FAST XFI tuning question

[67ragtp]

Thanks John- I really layed the epoxy in there, my key and key way were a very nice snug fit so I dont think a lot of epoxy stayed around the shaft. It looks like it got pushed out the top and married the whole assy to the under side of the rotor mounting plate. Its pretty perminent now.

Rich

[TurboNova]

Originally Posted by wedged

I'm running sequential with no cam signal. I decided to do this to not have big spikes in pressure from batch fire. I have no idea if it makes a real difference.

Leaving the ECU in sequential mode with no cam signal with fire the injectors at random times and not where they need to run. The ECU will default to a random bank to bank mode.

[TurboNova]

For sequential on an Domestic EFI engine and XFI I usually use a MSD crank trigger 3/16" or Fast crank trigger 1/16" and mod a MSD billet distributor. It has a much better clean signal than any dual sync and is very easy to install.

The XIM coil on plug works great, I have changed over several of them on big block chevys and it really will wake up an engine. LS1 coils are the norm and work very well. It is a proven setup so there are no worries.

There was some good and bad info in this thread, I will try to be available as much as possible for any FAST, Accel or Big Stuff 3 tech or tuning questions.

[wedged]

Originally Posted by TurboNova

Leaving the ECU in sequential mode with no cam signal with fire the injectors at random times and not where they need to run. The ECU will default to a random bank to bank mode.

At what point does it default ? The LED's are always flashing sequentially when I look at the box, up to the point of RPM being too high to to see the sequence.

[67ragtp]

Brian,

can you tell me what kind of mods need to be done to the distributor to run sequential? How come know makes a cam sensor distributor so you dont have to mod one? If I converted it over to crank trigger will all the parameter in my timing table need to be changed and re-tuned?

Thanks for the info - Rich

[camcojb]

Originally Posted by 67ragtp

Brian,

can you tell me what kind of mods need to be done to the distributor to run sequential? How come know makes a cam sensor distributor so you dont have to mod one? If I converted it over to crank trigger will all the parameter in my timing table need to be changed and re-tuned?

Thanks for the info - Rich

that's the purpose of the dual synch distributors, one to give a spark signal and the second for the sequential fuel injection. Thing is, I have seen more failures and problems getting them set up right with the Accel and other dual synchs I think a standard MSD or similar dist and a crank trigger is the way to go.

You will not have to change the timing tables when adding the second signal, it would be used to have the injectors fire in firing order instead of batch or bank to bank firing. The crank signal would still be used for spark.

Changing to sequential may require minor tweaking to the tune, but nothing major if at all.

Jody

[GregWeld]

For about $900 you can ditch the Dual Sync distributor or cam signal altogether... by going to the Multiport EZ-EFI kit. That's what I'm doing.

Of course, that will be batch fired - but sequential is all about emissions over power or drivability.

As soon as my motor is done - I'll post up some engine dyno time from start up of this system to final. It should be interesting given the 8 stack EFI I'm running.

[67ragtp]

Jody - I think you may have mis understood me. I understand that the cam and crank signal come through the dual sync, which is what I currently run. My curiosity lies in the mods that are needed to a standard billet distributor to turn it into a cam sensor only, and why wouldnt fast sell it that way since it seems to be more common to have a crank triggers. Im thinking major surgery needs to be done to the reluctor wheel in order to trigger properly and what do they do with the advance weight and phasing. I dont really know whats involved there but it sounds like you would be hacking up a 300 dollar distributor right out of the box.
Rich

[TurboNova]

Originally Posted by wedged

At what point does it default ? The LED's are always flashing sequentially when I look at the box, up to the point of RPM being too high to to see the sequence.

With no cam sync, the engine does not know where #1 is so every time you start the engine it will look for a signal for #1 and may not quite get the firing order correct.

[TurboNova]

Originally Posted by 67ragtp

Brian,

can you tell me what kind of mods need to be done to the distributor to run sequential? How come know makes a cam sensor distributor so you dont have to mod one? If I converted it over to crank trigger will all the parameter in my timing table need to be changed and re-tuned?

Thanks for the info - Rich

Depending on how you want to run it there are several ways to accomplish sequential,

Fast Dual Sync
Accel Dual Sync
MSD really isn't set up right but will work
AEM 24x will work with the XIM COP box
GM has a Hall Effect Cam Sync that can be used.

I usually just buy a MSD billett standard mechanical distributor and about 30 mins have a good cam sync.

take off the distributor gear
pull the distributor shaft out
take off c-clip below the reluctor wheel
knock off the reluctor wheel and get rid of the roll pin holding it in place
break off 7 of the 8 teeth off the reluctor wheel any 7
drill and tap two 8-32 set screws opposite of each other in the reluctor wheel
put back together with out the roll pin in the reluctor wheel

Now you have an adjustable cam sync and can phase the rotor where you want to.
We have been doing cam syncs this way for at least 10 years now. Proven easy and better than a dual sync for high horsepower stuff.

Timing will not have to be changed, you will find that you will need less fuel in the VE table for sequential.