XFI Voltage

[karolko]

I have read all the other topics on Voltage on their XFI units, but i was wondering if anyone could post what type of voltages they are reading off their XFI.

I have done the casper bypass wiring, and i have checked the voltage at the battery and i have 14.55 volts when running but the XFI states that it is only seeing 13.0-13.2 volts when it is at idle (1000 rpm).

a couple of question i have to ask:

1) Is XFI taking the voltage reading from pin B18 (the main power wire)
2) What is everyone else running for voltage at idle. (factory wiring harness)
3) will voltage increase as rpm increases?
4) should i get a voltage booster?


thanks guys,

I want to have this rectified before i start tuning.

Adrian

 

[Turbo Loyd]

Timely subject as a file from a run two weeks ago, revealed the voltage near the end of a 1/4 mile run had lowered to 11.4 volts.

This prompted me to consider putting in a new rectifier bridge and regulator in the CS144 until I found past posts of voltages the XFI reads being low.

Last night after cleaning up grounds at the fire wall (relocated from the cylinder head), and power wires at the relocated fusible link connection block, the difference between the alternator and battery voltages was 14.7 at the alternator and 14.5 at the battery.

I made sure to clean the connectors on each end of the 8 gage wire from the alternator and add soldier tinning to these connectors to prevent future corrosion. This increased the voltage at the battery from 14.3 volts to 14.5.

The XFI read voltage increased from 12.7 to between 13.3 and 13.4 volts that does not change with RPM nor adding loads such as the headlights, heater blower on high or electric fan coming on.

After cleaning up the connections the VE table which was set for very little correction in closed loop now had -10% correction at idle. This goes to show how much the battery voltage affects the tuning of these cars. The voltage the XFI is reading may not correlate to the voltage at the fuel injectors. therefore the table that increases the injector pulse versus battery voltage is proving to be somewhat of a PITA.

At 13.4 volts the XFI main dashboard is showing a 2.4% positive battery voltage correction.

I'm thinking my next step may be to add a minimum 10 gage wire to supply the fuel injector circuit and main power circuit on the XFI through a relay, pulling these loads from the original wiring harness. Shall I use a fuse or relay on this circuit instead of a fusible link wire with the resistance that adds?

 

[LOT]

voltage

I have an adjustable voltage regulator set @ 14.8==my data shows 14.4-14.2 all the way down the track. I do have it hot wired per Casper instructions.

 

[DR BOOST]

hotwire the main power and the switched ign+ on the xfi. the xfi reads battery voltage off of the switched ign.

 

[HighPSI]

There are some software fixes for this. I'm just not sure when they will be released to the public. For Loyd, these fixes include a user defined voltage correction table. For Lot, there is a diferent voltage calculation for XFI that will cause it to read about 0.6 volt higher. There are several other "non-voltage" things in the works too. Stay tuned :biggrin:

 

[Turbo Loyd]

hotwire the main power and the switched ign+ on the xfi. the xfi reads battery voltage off of the switched ign.

Good point Surej, maybe it would be better to have a relay driven on by the switched ignition to power both the fuel injectors and XFI switched power. This way any adjustments to injector pulse the XFI makes due to battery variation may be relevant. I am running low impedance injectors so these may be adding quite a load themselves.

Suppose we can talk John Spina into making a plug and play harness to do this ?

Cal the news there are upgrades/changes in the XFI software is refreshing.

 

[johnplogii]

Cal, I have tried several times to get you on the phone to discuss this since I have bought three xfi's from you. I was under the impression I needed to run a hot wire to the xfi. I get 13.0 or so cold idle, my data logs show 12.5-13.0 throughout a run. I have 14.0 volts at the battery in the trunk & 14.3 at the alt. Will you please call me with your suggestion on what needs done if anything. Leaving for oklahoma/bowling green in a couple weeks & need time to get re-tuned if I have major voltage changes. You have my number on file, pm me if you don't. I also get the flashing check engine light while cranking sometimes & no start.

Thanks

John Plog

 

[HighPSI]

I'm sorry I missed your calls, John. Please text me if you don't get an answer. I'm calling now :redface:

Here's how I recommend wiring a "hot wire relay" to the XFI

Cut the wire going into XFI Pin B17
Attach the ecm side of the wire to Relay pin 87
Attach the harness side of the wire to Relay pin 85
Attach Relay pin 86 to ground
Attach Relay pin 30 to a good 12V constant power source preferably the positive battery terminal
I also cut XFI Pin B18 and attach the ecm side of the wire to Relay pin 30
I then tape up the harness side of that wire

 

[johnplogii]

Thanks for the fast phone call Cal.

