Mustang issue

[Amiller6]

I have a 95 mustang gt I put gt40 heads gt40 intake and a b303 cam it’s surging between 800 and 1100 rpm’s the rpm’s hang when I let off the peddle it’s jerks while driving I set the timing at 10 degrees and it’s very sluggish when you take off almost sputtering I don’t know what to do it’s my first build I did use the fuel rail off the donor motor idk if that would cause an issue with the regulator being different there are no vaccum leaks I deleted the egr. Do I have to have a tune? Idk

 

[86HO5.0]

If the stock ECU is still being used a tune will be necessary with that cam.

You could also put the stock HO cam back in and throw some 1.7RR's on.

 

[AeroCoupe]

Stock ECU does not need a tune with those mild mods. You need to go through the surging idle check list. Also, have you tried pulling codes? The CEL only comes on with emissions related codes so there could be other codes with no CEL.

Help me create the "Surging Idle Checklist"

Updated 05 July 2022 to add rough idle when cold and smooth idle when up to normal operating temperature. See the EGR tech information, section #15 for more help. Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank...

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