Hello everyone... First post here but I've been lurking for a few years now learning what i can. I bought my 05' VIII about 2 months ago. Anyways on to my question..

I just got home from having a Greddy Profec II boost controller and nice matching Greddy turbo time installed. First impressions from giving the car a nice run through the gears with the percentage set at 51%. For those of you not familiar the shop i got the work done told me it should equate to right around 19.7 or 19.8 psi. (www.amstuning.com which did a great job by the way) Anyways once the car got up to around 5k rpms it felt very notchy. The pull kind of felt staggered.. basically not very smooth. I mean dont get me wrong.. this isnt an extremely noticable thing but since im used to driving the car everyday, i can feel it.

I was told by the shop that the next modification should be an upgraded fuel pump.

So my question is could the notchy feeling im experiencing be caused by my stock fuel pump not providing the proper ammount of gas i need now? Do you think that would smooth things out? Getting a Walboro pump is a pretty inexpensive mod so im just curious how important it is to get done at this point and if it would smooth things out? Thanks

BTW my only mods are the boost controller/turbo timer/drop in K&N.

 

do you have a boost gauge to verify the preset boost level set by the shop?

 

sounds more like spark plug blowout to me

if you run out of fuel, the car will buck hard

get a boost gauge to verify your actualy boost pressure , i guarantee your overboosting at the moment

 

Well the car has 1900 miles on it so i doubt it would be a spark plug failure right?
Or did you just mean that one of the spark plugs could have come out of place a bit?

I dont have a boost gauge but the profec II i have reads out your boost level on the screen in real time as you go.... it never went past 19 when i did a 4th gear pull. I had my friend in the car to verify and watch it as i went.

I asked another friend of mine and he said it could be knock and that i might need some tuning/upgraded fuel pump or maybe just the fuel pump by itself.

 

Rustang Cobra means that the plugs are not maintaining spark when boosting that high. Most turbo cars need to gap the plugs down or get colder plugs in order to stop this. Fuel cut is very violent and would feel different than high end miss. The miles you have on your car doesnt matter at all.

 

Mekka, if you search some more on here there is a big thread about that boost controller and its settings. I have had mine for about 3 months now and it can be very finnicky. I would have a lot of boost stutter if my gain was past 14-15%.

 

exactly, it has nothing to do with the spark plug failing over time

spark plug blowout occurs when the gap between the plug and electrode tip gets blown out before causing combustion in the cylinder, so the car feels like it skips a beat and doesnt accelerate

put in some NGK copper plugs and gap them down to .036 or less and you should be good to go