 

[karolko]

I'm sorry I missed your calls, John. Please text me if you don't get an answer. I'm calling now :redface:

Here's how I recommend wiring a "hot wire relay" to the XFI

Cut the wire going into XFI Pin B17
Attach the ecm side of the wire to Relay pin 87
Attach the harness side of the wire to Relay pin 85
Attach Relay pin 86 to ground
Attach Relay pin 30 to a good 12V constant power source preferably the positive battery terminal
I also cut XFI Pin B18 and attach the ecm side of the wire to Relay pin 30
I then tape up the harness side of that wire

Would this also pretain to people running the caspers adapter harness or is this only for FAST harnesses? do i cut the wires between the Caspers harness and the XFI or before the caspers harness?

I would really like to get my hands on the software updates

Thanks for the responce Cal,

 

[HighPSI]

Would this also pretain to people running the caspers adapter harness or is this only for FAST harnesses? do i cut the wires between the Caspers harness and the XFI or before the caspers harness?

I would really like to get my hands on the software updates

Thanks for the responce Cal,

This ONLY appears to be a problem with adaptor harnesses. You would cut the adaptor harness wires.

I will make sure you get the updates, Adrian. Let me know if you need them before I see you and George

 

[karolko]

Awesome. Thanks Cal. I might try to contact you Monday next week about my part throttle stutter as i still have not started the car since we spoke last.

Adrian

 

[GNVenom]

My crystal ball tells me an electrical feed mod is in the horizon.

I believe the aging wiring (fuse panel, bulkhead, grounds, battery cables) adds to the voltage drop frustration.

You won't need a 10 gauge injector feed no matter which injectors you're running, but a good 12 gauge feed to a 30 amp relay might be the answer. This could help feed the ECU and injectors, so an additional relay might be the ticket.

Brainstorm time...

 

[HighPSI]

Thanks John!! It's great that you keep building products for these 20+ year old cars!

 

[Boost231]

I'm sorry I missed your calls, John. Please text me if you don't get an answer. I'm calling now :redface:

Here's how I recommend wiring a "hot wire relay" to the XFI

Cut the wire going into XFI Pin B17
Attach the ecm side of the wire to Relay pin 87
Attach the harness side of the wire to Relay pin 85
Attach Relay pin 86 to ground
Attach Relay pin 30 to a good 12V constant power source preferably the positive battery terminal
I also cut XFI Pin B18 and attach the ecm side of the wire to Relay pin 30
I then tape up the harness side of that wire

anyone who is having issues with voltage do what cal has posted above. he helped me wire mine up and now i have the proper voltage reading on the XFI. went from mid to high 12's on the xfi screen to 14.* volts

 

[karolko]

one last question. I already have the b18 pin bypassing the caspers harness, so only the b17 will be attached to this relay. Should i also have this thing fused with a 3 amp fuse? Directly wired? or 5 amp fuse?

Thanks guys

Adrian

 

[HighPSI]

I would put a fuse on the wire going to Pin 30

 

[karolko]

i guess i will go with a 3 amp seeing as B18 is also a 3 amp fuse. I cannot see it drawing more than that, could it?

 

[Turbo Loyd]

Another hot wire theory

I'm wondering as the ECM power is fed from the 10 amp ECM-IGN Fuse through terminal F on connector C437 right there near the ECM, this might be a good place to hot wire the key on power to the computer through the original harness.

How about pulling pin "F" from the computer side of terminal C437 and installing a pin connected to terminal 85 of a 30 amp relay, with terminal 86 grounded. With terminal 30 of the relay connected to the battery via a 12 gage wire with a fusible link, and terminal 87 of the relay connected to the wire pulled from pin 7 that feeds the key on power to the ECM, the accumulated losses in the original harness, from fusible links. ignition switch, and fuses with all the connectors between would be bypassed.

This should work on the theory the voltage losses are in the original Regal harness and not in Caspers adapter harness. This has the added benefit of hot wiring the CCCC module as well.

The fuel injector harness could be hot wired similarly at terminal C6 at the C100 terminal located under the wiper motor.

As you can see I really hate cutting into the wiring harnesses

 

[HighPSI]

That would work too. Sending you another PM