duncan01

Got my new gt40x heads installed with 24lb injectors/maf and set the timing on 14. The car is wanting to idle at 600-650 where before it was idling at about 900. I thought it was loading up due to the new injectors so I swapped them back for the 19lb's. Now im thinking that the idle setting was erased where the battery was unplugged for a few days. Also I noticed when I was setting the timing the closer I got to 10 degrees the worse it wanted to run and the closer I got to 20 the better it wanted to run. So I set it at a few different places and drove it, couldn't really tell much difference in performance but deff. wants to idle better with timing higher. All the timing adjustment where done with the spout out.

I guess my question is should I do a base idle reset to get the idle back to where it was and where should I set timing for my mods? Also, tps .94 volts. IAC is new, ACT is new, and ECT is new to eliminate those.

Mike T

Yeah, do a base idle reset. Set the timing at 13 or 14 degrees. How do you like those heads?

duncan01

So far pretty good. Ive noticed a pretty decent step up in torque which is what im after since its a street car. I will try the base idle reset and set the timing back to 14. Should I stick with the stock injectors or go back to the 24's? Ive always heard a little over 300 hp you should upgrade to 24's not sure where I fall but I told my mods to a guy at ford racing on the phone and he said I should be around 320 conservatively at the crank so...

Mike T

The 19# are good for 300hp and the 24# at 380. You've reached the limit for the 19's, put the 24's back in.

duncan01

Thats what I was afraid of. Reckon ill tear the intake back off and swap em out.

duncan01

update: put the 24lb injectors back in and did a base idle reset, shes idling about 750 with a nice lope (may increase). With the new heads and injectors she really comes alive around 3K rpm. Seat of the pants feel is pretty significant over the stock set up I was running. Changed the tone of the car too has a much harder hit, which is expected with increase in compression.

Duncan_GT

My 5.0 idles at about 700, sounds like you're in the ballpark. 900 seems a bit high to me

dawson1112

Mine is at about 750 rpm idle so your right in there . You can tweak them a little on the sn95s with the idle air valvle that is located on the top of the throttle body , but your in a good range for that motor. As a lot of us have discovered with these efi cars any time you change air flow coming into the engine you need to redo the idle learn procedure. Good job on the diagnosis.

duncan01

Thanks,
I only have a few trips around town on it since this was all completed. At first almost everytime I pushed the clutch in it would stumble and die. Thats why I thought I needed to up the idle, and its loping pretty good. The more I drive it the less it seems to stumble. I guess its still relearing but if it continues to fall on its face with more driving ill prbably up it to about 800 or so. When coming to a stop light and I would push the clutch in and the rpms would fall then at the last second it seems like the computer would tell it, "Hey your supposed to recover here" and not quite make it.

lurch69

You can go with 24 lb injectors with 255 fuel pump but need a regulator.