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Old 09-21-2009, 05:22 PM   #1
Will86
 
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Default will not hold idle, runs too lean

Hey guys,

I have a 93 Mustang Cobra and just finished installing a bunch of mods including AFR Street 165cc heads, trick flow upper and lower intake manifolds, crane cam (part # TFS-51402000) 24lb venom injectors, and a BBK fuel rail with an Accufab adjustable regulator.

I was able to get the timing dialed in and break in the cam however I cannot get the engine to hold an idle. If I slowly back off the throttle the engine will idle rough around 900 then eventually die. If I rev the motor up and let the revs fall naturally the motor will instantly die. I pulled the some of the plugs and the motor looks like its running extremely lean.

I used to have a C&L 76mm mass air flow housing, however, it ran better when I swapped the stock housing back on the engine.

I originally thought my issue was vacuum related. I checked all lines and gasket surfaces over and was unable to find and sources of vacuum leak. I also had a master mechanic look at the car and he ruled out a vacuum leak. Even if the injectors were to small for this setup I doubt their duty cycle could be maxed out at idle. Has anyone else run into this issue or have any suggestions on how to remedy this problem? Thanks!
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Old 09-21-2009, 06:39 PM   #2
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fuel pressure?
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Old 09-21-2009, 08:01 PM   #3
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base idle relearn proceedure
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Old 09-21-2009, 08:23 PM   #4
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^^agree, turn up the base idle. You have the IAC hooked up? Ever try and pull the codes?
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Old 09-21-2009, 08:45 PM   #5
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Fuel pressure is nearly maxed. The IAC is plugged in. To adjust base idle I just turn the screw on the TB right?
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Old 09-21-2009, 09:14 PM   #6
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Quote:
Originally Posted by Will86 View Post
Fuel pressure is nearly maxed. The IAC is plugged in. To adjust base idle I just turn the screw on the TB right?
why is your fuel pressure maxed? it should be at 39psi
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Old 09-21-2009, 10:28 PM   #7
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I will be watching this one as my 1990 is acting very similar. Only when hot and not all the time.
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Old 09-22-2009, 08:04 AM   #8
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Quote:
Originally Posted by AdderMk2 View Post
why is your fuel pressure maxed? it should be at 39psi
I have the screw on the regulator almost all the way in. I still need to put a gauge on it though so im not sure of the exact pressure.
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Old 09-22-2009, 12:38 PM   #9
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Quote:
Originally Posted by bosspsd View Post
I will be watching this one as my 1990 is acting very similar. Only when hot and not all the time.
If it surges could be the EGR,or TPS too
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Old 09-22-2009, 01:31 PM   #10
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Quote:
Originally Posted by Will86 View Post
I have the screw on the regulator almost all the way in. I still need to put a gauge on it though so im not sure of the exact pressure.

get a gauge on there before you do anything else. 39 psi with the vacuum disconnected and capped.
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