quickSS

Before I hack up a GM Optispark distributor, I'd like to get some tips from anyone who has modifed theirs for use as the cam position sensor input to the FAST XFI ,(or any other aftermarket ECU).

FAST tech said that you can make your own (edit) cam position sensor by removing the opti slotted wheels and fabricating your own wheel with one slot at about 75 crank deg BTDC, (to be seen by the optical sensor).
Then you would make your own wiring from the output of the optical sensor and into the discrete cam signal input.

Have you done this? Did it work well?

Thanks,
Karl Ellwein
Ellwein Engines

Eric@Victory Racing

Yep, it works great. We created one that work with the BS3 unit.

Injuneer

Can't the FAST be programmed to run off the Opti pulse signals? I know several of the aftermarket ECU's, like my MoTeC can.

AdioSS

Karl, I'm 99% sure that JPG had this done to MiamiSpd. You might contact Roger and Jorge to get more info.

quickSS

Eric, thanks and that's good news. Can you describe your work a bit and the wiring. Thanks.

Did you just tape over the existing wheels and leave a slot at about 75deg BTDC crank (about 37deg cam/opti degrees)?

Did you get some thin metal and hole punch it and then drill for the slot?

Did you take the pin-out from the GM opti harness from the high resolution signal or the low? Which did you send to the XFI discrete cam sensor input?

Injuneer, FAST tech said no their XFI cannot cypher the pulses (like the GM PCM is programmed to do). They said run it in batch mode or get a cam position sensor.

Chest, I'll get with Roger and JPG thanks.

quickSS

I drew on an optispark optical disk what I think to be #1 piston at top dead center. Can I get a yea or nea please from anyone.

Photo link here:
http://www.ellweinengines.com/optisp...pticaldisk.jpg

thanks,
Karl Ellwein

quickSS

Be honest. Let me know if you think my mod (shown below) will work.
By the way, this is for the purpose of being able to run in sequential mode for use of 160lb/hr injectors on an F2 blower LT1-383, (to be able to idle).

I used aluminum tape (both sides) of GM optispark optical disk. I covered all the slots accept the existing slot that I found to be 35 to 45 cam degrees BTDC #1 piston (which would be 70 to 90 crank deg BTDC.)

Tested with a Digital volt meter on an engine stand motor and I got a pulse when #1 piston was around 80 deg BTDC on the crank. (just by eyeball). So on an engine stand it worked.

Seems like it should work and provide a pulse to the XFI discrete cam position input when #1 piston is at around 80deg BTDC so that sequential mode can be used. There are a bunch of wiring pin changes to do on the XFI opti harness and "hall effect connector" for this to work. The XFI tech told me what and where. (I don't have the harness...it's in Sweden and I'm trying to help the guy there with this set up). Basically you move the crank position sensor now from the opti to the crank trigger wheel on the crank and you provide the cam position via the 1x optical disc pulser in the opti--(that I just made). Move the GM opti harness pin A low res. pulse to pin C because pin C in the XFI harness is the discrete cam position sensor input. Also provide 12v to GM opti harness pin C (somehow) and also GM opti harness pin D needs ground (I think pin D needs to go to the XFI distributor ground pin input but not certain). He said loop pin A and B together and loop D and F together (whatever that means) on the hall effect connector harness. If I had that harness here I'd be able to visualize this and give clear instructions...sorry.

Photo of my protractor marked MSD opti disk,
http://www.ellweinengines.com/optisp...kmodified2.jpg
Leading edge of that slot is at 45 deg BTDC and trailing edge is at 35 deg

Photo of my modified GM opti disk,
http://www.ellweinengines.com/optisp...skmodified.jpg

All assembled and on a motor on a stand it seems to work. Hope it works with a running motor at high rpm and under load. The aluminum tape seems to be robust enough for now. If it melts under heat and flys apart then a fabricated/machined disc is needed.

jay_lt4

as you posted, i think heat will let the tape move at high rpm, but it will at least get ya started

ramermanz28

I run my car in SEFI vice Batch. The XFI was able to run SEFI with no modifications to my OPTI. I am however running all new harness' from FAST and a Delteq ignition with the XFI adapter harness from JC at Delteq. The only stock harness left is the body control harness. I was suprised when my car fired right up in SEFI. I think the XFI will interpret the signals using the stock ignition as well. I'm proof it works with the Delteq. Good luck and let me know if you need help. Rob.

Danno74Z

Hello everyone this is my first post/question/reply.

I have been following this thread with great interest and need to ask you guys a few questions. I did a search but never found what I was looking for. In regards to the FAST XFI, can I go LS1 COP on the LT1 engine? I want to eliminate the OPTI ignition altogether. I purchased a LT1 intake that was modified for a Gen1 distributor. I could go with a dual sync distributor and get both CAM and Crank signals but then I have an old style distributor arrangement which I don't want. I thought about using this for a cam sensor:

http://www.shopatron.com/product/pro...=MSD8514/424.0

I will use a crank wheel for the crank sensor input. Hopefully the number of teeth is adjustable in the FAST software or I may have to find a 24x wheel that the LS1 uses and make it work. With the opti distributor gone that will free up some space behind the dampener to attach the crank wheel. This should be doable. Now I have both crank and cam inputs to the FAST XFI for at least full sequential FI. I need the cam input for sure to locate cylinder #1 firing and the crank sensor to control the ignition coil firing and injector pulse. If I order the FAST XFI computer for the LS1 engine and use the OEM coil packs I think I should be good to go. I know the LS1 has a different firing order then the LT1 (7&4, 3&2) and this could put the kibosh on this whole thing. Can the firing order be altered through the XF1 software? If not can I just swap both coils and injectors leads and fake out the computer? Are there any FAST experts out there who can answer my questions?

THANKS,
Danno74Z

BIGCATPOWER

We Used A Msd Cam Sync. Pickup Pn# 2346 And We Used The Msd Small Base Dist. The Cam Sync. Install Is Not All That Bad. We Just Drilled And Taped The Front Timing Cover. We Used Blue Locktight To Seal It. The Msd Unit Is Small Enough To Fit Behind The Water Pump. Also You Might Want To Use A Small Dab Of 2 Part Epoxy To Hold The Magnet From Moving.