Top end studder

[J Speak]

Top end studder under boost. Iac is 43 and it will not go lower. Blm 136 at idle warmed up, no vaccum leaks found. 15lbs vaccum at idle. Running TT chip and 45 lbs fuel pressire line off. It was fine until I laid into with a 1/4 tank of gas. It studdered like lack of fuel so I let off. I filled it up and it studders on top end under boost once out of every 3 times. Currently running open dump with 26lbs of boost. Has run 30lbs previouly but I turned it down.


Thanks for the help.

 

[turbo nasty]

Batt Volt at WOT? How old are plugs? Fuel psi at WOT? MAF counts at WOT?

 

[J Speak]

How can I get this info? I have a scanmaster only

 

[turbo nasty]

Plugs you should know brotha! Scanmaster shows batt volts and maf counts. Fuel psi will require a gauge. Also, check your vacuum lines to your fuel psi reg

 

[michael evans]

How can I get this info? I have a scanmaster only

Maybe you need to look into data logging. I know it has helped me figure out some stuff.

 

[Chuck Leeper]

^^^ This.
Also, next time you do a WOT, check the oil pan for holes.

 

[Mr.Spool]

Top end studder under boost. Iac is 43 and it will not go lower. Blm 136 at idle warmed up, no vaccum leaks found. 15lbs vaccum at idle. Running TT chip and 45 lbs fuel pressire line off. It was fine until I laid into with a 1/4 tank of gas. It studdered like lack of fuel so I let off. I filled it up and it studders on top end under boost once out of every 3 times. Currently running open dump with 26lbs of boost. Has run 30lbs previouly but I turned it down.


Thanks for the help.

in addition to what others have suggested,compression test the motor and check all the hoses from throttle body,intercooler and turbo.verify fp rising 1 to 1,and check meth pump for leaks

 

[J Speak]

Pulled plugs. Number 4 loose and number 6 fouled. Replaced from 44 to 43 with the addition of .32 gap and it runs like a dream again. 777 on scanmaster with zero knock at 27 lbs of boost. Iac still at 45 and blm at 135 in drive at idle 875 rpm. Im going to watch number 6 plug. Everything else checks out as far as hoses and leaks. I wonder if i have a small crack in the headers or crossover. Ive welded the driver side header and crossover flange. No leaks when I put it together.

Im looking at power loggers now. Ive been out of buicks for over 8 years. This was my first one I bought in 04 and sold in 2010. I was lucky enough to get it back from my buddy

Thx for the info

 

[phil_jordan]

That's awesome that you found your problem!

 

[J Speak]

in addition to what others have suggested,compression test the motor and check all the hoses from throttle body,intercooler and turbo.verify fp rising 1 to 1,and check meth pump for leaks

I am going to replace all vac hoses this winter. My FP gauge is under the hood. Maybe a dyno run will help out. Will a powerlogger pickup Fuel pressure?

 

[RUQWKNF]

I am going to replace all vac hoses this winter. My FP gauge is under the hood. Maybe a dyno run will help out. Will a powerlogger pickup Fuel pressure?

If you purchase a 5v 100psi pressure transducer, and plumb it in place, or in conjunction with your underhood fp gauge, the Powerlogger can datalog fp. However, without plumbing in a transducer, it won't datalog fp.

 

[J Speak]

Thx

 

[Mr.Spool]

My FP gauge is under the hood.

i cant say this enough.need to see it in real time!,under the hood is useless,and logging is after the fact and is great at finding the smoking gun.

 

[michael evans]

I am going to replace all vac hoses this winter. My FP gauge is under the hood. Maybe a dyno run will help out. Will a powerlogger pickup Fuel pressure?

Have a transducer I just took off when I went from the factory computer to the FAST system.

You can see the fuel pressure in real time with it.

I would run all thee wires from the block if I were to do it again as there are short cuts.