Possible Afr Issue

Discussion in 'Fox 5.0 Mustang Tech' started by tobalx, May 21, 2012.


  1. tobalx

    tobalx Member

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    i just installed my wideband and when i start the car i am lean at about 16-17.5 but when i give it a bump with the throttle it drops to about 14-15 at idle. if i don't burp the throttle it will idle lean. i have a custom chip burnt on the dyno. i had 19 lb injectors when the chip was burnt. i have changed to 30's with a pmas velocity maf. i have a 302 with gt40's 1.7 rr,e303,cobra intake and 70mm maf and shooting a 125 shot. my chip is a two position with a na and nos tunes. i just took it for a rip around the block and it looks okay to be about 10-12.5 at wot. im assuming the goal of 14.6 idle with 12.5 at wot is my goal.
  2. tobalx

    tobalx Member

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    here is a new chapter to this. i checked my fuel pressure and i am at 41 so i turned it to 43, with the vac line off i was ideling at 14.5 and gave it gas and it stayed around that mark. then when i put the vac line on it leans out to about 16 when i am giving it gas . know i am wondering if i even have the right injectors. i did the ebay thing and got bosch injectors that were recondition but look like 19's as they were orange. the guy swore up and down that they are thirties. now if they were 19's and i have a thirty pound maf i am sure i would be way leaner than that? what the hell do i do?


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  3. tobalx

    tobalx Member

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    please help, i'm supposed to race this weekend!!
  4. tobalx

    tobalx Member

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    well i found my problem the injectors are 30 lbbut at 60 psi, stay away from ebay i keep learning the hardway. the axxhole said they were the same as the red top frpp. they are rated 25 lb at 43 psi. i hope this helps someone. buy a afr guage. it definatly saved my motor, best 200 bucks ispent so far.
  5. DonMaximo

    DonMaximo Member

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    Fuel pressure should be at 39 with vacuum disconnected.

    Your chip was burned for 19lb injectors and whatever MAF you had before the PMAS.
    You weren't clear on whether the gt40's 1.7 rr,e303,cobra intake were on the car when the chip was burned.

    In any case, 30# injectors seems a little high for your changes, but most importantly, if your going to run laffin-gas, you'll want to tune the EEC (another dyno/chip burn or DIY) otherwise you're going down a dark path where things can get real ugly, real quick.
    In other words, would you have another car or ride to get to work ???

    As for fuel injectors, I would never buy someone's used parts, unless you're buying from a buddy and you know that he was good about maintaining fuel filters, never ran diesel through it accidentally (oh yeah, there's a story), water, sugar, etc.

    My 2 cents...

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