Mach 1 2003 mach 1 with 5.4 dohc heads

[03mach1P1SC]

Ok i have a 2003 mach 1 that im daily driving and i did a navigator head swap and did some stage one porting and a valve job and sct custom tune and what not well ever since i did that swap my car has mis fire and have tried everything i bought all new 24lbs ford racing injectors BWT coils replaced all coil connectors and new spark plugs and im replacing O2 sensors tomarrow and if that doesnt fix it i would like to know if maybe im not getting enough fuel and need bigger injectors idk some one help me out PLEASE im stumped




and btw just im about to put my P1sc stage 2 9psi air to air intercooled kit back on as soon and i can afford to have the car down again but what size injectors and mass air flow sensor should i get? any help is appreciated

 

[bradfier]

I haven't heard of many people putting on the 5.4 heads, what is the difference?

 

[03mach1P1SC]

after i put the 34lbs injectors and retune it ill keep you posted but i know the navi heads flow pretty close to the gt 500 heads and there aluminum so once i get that done ill be posting real soon but with 24lbs injectors and tune it ran lean under normal driving conditions but under full throttle i made 349rwhp and 36xtq

 

[Superstang03]

Old thread but doing extensive amounts of homework on heads, IMHO your stock mach1 heads kicks these heads asses unported.. port them mach 1 heads and EVEN ported fr500 heads don't touch your stock heads ported..

Here is Part of one article.....

'03 DOHC Heads ('03 Aviator, Marauder, Cobra, Mach 1, Australian Boss 260/290): Featuring the same ultra-high-flowing intake port as FR500 heads, but combining it with a newly designed larger and more rectangular exhaust port, these may be the best all-around DOHC Ford heads yet. For those with a forced-induction street motor, they are without question the best heads available. As with the FR500s, they should produce great power even beyond 8,000 rpm, regardless of application.

Andy had this to say about his final choice of cylinder head. "The decision to use Navigator heads for the 5.3 featured in this story was a fairly simple one. The combination of a tumble-port intake design and slightly more intake port volume than a regular C head seemed like a winning combination for an 8,000-rpm naturally aspirated motor of larger-than-normal dimensions. If I could do it over, I would use '03 DOHC heads without question. The reason is that there is a much broader selection of intakes to use with the '03 DOHC heads than with Navigator (5.4) heads on a 4.6 block. The larger 5.4 heads don't leave a lot of room in the valley for the lower portion of an intake to sit, essentially requiring the use of either an ultrashort runner (highly modified) '99-'01 Cobra intake or a custom sheetmetal unit."

Read more: Four-Valve Cylinder Heads - 5.0 Mustang & Super Fords