Boost Problem

[INTRIGUED]

Well everytime I build boost I get this stutter problem and there is zero pull. Its all around the powerband and its kinda pissing me off. I have a walbro 255hp with a rewire in it right now. ported 14b stock FPR and 2g o2 housing 2g exhaust mani S-AFC-I (for what its worth) Hughes thinks its the FPR getting overrun but I'd just like any other suggestions on what you guys think it is. Maybe just a boost leak? or maybe both?

Any input would be great!


Sidenote: Hughes I'm not second guessing what you said just seeing other views! :)

[Wizard]

Check plugs, plug gap (0.028) and wires. Start there......I never had a problem with FPR overrun and doubt you really have that problem too. Neither did Al Blaha. Who ran 10.5 at 132 with 2g pistons, stock rods, 1g BOV, 1g FPR, 1g MAF and AFC-1.

Wiz

[Kracka]

A rewired 255HP supplies way too much fuel for a stock 1G FPR to handle. Oh, and for Cory's setup, a .030" gap on the spark plugs is favorable to a .028" gap considering he is running stock boost on a stock turbo.

[INTRIGUED]

Thanks for info


Anyone have a walbro 190 around and would like a 255hp? ;)

[Shane@DBPerformance]

FPR overrun is just a big excuse. If people can't tune out some extra fuel pressure, then they are going to have some problems when they goto big fuel injectors.

[JET]

If you are overrunning the stock FPR, you are going to overrun it the most at idle. Is your idle all messed up? If not, then it more than likely isn't the FPR. Try unhooking the rewire and just run the stock wire to see if it helps.

It sounds like a spark problem to me. I run a max of .028" for a spark plug gap too. .026" on higher boosted cars, but I don't think that is your problem. Have you tried swapping wires with someone?

[1ViciousGSX]

Any other mods on the car?

[Kracka]

I'm doubting this is a spark issue, the stuttering generally clears up around 6000-6500 rpm's and pulls strong all the way to rev-limiter...sorry Cory ;) I tuned out most of the stuttering, but the weather got a lot warmer over the past few days in Duluth (I'm in the Cities for the week) and now Cory says its doing it across the entire powerband. Oh well, next week we'll play with it more and see what we can come up with; along with getting some new plugs since they should be in-stock by then at Archer.

On a side note, did it stutter while in the Cities, Cory? My DSM's always ran like ass in Duluth but perfectly in the Cities. That town is so gay :D

[Kracka]

His mods include whats listed in his first post plus a K&N and full exhaust. Speaking of exhaust, we'll have to hook up your boost gauge (when it arrives with the mbc) and see if the exhaust is causing you any boost creep.

[JET]

Craig's exhaust was causing him to creep to 21psi! That could definately be a problem too. It was detonating like crazy!