing though.

 

[HighPSI]

cal was great to chat with (as was his wife) and am looking forward to dealing with hartline performance again!!!

-dan

Thanks for the kind words, Dan. Now start prepping the car for E-85

Someday we will meet, Aloha.

RemoveBeforeFlight

Perhaps, but I guess I'll never know even when we do meet...Mystery Man.

 

[HighPSI]

I can do individual fuel correction in the chip. It's not a user adjustable feature (at this time). I would need the EGT data, and add/subtract pulsewidth from the injectors in question, then reburn the chip. No individual timing though.

This is great news, Eric. You really seem to have this chip stuff sorted out. We have, and will continue to, recommend you to our customers needing a chip. Is the IC correction straight across the board or does it require other parameters before it starts? The reason I ask, is because I have seen IC correction vary with diferent rpm's and boost levels.

 

[WSLN 6]

I have always used Erics chips as well, and they can't be beat on a high 10 second weekend warrior. That being said, the faster you get, the more the extra resolution of a FAST system can be utilized.
Maybe you can run the 100 yard dash quickly in rubber boots, but it would probably be less clumsy with a pair of Nike's on......JMO

 

[Eric Stage I]

I've only tested it as a set pulsewidth offset across the board. However, I realize that you would not want the same offset at idle as you would at say 7000rpm. I would probably have an RPM cutoff so that no correction would be applied below a certain RPM. I don't have much room in the chip to make it more elegant than that. The XFI user interface makes it much easier to play with on the fly.