rough engine

[Sharroll Celby]

MAYBE a fuel "blockage" that is fine up to the 2000-3000 RPM range, is partially blocked at 2-3000, (hence the stumble), but higher RPM "blows past" the obstruction?

What conditions are your fuel lines?

Just a WAG.

[BAD ASP]

Originally Posted by Sharroll Celby

MAYBE a fuel "blockage" that is fine up to the 2000-3000 RPM range, is partially blocked at 2-3000, (hence the stumble), but higher RPM "blows past" the obstruction?

What conditions are your fuel lines?

Just a WAG.

I've got 60 lbs pressure to the FI logs, the plugs aren't showing lean on any cylinders. The fuel lines are stainless hard pipe to the regulator.
Hopefully I will be doing some work on the car tonight.
I'm in the construction industry and we're slammed with work right now..... so it's been hard to do any wrenching this week.
Thanks for the ideas guys. I'm noting all of these for this weekend.

[RICK LAKE]

BAD ASP Which box are you running? The old Speed pro, the Old F.A.S.T. box. There is a problem with them when running Large injectors bigger than72 lbs with low ohms. The drivers start to break down from the amperage loads, or duty cycles if you like. You could have the 4 injectors dropping out. Need the 6 digit number from the box for what you are running. 122131? You might need to go to a XFI box. I have had a couple of problem with the BOX. The new box has traction control built in. With the power you are maken, this might be a help. If you are on wide band O2, NO LEADED GAS. Is your are tuned with the Alpha N or the other way? The only fuel problem I could see is if the regulator is not upping the pressure when boost comes on. What is the ratio of boost to pressure on your regulator? 1/2 psi, 1/3, 1/5, 1/7? You should also have an LM-1 sensor on this motor to compare O2 readings. EGT is also not a bad extra. What ignition system are you running? You said the motor is popping in the exhaust. You need to fine out why, You could have the beginning of burnt exhaust valves, but this would happen all the time. I would look at the ignition first, new cap and rotor. Roadtest, then look at the timing charts. Rick L.

[BAD ASP]

Originally Posted by RICK LAKE

BAD ASP Which box are you running? The old Speed pro, the Old F.A.S.T. box. There is a problem with them when running Large injectors bigger than72 lbs with low ohms. The drivers start to break down from the amperage loads, or duty cycles if you like. You could have the 4 injectors dropping out. Need the 6 digit number from the box for what you are running. 122131? You might need to go to a XFI box. I have had a couple of problem with the BOX. The new box has traction control built in. With the power you are maken, this might be a help. If you are on wide band O2, NO LEADED GAS. Is your are tuned with the Alpha N or the other way? The only fuel problem I could see is if the regulator is not upping the pressure when boost comes on. What is the ratio of boost to pressure on your regulator? 1/2 psi, 1/3, 1/5, 1/7? You should also have an LM-1 sensor on this motor to compare O2 readings. EGT is also not a bad extra. What ignition system are you running? You said the motor is popping in the exhaust. You need to fine out why, You could have the beginning of burnt exhaust valves, but this would happen all the time. I would look at the ignition first, new cap and rotor. Roadtest, then look at the timing charts. Rick L.

Good stuff Rick, I'll be working on this over the weekend so I'll post soon.

Thanks to all for the help so far!