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Fast XFI Hemi no crank signal

 
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lefty70



Joined: 12 Dec 2017
Posts: 4

PostPosted: Tue Dec 12, 2017 8:15 am    Post subject: Fast XFI Hemi no crank signal Reply with quote

Hello, hoping for some help. I have a complete Fast XFI 2.0 system with XIM. After some initial test starts, I have lost my crank signal. No crank or injector led's. I've tried a new crank sensor and testing wiring for continuity and resistance. My last resort was to send both units back to FAST for testing. After a week, I called and they said they both passed a bench and engine test. The engine is a new 2003-2008 5.7L crate motor. I am looking for a diagnostic tree for lack of a better term so I can figure out this elusive problem.
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stevieturbo



Joined: 29 Aug 2006
Posts: 1229
Location: Norn Iron

PostPosted: Tue Dec 12, 2017 4:35 pm    Post subject: Reply with quote

What exactly are you using for a crank trigger ?
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got blown

9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0
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lefty70



Joined: 12 Dec 2017
Posts: 4

PostPosted: Wed Dec 13, 2017 6:02 am    Post subject: Reply with quote

Everything is stock Mopar parts, besides the fuel delivery system and Fast. I've got no RPM so I've been told it's either the crank sensor, wiring or one of the modules. Wiring tested, sensor replaced and modules sent out for testing. Frustrating to say the least. I also reached through the sensor hole to verify the reluctor wheel wasn't broken. Seemed fine with no movement and engine is brand new so I didn't think that'd be the case but wanted to verify.
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old crow



Joined: 11 Feb 2006
Posts: 187
Location: Atlanta

PostPosted: Wed Dec 13, 2017 7:36 am    Post subject: sensor Reply with quote

maybe something you can use >

http://www.msextra.com/forums/viewtopic.php?f=131&t=59967
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Motorsports Mayhem 2008
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stevieturbo



Joined: 29 Aug 2006
Posts: 1229
Location: Norn Iron

PostPosted: Wed Dec 13, 2017 11:45 am    Post subject: Reply with quote

You need to be testing for a signal as installed, not sending parts elsewhere.

You may be able to get some sort of result from a basic multimeter, but ideally a scope of some sort. That will let you verify whether you have a working signal or not.
_________________
got blown

9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0
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lefty70



Joined: 12 Dec 2017
Posts: 4

PostPosted: Wed Dec 13, 2017 2:10 pm    Post subject: Reply with quote

stevieturbo wrote:
You need to be testing for a signal as installed, not sending parts elsewhere.

You may be able to get some sort of result from a basic multimeter, but ideally a scope of some sort. That will let you verify whether you have a working signal or not.

We tested system installed in the vehicle, notes from my technician:

tested for continuity and resistance on the three circuits from the crank sensor to the computer. Tested for 5v ref. and ground from computer. Tested crank sensor output at cranking speed: about 1.3-1.7v
Checked all circuits and fuses. Checked hall effect connector for proper terminal tension and possible backed out or damaged terminals.
No problems found.
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stevieturbo



Joined: 29 Aug 2006
Posts: 1229
Location: Norn Iron

PostPosted: Wed Dec 13, 2017 2:26 pm    Post subject: Reply with quote

That basic test shows something is happening.

Was this testing at the sensor, or ecu connector ?

Ideally you'd test with a scope to prove the actual signal is sound. A basic multimeter test cannot give you that, but that 1.3v reading is just an average of the switching voltage that may ( or may not ) be present during cranking.

If testing this at the ecu connector, that should prove wiring and signal to that point are sound.

Does the ecu itself offer no form of diagnostics for its triggers ?
_________________
got blown

9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0
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lefty70



Joined: 12 Dec 2017
Posts: 4

PostPosted: Wed Dec 13, 2017 2:41 pm    Post subject: Reply with quote

stevieturbo wrote:
That basic test shows something is happening.

Was this testing at the sensor, or ecu connector ?

Ideally you'd test with a scope to prove the actual signal is sound. A basic multimeter test cannot give you that, but that 1.3v reading is just an average of the switching voltage that may ( or may not ) be present during cranking.

If testing this at the ecu connector, that should prove wiring and signal to that point are sound.

Does the ecu itself offer no form of diagnostics for its triggers ?


It was tested at the sensor. I am not aware if the ECU has any diagnostic ability, do you have an idea how to access that? I have only used my laptop to install the GCT file to get it running, but I'm definitely new to this part of things. Thanks for your quick replies.
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