New (to me) '04 Cobra - Some Hesitation when in boost?

[hand-to-ball]

Hey everyone,

Just got myself an '04 Cobra and it accelerates and idles fine. However, when I peg it and go into full boost (say around 3k rpms), the car either sputters a little bit (kind of like a slight shuddering) or it'll surge a little bit, making for a non-smooth pull to 5 or 5.5k rpms. The power is pretty much there and the boost guage hits '8' psi, but its not a clean pull.

Going to the dyno this week to check out a/f and things like that, but does this sound familiar to anyone? Hoping its just a/f, plugs or belt slip and nothing more...thanks and I look forward to contributing!

Oh sorry - stock pulley, intake and exhaust, 40k miles...

 

[Tom's_03SVT]

plugs, COPS or MAF.

 

[PA SNAKE]

PPRV.... possibly...?

 

[hand-to-ball]

plugs, COPS or MAF.

Sorry not familiar with COPS? Coil packs? Also not sure what PPRV stands for either...thanks guys!!

I'm definitely checking the plugs and mass air at the dyno this week...

 

[04sleeper]

First thing is to check the basics. Plugs, Coils, etc....

Then I would try to datalog it while its doing it and see if you come up with anything.

 

[About2bite]

Replace your plugs, spark plug blow out more than likely.

 

[Qwk GT]

sorry, but what does pprv stand for?

 

[Screamin Cobra]

sorry, but what does pprv stand for?

Positive Pressure Relief Valve

Its the culprit that causes a hesitation between shifts during WOT. Most can avoid it by powershifting.

 

[hand-to-ball]

Replace your plugs, spark plug blow out more than likely.

Yep, going to do that tonight. Been reading about plug change frequency and seems I am waaaay overdue...I think mine are the originals with 48k on them!! Also, the car sat for the last two years having only been driven infrequently over that time and have been told that long lay-offs aren't that good for this car.

I bought some Autolite 103's since the NGK TR6's are impossible to find locally. I mostly read decent reviews on here for the regular Autolite 103's (copper core) and they're only $1.75 each!

Hopefully that cures it, either way I never knew plugs were SO important to the driveability of this car.

 

[hand-to-ball]

Yep, going to do that tonight. Been reading about plug change frequency and seems I am waaaay overdue...I think mine are the originals with 48k on them!! Also, the car sat for the last two years having only been driven infrequently over that time and have been told that long lay-offs aren't that good for this car.

I bought some Autolite 103's since the NGK TR6's are impossible to find locally. I mostly read decent reviews on here for the regular Autolite 103's (copper core) and they're only $1.75 each!

Hopefully that cures it, either way I never knew plugs were SO important to the driveability of this car.

Quoting myself here, but my tuner had NGK TR6's and he swapped them out tonight and gapped to .032 - what a difference!! The hesitation is gone and the pulls in boost are A LOT smoother. BTW, original Motorcrafts were in there at .050

Oh, baseline #'s - 357 hp / 366 tq - I'm pretty happy. Cat back and intake are next...

 

[vicmaster]

Nice to see another MA Cobra. Where are you located? Where did you go to get it tuned?

 

[04sleeper]

BTW, original Motorcrafts were in there at .050

 

[Hawkdriver23]

My cobra started doing this...had to step up and swallow the $9 TR6ix's. It a slight stumble at idle, but then a good strong lurch under hard acceleration when it misses. Not Cool, new plugs Going in tuesday.