03 Cobra Hesitation and P0148 DTC

[Samtabulis]

I've recently purchased a 2003 Cobra with about 66,000 miles on it. It has just the basic mods; pulley, x-pipe, cat-back exhaust, CAI and Diablosport tuner. It runs great and is very responsive, until it hits about 5,000 rpm and then it falls on it's face. The first time it happened it felt almost like a rev-limiter kicked in. I pulled DTC P0148, so I changed the fuel filter with a Motorcraft filter (pulled out a Purolator...ugh) but nothing changed. From what I've read the FRPS is a pretty common problem, but it seems like people usually have more severe problems, like not starting at all or running horribly. Same with what I've read on the P0148 code. This car starts and runs great, just until it hits higher rpms. Any suggestions?

 

[KILRSVT]

i would check the frps still disconnect the hose and make sure no fuel is present..the code should describe some sort of fuel delivery error...i would also check fuel pressure and if you can check it while the car is under a load...

 

[Samtabulis]

I pulled the hose off the FRPS and there was no sight or smell of gas. I data-logged fuel pressure and ran it just through 1st and 2nd gear (I didn't push it too hard or wind it up very much). 1st gear I took it up to 5107 RPM and FRP was at 74psi. In 2nd gear I took it to just 4805 RPM and FRP was at 52psi. Should this be plenty of pressure? Do you think it's just in the tune?

 

[Chris01Bullitt]

Mine also did this in the 3rd/4th gears, put a kb bap in their and runs 100% again. Maybe not getting enough fuel through the longer gears...

 

[no2moro]

Restore the tune to stock. Could be a tune problem. If you still have trouble on stock tune then it is most likely your fuel pump. Very common problem.

 

[Fat-cat]

mine does this from time to time on dual GT pumps.. i havent logged it but i think im hitting a voltage cut on my FPDM

 

[Samtabulis]

What should fuel pressure be while under load at WOT with these cars? I data-logged another run today and it hovered around 46psi while under load. It peaked at 75 for a brief moment (I think the instant I let off to shift), but the majority of the time was 40-46.

I definitely want to get this dyno-tuned to ensure everything is proper (especially A/F), but don't want to get there only to be told I have a problem. I also don't want to throw parts at the car.

The fuel pressure I just read seems low to me, especially considering FP at idle is around 40. From what I've read, it seems like a KB boost-a-pump may help. What do you guys think?

 

[Wck'd01GT]

Did you replace the frps? I was racing the other night and sensed the major hesitation. Come to find out, my frps had taken a shit on me. Replaced it and runs like a champ now!

 

[lgonz051]

exact same thing happens to mine, i have same set-up as you except headers

 

[hemified86]

Hello, you guys figure out what the problem is. Sounds about the same problem I'm having. feels like I'm hitting mr rev limiter. I'm getting a kenne bell bap and a stage 2 fpdm. I will let know if that works.

 

[lgonz051]

im changing out my FRPS with a new one

 

[SonicTerminator]

i am having same problem intermittently except mine stops at about 4200. i have a BAP and modded fpdm. gonna try some fresh plugs and a new frps. any other ideas folks?

 

[lgonz051]

only way to tell is to tune it and run a diagnostic on the fuel system. and stay OUT of WOT

 

[silversnk30]

change the plugs. mine did the same thing i changed the plugs and it's back to normal.