Boost Problem

INTRIGUED · 03-22-2005

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 · 03-22-2005

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** · 03-22-2005

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 · 03-22-2005

Thanks for info

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

**Shane@DBPerformance** · 03-22-2005

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** · 03-22-2005

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** · 03-22-2005

Any other mods on the car?

**Kracka** · 03-22-2005

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

**Kracka** · 03-22-2005

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** · 03-22-2005

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

INTRIGUED · 03-23-2005

I'm going over to archer's today, I talked to jermey when I was out last night and he said he would take it for a spin and add the 6th or 7th opinion on what he thinks it is

I picked up some new plugs just the other day. Havent had time to throw them in yet.

The car drove perfect in the cities when I got it! Damn this town!

**1ViciousGSX** · 03-23-2005

By chance, have you checked or made any adjustments to the fuel mixture? Sounds like it could be running lean.

**JET** · 03-23-2005

Has the timing been messed with lately? It will detonate easier in the midrange due to timing than on the top end.

INTRIGUED · 03-23-2005

I'm going to mess with it some more today. I will throw the new plugs in too. I also thought of one other thing. Maybe the FPR is broken? *shrugs* I'll update you guys later today.

Cory

A//// Guy · 03-23-2005

My car used to do the same thing. I think you have a spark problem. How are your wires? I bought new Taylor SP wires and the stuttering went away. It was mainly under full boost and around 3k to 5k. This was about 2 years ago...

INTRIGUED · 03-29-2005

Well, Hughes and I installed my boost controller and boost gauge, and new plugs among other things and set the boost and she drives like a champ!

**Kracka** · 03-29-2005

I actually need to do some more tuning tonight on it, a few things are raising a concern with me.

A//// Guy · 03-29-2005

Tune it eh Hughes? You know you just like driving a 1G again

So was it just spark?

**Kracka** · 03-29-2005

Retuned the low-throttle settings and made a few other adjustments and everything is looking good and the car is pulling like a beast with little to no knock. As far as I can tell, the problem was resolved with the incresed boost level. The plugs in there were perfect condition BPR6ES's gapped properly. We put 7ES's gapped at .030" in and left the NGK wires the car came with on.

Yes, I am loving the quick 1G around, its tons of fun that I forgot how much I loved

INTRIGUED · 03-30-2005

Now hopefully I can get that damn fuse problem fixed! Got pulled over 3 times last night!