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FiTech Issues

JORDINSKI

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11:37 PM
Joined
May 25, 2021
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Location
Tucson, AZ
I have a 67 GTX with 30003 Go Street EFI System. I hear a large hissing sound while idling. When I put car into gear I make it about 100ft before I loose complete engine power and vehicle stalls. I do have throttle response while idling. I wish my first post could have been a pleasant one. Any help would be greatly appreciated.
 
Go to Fitechtuning.com or search fitech on FB or call them.
 
What size engine? I have tuned a few fi- tech systems but my vast majority of my
Experience is with the FAST system on my dads 68charger. I had similar issues with dads 440. Long story short I ended up opening up the throttle blades with the idle screw and re-Cal the tps. Sometimes takes a few seconds to slow down to the 800 rpm idle I have it set at but no longer stalls. The hissing you hear is the fact the likely your idle air motor is open quite far and there is lots of air bypassing in the throttle body. By allowing more of this air to go directly past the Throttle blades you will hear less hissing and hopefully will eliminate your stalling issue. On the fi tech systems I’ve tuned they have been on small blocks and the idle air issues are less due to less air requirements at idle with a smaller displacement.

good luck and hope you get your issues fixed.
 
What size engine? I have tuned a few fi- tech systems but my vast majority of my
Experience is with the FAST system on my dads 68charger. I had similar issues with dads 440. Long story short I ended up opening up the throttle blades with the idle screw and re-Cal the tps. Sometimes takes a few seconds to slow down to the 800 rpm idle I have it set at but no longer stalls. The hissing you hear is the fact the likely your idle air motor is open quite far and there is lots of air bypassing in the throttle body. By allowing more of this air to go directly past the Throttle blades you will hear less hissing and hopefully will eliminate your stalling issue. On the fi tech systems I’ve tuned they have been on small blocks and the idle air issues are less due to less air requirements at idle with a smaller displacement.

good luck and hope you get your issues fixed.

It is a 440. I forgot to mention that it had a backfire through throttle body the other night that could be related.
 
Hopefully that didn’t damage anything....
If your backfiring through the intake do you have timing issues? Check and verify your timing. what kind of engine build? Stock or modified?
 
I would start tuning without PCV hooked up, Distrubitor vacuum advance connected to manifold vacuum (not ported), and a fuel pressure gauge on the inlet fuel line to make sure there is no issue with fuel pressure.
Let the engine come up to operating temperature, and set the desired idle RPM, at first maybe even a slightly higher idle rpm.
Then set idle O2 a bit rich, maybe 13.5:1. Then manually adjust the throttle blades so the IAC count is about 2-8. Save settings.
I think the FiTech/engine needs to be turned off and re-started between adjustments/setting changes to re-calibrate the TPS position and maybe update other software changes?
The self-learning is only for air/fuel after the engine is warned up and over (I think) 170 degrees.
I had issues with the Decel fuel cutoff, cutting too much fuel on deceleration.
 
Agreed with above. More details would help, but hissing sound at idle/stalling/backfiring is an indication the iac valve is running at the end of it's open range and not enough initial timing.
 
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