Minnesota Focus Owners Club

Hello, MN Focus people. I have an '04 SVTF with a Jackson Racing Supercharger + the Big Boost Kit (JRSC+BBK). The kit came with new calibration courtesy of Ford Racing. My car runs great, and has more power than I know what to do with (HINT: You cannot floor it in 1st gear - even from a roll - without lighting-up the tires!).
Anyway, it runs great except for a "stumble" at about 2,500 RPM. It is most noticeable at light to moderate acceleration. It is hardly noticeable in the lower gears, but is most significant in 6th gear. It almost feels as if someone momentarily shuts off the ignition or the fuel supply.
Okay, I checked with Ford Racing, and they stated that this is basically “the nature of the beast”. In other words, this “stumble” or “stutter” is inherent in the calibration (program) of the ECU. I asked them, “Is it correctable?”. Their response, “No.”
I also asked if this would cause engine damage, since I routinely have my cruise control set at 2,500 RPM (2,500 RPM = about 60 MPH). They stated that it will not harm the engine. I sure hope this isn't a bunch of baloney!
Anyway, is there anyone in the Twin Cities (or thereabouts) who can dyno & tune this thing? I'm looking for someone who is knowledgeable with SVTF's. I checked with RS Motors in Burnsville, but he doesn't have any Focus experience, and doesn't have the software, etc.
Thanks in advance.

Hmm i dunno anyone but be careful of that stumble that cannot be good if its losing fuel... ive been hearing alot of horror stories with boosted svt's makes me wonder if i will ever boost mine

I know Pappy is planning on having db performance tune his car (zetec jrsc) next year. They are pretty good tuner from what i heard and I believe they tune Xcal2 only. I've also heard Hitech in ramsey, mn is pretty good with focus. other then those 2, mcnews and focus sport are the only 2 I heard mentioned alot outside MN. I used to have a zetec jrsc bbk, mail order tune and it didnt stumble like yours so it makes me think it has something to do with the tuning. Do you have wide band by chance?

Talk to Danny at DB performance. DO NOT goto RS Motors... Ron has no idea what he's doing, I can think of a few peoples cars he blew attempting to tune them.........

My car has the same 'stumble' as yours. I know exactly how you feel, it's rediculously annoying. Dan said it can be tuned out with SCT and some dyno and street tuning. It isn't hurting anything though internally, it's just an annouance driveability issue.

They are extremely competant in what they do. Dan is the guy, pretty much all the HIGH horse power fords (ex. 1400whp TT Mustangs) go to for tuning. I've had him fiddle with my car quite a bit already and have had it on his dyno multiple times. He knows his stuff. I can't wait to have him build me a custom tune from the ground up, when I pull my car back out for next year.

763.428.9882 - Ask for Dan. Tell him Nils with the Blue JRSC'd focus sent ya. He'll hook ya up, he likes us mnfocus guys

Regarding wideband - no, I don't have one.
Thanks for the reference about Danny at DB Performance. I'll give him a call.

Hey, Good to see you here Jim. Looks like the guys have pointed you in the right direction for tuning.

Question, What throttle body does the JRSC use? I almost wonder if it's a throttle body design issue.

Steve,
Greetings to you too!
The throttle body is the original SVT unit (no mods). The BBK kit supplied a different MAF and new (larger) injectors (along with a new fuel rail).
My biggest concern is that this stumble will somehow damage the engine. Ford Racing said that it would not damage the engine, but I fear that they might be just blowing me off. I'll email you privately with the Ford Racing contact so you can inquire, if you like.
Since the conversion, my chrome exhaust tip has a black haze (easy to wipe off). It had this even before the weather turned cold. I'm speculating that this is from a rich mixture. My car does not burn any oil.
Your thoughts, please.

i think you can use any TB on the JRSC. i know the car i got had the FC 65mm on it, but nils put the ported stock one back on.

Your exhaust tip is black, because the car is to rich... I have the same problem. I'm running 10.5:1 A/F.... PIG RICH! It should be closer to 12.5:1.

The stumble isn't going to hurt anything. What it is, is a fuel pooling issue. From all the added fuel, yet not using any power down low to burn it up. This has to be personally tuned out (as the mail order tunes come INSANELY rich, for safety reasons... but, this leads to driveability issues and loss of potential power). This stumble can be tuned out, but no, it isn't going to hurt anything.

oldoutboardjim wrote:Steve,
Greetings to you too!
The throttle body is the original SVT unit (no mods). The BBK kit supplied a different MAF and new (larger) injectors (along with a new fuel rail).
My biggest concern is that this stumble will somehow damage the engine. Ford Racing said that it would not damage the engine, but I fear that they might be just blowing me off. I'll email you privately with the Ford Racing contact so you can inquire, if you like.
Since the conversion, my chrome exhaust tip has a black haze (easy to wipe off). It had this even before the weather turned cold. I'm speculating that this is from a rich mixture. My car does not burn any oil.
Your thoughts, please.

I think getting it to DB is the answer, It does sound like you're running rich.

The guy that's been tuning mine has been doing it via e-mail, I get the car to a dyno and get the runfiles from a couple pulls and then e-mail him the runfiles.

He looks at the air/fuel and tweaks the tune a little bit, it's a slow process but it works. I just got a new tune file today that I should be loading tonight.

i agree with the pappy. the mail tune is set rich to cover some ones ass, very hard to burn pistons with all that extra fuel. DB perf should be able to tune it out. you would think that going to a step smaller injector would limit the amount of fuel. although it would cycle them longer and potintialy damage the injector.....hmmm weird.