Stuttering Topend Please Help

[NeOzz1]

Car runs fine until it get to about 5900-6000 rpms then it starts to stutter.

mods
evo3 16g
full 3 inch
sbr manifold
10psi!
walbro 255
fpr

other minor stuff

1st gear till redline no problem
2nd gear till about 600-6500 stuttering starts
3rd 6000-6300 stuttering starts
4th 5900-6000 stuttering starts
5th have not revved it that high

any ideas would be greatly appreciated

I just bought the car so I can only answer so many questions but go ahead and ask if it will help me fix it

 

[oldman]

1. Which afpr and what psi is it set at?

2. How old, what type and gap size of the spark plugs?

3. Have you done a intake leak test?

 

[NeOzz1]

1. Which afpr and what psi is it set at?

2. How old, what type and gap size of the spark plugs?

3. Have you done a intake leak test?

1. B&M 43psi

2. Brand New NGK brp7es and NGK Wires, did not gap them(did not realize i needed to and they worked fine without gapping in my other car)

3. No Intake leak test, that will be tomorrow probably

 

[oldman]

1. B&M

Command flo?

43psi

With or without vaccum line?

2. Brand New NGK brp7es and NGK Wires, did not gap them(did not realize i needed to and they worked fine without gapping in my other car)

Re-gap them to .028", you may need to go back to 6s as 7s might be too much for 10psi but try other things first.

3. No Intake leak test, that will be tomorrow probably

http://www.vfaq.com/mods/ICtester.html

 

[NeOzz1]

Command flo?


With or without vaccum line?


Re-gap them to .028", you may need to go back to 6s as 7s might be too much for 10psi but try other things first.


http://www.vfaq.com/mods/ICtester.html

Umm
command flo? <IDK
its a small silver one on the end of the rail

dont know what vaccum line u r referring to

you think the gap would even make a difference?

 

[NeOzz1]

BTW i will be running more then 10psi its just the car has not run well enough that i was confident enough to turn the mbc up

 

[oldman]

Umm
command flo? <IDK
its a small silver one on the end of the rail

afpr. Can you turn the pressure down?

dont know what vaccum line u r referring to

Do you see a vacuum hose connected to the afpr?

you think the gap would even make a difference?

Big time, especially at higher rpm.

BTW i will be running more then 10psi its just the car has not run well enough that i was confident enough to turn the mbc up

Wait until you figure this out and that a leak test is performed.

 

[NeOzz1]

Cant here noise but cant find the leek, almost likes its inside the engine, it loudest on the left side facing the engine bay but i cant find anywhere its coming out, still have not gapped plugs will do that next

 

[oldman]

While you check for boost leaks and re-gap plugs, I just want to remind you to answer my afpr related questions. Whether there is a vacuum hose connected to the afpr, 43psi is way high. 1G base setting = 37psi without vacuum line, with vacuum line it should read 28psi. You're overrunning the fpr by 15psi.

 

[NeOzz1]

I cant check the psi just by letting it idle right? going to do it right know

 

[oldman]

I cant check the psi just by letting it idle right? going to do it right know

That is exactly how you set base pressure, at idle.

 

[NeOzz1]

gapped plugs, didn't help
had small boost leak but its fixed now, didn'thelp

FPis at 42 idling with a vaccum hose going from the fpr to the little soleniod by the top of the windshield

 

[oldman]

gapped plugs, didn't help

http://www.dsmtuners.com/forums/showthread.php?p=1679803#post1679803 Check the conditions of your wires as well.

had small boost leak but its fixed now, didn'thelp

Oh yea, how much pressure did the system hold and for how long?

FPis at 42 idling with a vaccum hose going from the fpr to the little soleniod by the top of the windshield

You're definitely overrunning the fpr. Pull the vacuum line off and try adjusting it down to 37psi. If it won't let you, you have the B&M Command flo which is the wrong fpr for our cars. With that said, fpr overrun creates a different kind of problem and most likely isn't causing your sputtering at WOT problem but you should should get it fixed anyway.

 

[NeOzz1]

http://www.dsmtuners.com/forums/showthread.php?p=1679803#post1679803 Check the conditions of your wires as well.


Oh yea, how much pressure did the system hold and for how long?


You're definitely overrunning the fpr. Pull the vacuum line off and try adjusting it down to 37psi. If it won't let you, you have the B&M Command flo which is the wrong fpr for our cars. With that said, fpr overrun creates a different kind of problem and most likely isn't causing your sputtering at WOT problem but you should should get it fixed anyway.

The wires are brand new

I did not see how much it would hold and for how long but i could not here any leaks leaving the air on there.

 

[oldman]

I did not see how much it would hold and for how long but i could not here any leaks leaving the air on there.

Explain to me in detail what tools and how are you performing the leak test? This is important.

 

[NeOzz1]

I take the intake tube off, then put a coupling on with a cap and a valve stem stuck in it, then i put the air comrpessor on it and listen for leaks, dont know how much air i am putting in, should i just watch the boost gage to tell?

basicaly the vfaq boost leak test

 

[oldman]

I take the intake tube off, then put a coupling on with a cap and a valve stem stuck in it, then i put the air comrpessor on it and listen for leaks, dont know how much air i am putting in, should i just watch the boost gage to tell?

Yes, there really isn't any other way, I have an extra gauge that I use to tap into the engine bay with so it becomes a one man job. the goal is 20psi holding for at least 30 seconds, a spray bottle of soapy water is a must.

 

[NeOzz1]

yea i got the soapy water down but I dont think I got up to 20 psi

so it should drop from 20 to 0 in 30 seconds or stay at 20 for 30 seconds?

BTW thanks for all of the help

 

[oldman]

so it should drop from 20 to 0 in 30 seconds

Yes, however, obviously the longer it will hold the better.

 

[NeOzz1]

how long should it hold 20 psi for me to know its not a boost leak that is making me stutter?

 

[oldman]

how long should it hold 20 psi for me to know its not a boost leak that is making me stutter?

In most cases, it will start to drop off immediately.

 

[NeOzz1]

so at 20 psi i should be able to heer it?

 

[oldman]

Trust me, if you can still hear hissing, you're no where near 20psi.

 

[NeOzz1]

ok i will try to find it asap, prob wed


i will post again once i see if it leaks


if it dont leak what should i try next or are u confident its going to?

 

[oldman]

This is only one of your problems, you still have issues like fuel pressure and such to deal with. I'm simply trying to help you to tie up loose ends that should have been dealt with anyway. If problem still persists then, the real cause will become more apparent.