Min. cranking voltage with XFI

[tttype]

Car used to run fine warm, but I never did get cold starts dialed in to run smooth, until engine warmed up.
Car has sat for a month & now it wont start.

Noticed some of the electric aftermarket gauges are rebooting during crankings, so watched voltage during cranking & it drops down to 9.4V.
Will XFI be ok with that voltage ?

Engine sputters & tries to start , but thats it.

 

[Boost231]

nope. you need more power. get the battery of a charger or get a tender for when the car sits.

 

[Chevota]

Car used to run fine warm, but I never did get cold starts dialed in to run smooth, until engine warmed up.
Car has sat for a month & now it wont start.

Noticed some of the electric aftermarket gauges are rebooting during crankings, so watched voltage during cranking & it drops down to 9.4V.
Will XFI be ok with that voltage ?

Engine sputters & tries to start , but thats it.

In short, no. You need 12 volts+. If you're using Casper's adapter harness you may want to "hotwire" your XFI to eliminate the problem.

 

[Boost231]

+1. still need to look into the best and cleanest way of doing this

 

[BADDGUY6]

In short, no. You need 12 volts+. If you're using Casper's adapter harness you may want to "hotwire" your XFI to eliminate the problem.

How do you "hotwire" the XFI?

 

[Chevota]

How do you "hotwire" the XFI?

Connect XFI pin b18 to a hot source from the battery, bypassing the wire from the Caspers adapter completely. Or, you can be brave and just use a "tap in" type connector.

 

[HighPSI]

As long as it's not dropping below 9 volts and going into "flash mode" it should still start.

 

[tttype]

I am using a Caspers PnP harness.
May check the voltage going into the PnP box during cranking .
If its higher than the XFI reads , than hotwiring the XFI may be the way to go.

Have the ECU hidden under a kick panel now, so cant say if any lights are flashing during cranking.
Another thing to check.

 

[tttype]

Just checked & have had the XFI "hotwired" all along. So thats done.

Engine fires quickly , but dies after about 1/2 second.
Its very consistant, fires fast but dies quickly every time.

Since XFI install, car never cold started that well, but did run well warm.

Possibly corrupted something while working on improving cold start.

Anything obvious that will shut it down right after it fires ?

 

[Chuck Leeper]

"Anything obvious that will shut it down right after it fires ? "
Fuel pump coming back on after the initial prime?
Take a look @ the Fp once it starts.

 

[DR BOOST]

i chased down a problem like this and it was the ignition switch. id get 12volts to the key on wires when cranking and wouldnt when i released the starter.

 

[tttype]

"Anything obvious that will shut it down right after it fires ? "
Fuel pump coming back on after the initial prime?
Take a look @ the Fp once it starts.

The elec fuel pres. gauge was rebooting during cranking, so thought FP may be an issue.
Setup a mechanical gauge onto windshield.
After it fires & dies the F.P. is still @ 42#

 

[tttype]

i chased down a problem like this and it was the ignition switch. id get 12volts to the key on wires when cranking and wouldnt when i released the starter.

After it dies I will check for power at the module.
Any easier or better places to check ?

 

[Chuck Leeper]

"Any easier or better places to check ? "
How about the exciter wire at the alt plug? It's hot w/ the key in on/run.

 

[tttype]

Have power to alternator exciter wire & cam sensor during cranking & on /run .

Turns out the engine will stay running as long as the starter is cranking.

Am thinking may have something to do with switching from cranking to afterstart fuel.
Its not flooding as will fire up right away after it dies.

Including a data file in case someone wants to have a look for anything really out of whack.

 

[HighPSI]

MAP Sensor?

 

[tttype]

MAP Sensor?

MAP reads 98 with key on, around 50 while running on starter.
Tried another sensor & has similar readings.

 

[tttype]

Swapped a friends coil/module in & car now runs.

Tested old one on caspers tester & it did nothing ?
How did it ever start then ?

First ever module on car at initial build tested fine, but didnt power crank & cam sensors.
That one took a long time to figure out !

Ethier Ive got bad luck or this car is hard on modules.

 

[Boost231]

atleast you figured it out