400hp 351w startup tune

[Sevensecondsuv]

The regulator for the same year truck with a 4.9L straight six will have a ~55 psi regulator. Ford upped the fuel pressure on the straight sixes to combat vapor lock in the fuel rail due to it sitting directly above the exhaust manifolds.

[efloth]

Yeah, I found an old one from my 4.9 but it would have to be modified to mount up correctly. I'll just run the stock regulator for now.

[efloth]

Failed emissions at idle today. Allowed is 100PPM of HC and she read 239PPM. It is a bit rumpety at idle, so it has to be the cam profile causing it. At 2500RPM, 180PPM allowed and it read 15.

Idle speed is under 700rpm so thinking I need to kick it up a bit to pass. Timing jumps around 15-25 degrees at idle. Any other help? Some have mentioned leaning it out a bit but not sure how to force OL at idle.

[red5.0fogger]

2500 rpm 15ppm is good, so the cats may not be hot enough at idle. Also locking the timing at 10 is helpful. I would try a higher idle speed like you said (850-900ish) but they may have a max idle speed requirement...

[efloth]

Awesome, I set the idle to 850 and timing at 13*. at 10 it hunts a bit more I think because the minimum idle timing is 10. Should I lower the minimum or leave at 13?

I'll be having it tested again in the morning. I noted that the engine needs a bit more air and fuel at idle now. Is the flame burning into the exhaust port increasing temps?

[red5.0fogger]

Yes, the later burn sends more heat out the exhaust which gets the cats up to temp. 13 will prob still work.